A-Z Zoology Terms With Definitions – Zoology Glossary

Zoology Terms Starting With A

• Aestivation: A state of dormancy or torpor that some animals enter during hot or dry periods to avoid desiccation and extreme heat.
• Altricial: Refers to animals that are born in an underdeveloped state and require significant parental care, such as birds that hatch blind and featherless.
• Aposematism: The use of bright coloration or other warning signals by animals to indicate that they are toxic or unpalatable to predators.
• Antenna: A pair of long, thin sensory appendages on the heads of insects, crustaceans, and some other arthropods, used for detecting environmental cues.
• Amniotic Egg: An egg that contains a protective amnion, allowing reptiles, birds, and mammals to reproduce away from water.
• Amphibian: A class of cold-blooded vertebrates that typically have an aquatic larval stage and a terrestrial adult stage, such as frogs, salamanders, and newts.
• Annelid: A phylum of invertebrates that includes segmented worms like earthworms and leeches.
• Arthropod: A large phylum of invertebrates that includes insects, arachnids, and crustaceans, characterized by an exoskeleton, segmented body, and jointed appendages.
• Avian: Pertaining to birds; used to describe characteristics and behaviors specific to birds.
• Asexual Reproduction: A type of reproduction in which an organism produces offspring without the involvement of a mate, resulting in genetically identical offspring.
• Amphipod: A type of small crustacean with a laterally compressed body, commonly found in marine and freshwater environments.
• Abyssal Zone: The deep ocean zone, typically below 2,000 meters, where light does not penetrate and conditions are extreme.
• Abiotic: Refers to the non-living components of an ecosystem, such as temperature, water, and soil, that influence living organisms.
• Apical: Refers to the tip or apex of an organism or structure, often used in describing the growth regions of plants or the ends of animal appendages.
• Autotomy: The ability of certain animals to deliberately shed or amputate a body part, such as a tail, to escape from predators.
• Axial Skeleton: The part of the skeleton that includes the skull, vertebral column, and rib cage, supporting the central axis of the body.
• Aorta: The main artery that carries oxygenated blood from the heart to the rest of the body in vertebrates.
• Amphibious: Capable of living both on land and in water, often used to describe animals like frogs, turtles, and certain mammals.
• Aquatic: Relating to water; used to describe organisms that live in or around water, such as fish, amphibians, and aquatic plants.
• Adaptation: A characteristic or trait that has evolved in an organism to enhance its survival and reproduction in a specific environment.

Zoology Terms Starting With B

• Bilateral Symmetry: Symmetry in which the body can be divided into two equal halves along a single plane.
• Biodiversity: The variety of life in the world or in a particular habitat or ecosystem.
• Bioluminescence: The production and emission of light by a living organism.
• Bipedal: Using two legs for walking.
• Bivalve: A class of marine and freshwater mollusks with bodies enclosed by a shell consisting of two hinged parts.
• Blastula: An early stage of embryonic development that consists of a hollow ball of cells.
• Brood Parasitism: A reproductive strategy in which one species lays its eggs in the nest of another species.
• Bryophyte: A group of non-vascular plants that includes mosses, liverworts, and hornworts.
• Buccal Cavity: The mouth cavity.
• Budding: A form of asexual reproduction in which a new organism develops from an outgrowth or bud on the parent.
• Bursa: A fluid-filled sac that reduces friction between tissues of the body.
• Baleen: A filter-feeding system inside the mouths of baleen whales.
• Barbel: A slender, whisker-like sensory organ near the mouth of certain fish.
• Basal Metabolic Rate: The rate at which an organism uses energy while at rest to maintain vital functions.
• Batesian Mimicry: A form of mimicry in which a harmless species imitates the warning signals of a harmful species.
• Benthic: Relating to the bottom of a sea or lake or to the organisms that live there.
• Biotic: Relating to or resulting from living organisms.
• Boreal: Relating to the northern region or the northern forest biome.
• Brachiation: A form of locomotion used by some primates, involving swinging from branch to branch.
• Brackish Water: Water that has more salinity than freshwater but less than seawater.
• Brood: The young of certain animals, especially birds, produced at one hatching or birth.
• Bryozoan: A phylum of aquatic invertebrate animals that form colonies.
• Bursa of Fabricius: An organ in birds that is involved in the development of the immune system.
• Byssus: A bundle of filaments secreted by certain mollusks for attachment to a surface.
• Baleen Plate: A structure in the mouths of baleen whales used to filter food from water.
• Benthic Zone: The ecological region at the lowest level of a body of water.
• Biomass: The total mass of organisms in a given area or volume.
• Biotic Factor: A living component that affects the population of another organism or the environment.
• Boreal Forest: A forest biome characterized by coniferous trees and cold climates.
• Brachiopod: A phylum of marine invertebrates with bivalve dorsal and ventral shells.

Zoology Terms Starting With C

• Carnivore: An animal that feeds on other animals.
• Cephalopod: A class of mollusks that includes squid, octopuses, and cuttlefish.
• Chitin: A long-chain polymer found in the exoskeletons of arthropods and the cell walls of fungi.
• Chordate: Animals that possess a notochord at some stage in their development.
• Cilia: Hair-like structures that extend from the surface of many animal cells.
• Cnidocyte: A specialized cell in cnidarians that contains a stinging organelle.
• Coelom: A body cavity within animals that is lined with mesoderm.
• Commensalism: A relationship between two organisms where one benefits and the other is neither harmed nor helped.
• Coniferous: Trees that produce cones and have needle-like leaves.
• Crustacean: A large class of arthropods that includes crabs, lobsters, and shrimp.
• Cytoplasm: The material within a living cell, excluding the nucleus.
• Cocoon: A silky case spun by the larvae of many insects for protection during the pupal stage.
• Coccyx: The small, triangular bone at the base of the spinal column in humans and some other vertebrates.
• Coccygeal: Pertaining to the coccyx.

Zoology Terms Starting With D

• Dorsal: Referring to the upper side or back of an animal, often opposite to the ventral (belly) side.
• Detritivore: An organism that feeds on dead organic material, particularly plant detritus.
• Diphtheria: A bacterial infection affecting the mucous membranes, often spread between humans and animals.
• Dentition: The arrangement, type, and number of teeth in a particular species or individual.
• Diurnal: Describes animals that are active during the day and rest at night, opposite to nocturnal.
• DNA (Deoxyribonucleic Acid): The molecule that carries genetic instructions used in the growth, development, functioning, and reproduction of all living organisms.
• Digestive System: The system of organs responsible for breaking down food into nutrients that can be absorbed by the body.
• Deuterostome: A group of animals, including vertebrates, where the anus forms before the mouth during embryonic development.
• Diphyodont: An organism that has two successive sets of teeth, such as humans (milk teeth and permanent teeth).
• Dominance: A behavioral condition in which one individual in a social group asserts control or influence over others.
• Dimorphism: The occurrence of two different forms among the individuals of a species, usually referring to sexual dimorphism (differences between males and females).
• Dugong: A large marine mammal, closely related to the manatee, known for grazing on underwater grasses.
• Dodo: An extinct flightless bird that was endemic to the island of Mauritius.
• Diploid: A cell or organism having two sets of chromosomes, one from each parent.
• Diploblastic: Refers to animals that develop from two germ layers (ectoderm and endoderm) during embryonic development, such as jellyfish.
• Detoxification: The process by which an organism removes or neutralizes toxins.
• Dendrite: The branched projections of a neuron that receive signals from other neurons.
• Decapod: A group of crustaceans, such as crabs, lobsters, and shrimp, characterized by having ten limbs.
• Deforestation: The removal of large areas of forest, leading to habitat loss and changes in ecosystem dynamics.
• Decomposer: An organism, typically bacteria or fungi, that breaks down dead or decaying organic material, recycling nutrients back into the ecosystem.

Zoology Terms Starting With E

• Ecdysis: The process of shedding or molting the outer layer of skin, as seen in reptiles, insects, and other arthropods.
• Echinoderm: A phylum of marine animals characterized by radial symmetry and a calcareous skeleton, including starfish and sea urchins.
• Ectotherm: An organism that relies on external sources of heat to regulate its body temperature, commonly referred to as a cold-blooded animal.
• Ecosystem: A community of living organisms interacting with their physical environment, functioning as a unit.
• Ecotype: A genetically distinct population within a species that is adapted to specific environmental conditions.
• Ectoparasite: A parasite that lives on the surface of its host, such as fleas or lice.
• Efferent: Refers to nerves that carry impulses away from the central nervous system to effectors like muscles or glands.
• Elasmobranch: A subclass of cartilaginous fish that includes sharks, rays, and skates.
• Embryogenesis: The process by which an embryo forms and develops from a fertilized egg.
• Endangered Species: A species at risk of extinction due to a significant decline in its population or habitat.
• Endemic: Refers to a species that is native to a specific geographic area and found nowhere else.
• Endoparasite: A parasite that lives inside the body of its host, such as tapeworms.
• Endoskeleton: An internal skeleton made of bone or cartilage that provides support and protection to an organism.
• Endosymbiosis: A symbiotic relationship in which one organism lives inside the body or cells of another organism.
• Eocene: A geological epoch that occurred from about 56 to 34 million years ago, characterized by the emergence of modern mammals.
• Epidermis: The outermost layer of cells covering an organism, particularly in animals and plants.
• Epiphyte: A plant that grows on another plant for physical support but is not parasitic, often found in tropical rainforests.
• Epithelium: A type of tissue that lines the surfaces and cavities of organs and structures throughout the body.
• Erythrocyte: A red blood cell that carries oxygen from the lungs to the rest of the body.
• Eutherian: A group of mammals characterized by having a placenta, which allows for a longer gestation period.
• Exoskeleton: A rigid external covering that provides both support and protection to an organism, as seen in arthropods.
• Extant: A term used to describe species that are still living and not extinct.
• Extinct: A term used to describe species that no longer exist.
• Extracellular Matrix: A complex network of proteins and other molecules that provides structural and biochemical support to surrounding cells.
• Exudate: A fluid that leaks out of blood vessels into nearby tissues, usually as a result of inflammation.
• Eusociality: The highest level of social organization in animals, where individuals of the same species cooperate in caring for the young, have a division of labor, and have overlapping generations.
• Ecomorph: A form or structure of an organism that is adapted to a specific environmental niche.
• Endotherm: An organism that generates its own heat to maintain its body temperature, commonly referred to as a warm-blooded animal.
• Ectoderm: The outermost layer of cells or tissue in an embryo, which develops into the skin and nervous system.
• Epidemiology: The study of the distribution and determinants of health-related states or events in populations, and the application of this study to control health problems.
• Echolocation: The use of sound waves and echoes to determine the location of objects, used by animals such as bats and dolphins.
• Electrophoresis: A technique used to separate molecules, such as DNA or proteins, based on their size and charge by applying an electric field.
• Ecophysiology: The study of the physiological responses of organisms to their environment.
• Erythropoiesis: The process of producing red blood cells in the bone marrow.
• Eutrophication: The process by which a body of water becomes overly enriched with nutrients, leading to excessive growth of algae and depletion of oxygen.
• Epizootic: A disease that occurs at a higher-than-normal rate within an animal population.
• Endocrine Glands: Glands that secrete hormones directly into the bloodstream, such as the thyroid and adrenal glands.
• Excretion: The process by which waste products of metabolism and other non-useful materials are eliminated from an organism.
• Ecdysteroid: A group of hormones that play a role in molting and metamorphosis in arthropods.
• Exuviae: The remains of an exoskeleton left behind after ecdysis or molting.

Zoology Terms Starting With F

• Fertilization: The process by which male and female gametes unite to form a zygote, initiating the development of a new organism.
• Filoplume: A type of feather found in birds, typically associated with sensory functions and located near the base of other feathers.
• Fossorial: Refers to animals that are adapted to digging and living underground, such as moles.
• Frugivore: An animal that primarily eats fruit.
• Fungi: A kingdom of organisms that includes yeasts, molds, and mushrooms, which decompose organic matter and recycle nutrients in ecosystems.
• Fasciola: A genus of parasitic flatworms, also known as liver flukes, that infect the livers of various mammals, including humans.
• Fauna: The collective animal life of a particular region, habitat, or geological period.
• Flagellum: A whip-like structure that enables certain cells, such as sperm or some single-celled organisms, to move.
• Fibrinogen: A soluble plasma protein that is converted into fibrin during blood clotting.
• Filter Feeder: An aquatic animal that feeds by filtering small particles or organisms from the water, such as whales or clams.
• Follicle: A small secretory cavity, sac, or gland, such as a hair follicle or ovarian follicle.
• Foregut Fermentation: A digestive process seen in some herbivores where fermentation of plant material occurs in a specialized stomach chamber before reaching the small intestine.
• Formicidae: The scientific family name for ants, a diverse and widespread group of social insects.
• Foramen: A natural opening or hole in a bone that allows the passage of nerves or blood vessels.
• Fovea: A small pit or depression in the retina of the eye, where visual acuity is highest.
• Fusiform: Spindle-shaped; tapering at both ends, commonly used to describe the body shape of certain fish and other animals.
• Fecundity: The potential reproductive capacity of an individual or population, often measured by the number of eggs produced.
• Forelimb: The front limb of an animal, equivalent to an arm or wing.
• Flagellate: A type of protozoan that moves using one or more flagella.
• Flight Feathers: The strong feathers on the wings and tail of birds that are essential for flight.
• Furcula: Also known as the “wishbone,” it is a forked bone found in birds, formed by the fusion of two clavicles.
• Facultative Parasite: An organism that can live both as a parasite and independently of a host.
• Free-Living: Refers to organisms that do not rely on a host for survival, as opposed to parasitic organisms.
• Fibrillation: Rapid, irregular, and unsynchronized contraction of muscle fibers, particularly in the heart.
• Flatworm: A group of simple, soft-bodied invertebrates belonging to the phylum Platyhelminthes, many of which are parasitic.
• Frontal Bone: The bone forming the front part of the skull and the upper part of the eye sockets.
• Fusiform Muscle: A type of muscle that is spindle-shaped with a central belly that tapers toward both ends, found in certain limbs.
• Fibrin: An insoluble protein formed from fibrinogen during the clotting of blood; it forms a fibrous mesh that impedes blood flow.
• Fluke: A parasitic flatworm of the class Trematoda, typically found in the liver or lungs of vertebrates.
• Fibrillation: Rapid, irregular contractions of muscle fibers, especially in the heart.
• Fascia: A band or sheet of connective tissue that supports and surrounds muscles and other organs.
• Femur: The thigh bone, the longest and strongest bone in the body, found in the hind limbs of vertebrates.
• Flagellated Cell: A cell equipped with one or more flagella for movement or sensory functions.
• Folivorous: Refers to animals that primarily consume leaves.
• Fat Body: A tissue in insects and some other arthropods that stores nutrients and functions similarly to the liver in vertebrates.
• Fovea Centralis: A small, central pit in the retina responsible for sharp central vision.
• Fibrinogen: A plasma protein that is essential for blood clotting, converting into fibrin in response to injury.
• Foetus: The developing offspring within the uterus of a mammal after the embryonic stage and before birth.
• Foraging: The behavior of searching for and exploiting food resources.
• Fossil: The preserved remains or traces of organisms from the past, typically found in sedimentary rocks.

Zoology Terms Starting With G

• Gametogenesis: The process by which gametes (sex cells) are produced in an organism.
• Ganglion: A structure containing a number of nerve cell bodies, typically linked by synapses.
• Gastrovascular Cavity: A central cavity in some invertebrates that functions in both digestion and circulation.
• Genotype: The genetic constitution of an individual organism.
• Germ Layer: One of the three primary layers of cells (ectoderm, mesoderm, endoderm) in the embryo.
• Gestation: The period of development from the fertilization of the egg to the birth of the offspring.
• Gill: A respiratory organ found in many aquatic organisms that extracts oxygen from water.
• Gizzard: A muscular, thick-walled part of a bird’s stomach for grinding food, typically with grit.
• Glycogen: A form of stored glucose; primarily found in the liver and muscles.
• Gnathostome: Jawed vertebrates.
• Gonad: An organ that produces gametes; a testis or ovary.
• Gonopore: An opening through which gametes are released.
• Granivore: An animal that primarily eats seeds.
• Gravid: Carrying eggs or young; pregnant.
• Gregarious: Living in flocks or loosely organized communities.
• Guard Hair: The long, coarse hair that forms the outer layer of an animal’s coat.
• Gular: Pertaining to the throat.
• Gymnosperm: A group of seed-producing plants that includes conifers.
• Gynandromorph: An organism that contains both male and female characteristics.
• Gynogenesis: A form of asexual reproduction that requires the presence of sperm but not its genetic contribution.
• Gyrencephalic: Having a brain with convolutions or folds.
• Gizzard: A muscular, thick-walled part of a bird’s stomach for grinding food, typically with grit.
• Glycogen: A form of stored glucose; primarily found in the liver and muscles.
• Gnathostome: Jawed vertebrates.
• Gonad: An organ that produces gametes; a testis or ovary.
• Gonopore: An opening through which gametes are released.
• Granivore: An animal that primarily eats seeds.
• Gravid: Carrying eggs or young; pregnant.
• Gregarious: Living in flocks or loosely organized communities.
• Guard Hair: The long, coarse hair that forms the outer layer of an animal’s coat.
• Gular: Pertaining to the throat.
• Gymnosperm: A group of seed-producing plants that includes conifers.
• Gynandromorph: An organism that contains both male and female characteristics.
• Gynogenesis: A form of asexual reproduction that requires the presence of sperm but not its genetic contribution.
• Gyrencephalic: Having a brain with convolutions or folds.
• Gizzard: A muscular, thick-walled part of a bird’s stomach for grinding food, typically with grit.
• Glycogen: A form of stored glucose; primarily found in the liver and muscles.
• Gnathostome: Jawed vertebrates.
• Gonad: An organ that produces gametes; a testis or ovary.
• Gonopore: An opening through which gametes are released.

Zoology Terms Starting With H

• Habitat: The natural home or environment of an animal, plant, or other organism.
• Hemoglobin: A protein in red blood cells that carries oxygen.
• Herbivore: An animal that feeds on plants.
• Hermaphrodite: An organism that has both male and female reproductive organs.
• Hibernation: A state of inactivity and metabolic depression in endotherms.
• Hindgut: The posterior part of the digestive system.
• Homeostasis: The ability to maintain a stable internal environment.
• Homologous Structures: Anatomical features that are similar in different species because of common ancestry.
• Hominid: A member of the biological family Hominidae, which includes humans, chimpanzees, gorillas, and orangutans.
• Hormone: A regulatory substance produced in an organism to stimulate specific cells or tissues into action.
• Hybrid: The offspring of two plants or animals of different species or varieties.
• Hydrostatic Skeleton: A structure found in many ectothermic organisms and soft-bodied animals consisting of a fluid-filled cavity, the coelom, surrounded by muscles.
• Hyperplasia: An increase in the number of cells in an organ or tissue.
• Hypothalamus: A region of the brain that controls body temperature, hunger, and other homeostatic systems.
• Hemocoel: The primary body cavity of most invertebrates, containing circulatory fluid.
• Heterotroph: An organism that cannot synthesize its own food and is dependent on complex organic substances for nutrition.
• Heterozygous: Having two different alleles of a particular gene or genes.
• Holometabolous: Undergoing complete metamorphosis, with distinct larval, pupal, and adult stages.
• Homoeothermic: Maintaining a constant body temperature regardless of environmental temperature.
• Humerus: The bone of the upper arm or forelimb.
• Hydrophilic: Having an affinity for water.
• Hydrophobic: Repelling water.
• Hymenoptera: An order of insects that includes bees, wasps, and ants.
• Hypoxia: A deficiency in the amount of oxygen reaching the tissues.
• Hemiptera: An order of insects also known as true bugs, including aphids and cicadas.
• Hepatic: Relating to the liver.
• Heterocercal: Having unequal upper and lower lobes, typically referring to the tail fin of some fish.
• Heterodont: Having teeth of different types.
• Heterotrophic: Obtaining food by consuming other organisms.
• Holoblastic: Referring to a type of cleavage in which the entire egg is divided into smaller cells.
• Holotype: The single specimen upon which the description and name of a new species is based.
• Humerus: The bone of the upper arm or forelimb.
• Hydrophilic: Having an affinity for water.
• Hydrophobic: Repelling water.
• Hymenoptera: An order of insects that includes bees, wasps, and ants.
• Hypoxia: A deficiency in the amount of oxygen reaching the tissues.
• Hemiptera: An order of insects also known as true bugs, including aphids and cicadas.
• Hepatic: Relating to the liver.
• Heterocercal: Having unequal upper and lower lobes, typically referring to the tail fin of some fish.
• Heterodont: Having teeth of different types.

Zoology Terms Starting With I

• Ichthyology: The branch of zoology that deals with fishes.
• Imago: The final and fully developed adult stage of an insect.
• Immune System: The body’s defense system against infections and diseases.
• Insectivore: An animal that primarily feeds on insects.
• Instar: A developmental stage of arthropods, such as insects, between each molt until sexual maturity is reached.
• Integument: The natural outer covering of an organism, such as skin or a shell.
• Intertidal Zone: The area between the high tide and low tide marks.
• Invertebrate: An animal lacking a backbone.
• Iridophore: A type of chromatophore that reflects light, producing iridescent colors.
• Isopod: A type of crustacean with a flattened body and seven pairs of legs.
• Ichthyosaur: An extinct marine reptile that resembled a fish.
• Immunology: The study of the immune system.
• Incisor: A type of tooth adapted for cutting.
• Indeterminate Growth: Growth that is not terminated; the organism continues to grow throughout its life.
• Inflorescence: The arrangement of flowers on a plant.
• Ingestive: Pertaining to the intake of food.
• Insect: A class of arthropods with a three-part body, three pairs of legs, and usually two pairs of wings.
• Insulin: A hormone that regulates blood sugar levels.
• Integumentary System: The organ system that includes skin, hair, nails, and associated glands.
• Intracellular: Located or occurring within a cell.
• Intraspecific: Occurring within a species.
• Invasive Species: A non-native species that spreads widely in a new habitat.
• Iridescence: The phenomenon of certain surfaces that appear to change color as the angle of view or the angle of illumination changes.
• Isogamy: A form of sexual reproduction involving gametes of similar morphology.
• Isotope: Variants of a particular chemical element that differ in neutron number.
• Isotonic: Having the same osmotic pressure as another fluid.
• Ivermectin: A medication used to treat many types of parasite infestations.
• Ichthyofauna: The fish population of a particular region.
• Immunocompromised: Having an impaired or weakened immune system.
• Incubation: The process of keeping eggs warm until they hatch.
• Indigenous: Native to a particular region or environment.
• Inoculation: The introduction of a pathogen or antigen into a living organism to stimulate the production of antibodies.
• Insecticide: A substance used for killing insects.
• Interbreeding: Breeding between individuals of different populations or species.
• Intercellular: Located or occurring between cells.
• Interneuron: A neuron that transmits impulses between other neurons.
• Intraspecific Competition: Competition among members of the same species.
• Invertebrate Zoology: The study of animals without backbones.
• Irritability: The ability of an organism to respond to stimuli.
• Isoptera: An order of insects that includes termites.

Zoology Terms Starting With J

• Jacobson’s Organ: A chemoreceptor organ found in many animals, used for detecting pheromones.
• Jellyfish: A free-swimming marine coelenterate with a gelatinous umbrella-shaped bell and trailing tentacles.
• Jugular: Pertaining to the throat or neck.
• Juvenile: The stage of an organism’s life cycle between the larval stage and adulthood.
• Jugal Bone: A bone in the skull of vertebrates, also known as the cheekbone.
• Jugal Arch: The bony arch of the cheek.
• Jugal Point: The point where the jugal bone meets the maxilla.
• Jugal Process: A projection of the jugal bone.
• Jugal Suture: The joint between the jugal bone and the maxilla.
• Jugal Symphysis: The junction where the two halves of the jugal bone meet.
• Jugal Tubercle: A small rounded projection on the jugal bone.
• Jugal Ridge: A raised line on the jugal bone.
• Jugal Crest: A prominent ridge on the jugal bone.
• Jugal Notch: A notch in the jugal bone.
• Jugal Foramen: An opening in the jugal bone.
• Jugal Fossa: A depression in the jugal bone.
• Jugal Groove: A groove in the jugal bone.
• Jugal Canal: A canal in the jugal bone.
• Jugal Sinus: A cavity in the jugal bone.
• Jugal Cavity: A hollow space in the jugal bone.
• Jugal Plate: A flat part of the jugal bone.
• Jugal Lamina: A thin layer of the jugal bone.
• Jugal Septum: A partition in the jugal bone.
• Jugal Spine: A spine-like projection on the jugal bone.
• Jugal Tuberosity: A roughened area on the jugal bone.
• Jugal Process of the Maxilla: A projection of the maxilla that articulates with the jugal bone.
• Jugal Process of the Temporal Bone: A projection of the temporal bone that articulates with the jugal bone.
• Jugal Process of the Zygomatic Bone: A projection of the zygomatic bone that articulates with the jugal bone.
• Jugal Process of the Frontal Bone: A projection of the frontal bone that articulates with the jugal bone.
• Jugal Process of the Parietal Bone: A projection of the parietal bone that articulates with the jugal bone.
• Jugal Process of the Nasal Bone: A projection of the nasal bone that articulates with the jugal bone.
• Jugal Process of the Lacrimal Bone: A projection of the lacrimal bone that articulates with the jugal bone.
• Jugal Process of the Palatine Bone: A projection of the palatine bone that articulates with the jugal bone.
• Jugal Process of the Vomer: A projection of the vomer that articulates with the jugal bone.
• Jugal Process of the Sphenoid Bone: A projection of the sphenoid bone that articulates with the jugal bone.
• Jugal Process of the Ethmoid Bone: A projection of the ethmoid bone that articulates with the jugal bone.
• Jugal Process of the Inferior Nasal Concha: A projection of the inferior nasal concha that articulates with the jugal bone.

Zoology Terms Starting With K

• Karyotype: The number and appearance of chromosomes in the nucleus of a eukaryotic cell, used to study genetic disorders.
• Keratin: A fibrous protein that forms the main structural component of hair, feathers, claws, and the outer layer of skin.
• Keystone Species: A species that plays a crucial role in maintaining the structure of an ecological community, affecting many other organisms in the ecosystem.
• Kinesis: A non-directional movement response of an organism to a stimulus, where the speed of movement is related to the intensity of the stimulus.
• Kin Selection: An evolutionary strategy that favors the reproductive success of an organism’s relatives, even at a cost to the organism’s own survival and reproduction.
• Kidney: An organ in vertebrates that filters blood to remove waste products and produce urine.
• Kleptoparasitism: A form of feeding where one animal takes food that another has caught or collected.
• Krill: Small, shrimp-like marine crustaceans that are a key food source for many larger marine animals, such as whales.
• Karyogamy: The fusion of two nuclei within a cell, typically occurring during fertilization.
• Keratinocyte: A type of cell that makes up the majority of the epidermis, responsible for producing keratin.
• Karyolysis: The dissolution or disintegration of a cell nucleus, often as a result of cell death.
• Kinesis: A random movement of an organism in response to a stimulus, where the rate of movement changes with stimulus intensity.
• Knot: A large flock of birds, especially shorebirds, that gather in a tight group.
• Kelp: Large brown seaweeds (algae) that form underwater forests and provide habitat for many marine organisms.
• Kin Recognition: The ability of an organism to distinguish between its relatives and non-relatives, often to avoid inbreeding.
• Killer Whale: A large predatory marine mammal, also known as orca, that is part of the dolphin family.
• Karyorrhexis: The fragmentation of a cell’s nucleus during cell death.
• Keratinization: The process by which cells produce keratin and become part of the outermost layer of skin, hair, or nails.
• Karyoplasm: The substance within the nucleus of a cell, also known as nucleoplasm.
• Kangaroo Rat: A small, nocturnal rodent adapted to desert environments, known for its ability to survive without drinking water.
• Krebs Cycle: A series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetyl-CoA.
• Karyomere: A small, membrane-bound structure containing a nucleus or part of a nucleus.
• Koinobiont: A type of parasitoid that allows its host to continue growing after being parasitized, eventually killing it.
• Karyotype Analysis: A laboratory technique used to visualize and analyze the number and structure of chromosomes in a cell.
• K-strategist: An organism that produces fewer offspring, with a high investment in parental care, and typically has a longer lifespan.
• Keratinous: Composed of or resembling keratin, such as the scales of reptiles or the beaks of birds.
• Kinetic: Relating to or resulting from motion, often used to describe the movement of organisms in response to stimuli.
• Kakapo: A large, flightless parrot native to New Zealand, known for its nocturnal habits and critically endangered status.
• Kleptothermy: A behavior where an organism conserves energy by sharing body heat with others, such as reptiles basking together.
• Karyogram: A diagram or photograph of an individual’s chromosomes arranged in homologous pairs.

Zoology Terms Starting With L

• Larva: The immature, juvenile form of an animal that undergoes metamorphosis, typically found in insects, amphibians, and some other groups.
• Lichen: A symbiotic association between a fungus and an alga or cyanobacterium, often found on rocks and trees.
• Lipid: A group of naturally occurring molecules that include fats, oils, and hormones, essential for storing energy and forming cell membranes.
• Litter: The offspring born at one time to a mammal, especially in species that have multiple births.
• Lymph: A clear fluid that circulates through the lymphatic system, carrying cells that help fight infection.
• Leukocyte: A white blood cell involved in the body’s immune response, defending against infections and foreign substances.
• Lepidoptera: The order of insects that includes butterflies and moths, characterized by their scaled wings.
• Lateral Line: A sensory organ in fish and some amphibians that detects vibrations and movements in the water.
• Lithosphere: The rigid outer layer of the Earth, including the crust and upper mantle, where many organisms live.
• Locomotion: The movement or ability to move from one place to another, essential for finding food, mates, and escaping predators.
• Lysozyme: An enzyme that breaks down bacterial cell walls, found in many animal tissues and secretions, such as saliva and tears.
• Lactation: The production and secretion of milk by female mammals to nourish their young.
• Lignin: A complex organic polymer found in the cell walls of plants, providing structural support and protection.
• Locus: The specific location of a gene or DNA sequence on a chromosome.
• Lumbricus: A genus of earthworms, commonly found in soils, that play a key role in decomposing organic matter.
• Leptocephalus: The transparent, leaf-shaped larval form of eels and some other fish.
• Lophophore: A crown of ciliated tentacles found in certain invertebrate animals, used for feeding and respiration.
• Lynx: A medium-sized wild cat known for its tufted ears, short tail, and solitary behavior, found in the northern hemisphere.
• Limnetic Zone: The well-lit, open surface waters of a lake, away from the shore, where photosynthesis occurs.
• Lateralization: The specialization of certain functions, such as speech or handedness, in one hemisphere of the brain.
• Leptin: A hormone produced by fat cells that regulates energy balance by inhibiting hunger.
• Lithophore: An organism that lives on or within rocks, often seen in harsh environments such as deserts.
• Lophodont: Refers to molar teeth with ridged surfaces, adapted for grinding plant material, found in some herbivores.
• Lysosome: A membrane-bound organelle in cells that contains enzymes for breaking down waste materials and cellular debris.
• Lancelet: A small, elongated marine animal that is a member of the subphylum Cephalochordata, closely related to vertebrates.
• Lotic: Pertaining to or living in flowing water, such as rivers and streams, as opposed to still water.
• Labyrinth: A complex structure in the inner ear of vertebrates, involved in maintaining balance and hearing.
• Lecithotrophic: Refers to embryos or larvae that are nourished by yolk rather than by a direct connection to the mother.
• Leucism: A genetic condition resulting in reduced pigmentation, causing animals to appear pale or white, but not affecting the eyes.
• Luminescence: The emission of light by a substance or organism, often seen in bioluminescent animals like fireflies and deep-sea creatures.

Zoology Terms Starting With M

• Macrophage: A type of white blood cell that engulfs and digests cellular debris, foreign substances, and pathogens.
• Mandible: The lower jawbone in vertebrates.
• Mammal: A class of warm-blooded vertebrates characterized by the presence of mammary glands, hair, and three middle ear bones.
• Marsupial: A subclass of mammals, most of which carry and nurse their young in a pouch.
• Metamorphosis: A biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal’s body structure.
• Mimicry: The resemblance of one organism to another or to an object in its surroundings for concealment and protection from predators.
• Mitochondrion: An organelle found in large numbers in most cells, where the biochemical processes of respiration and energy production occur.
• Mollusk: A large phylum of invertebrate animals that includes snails, slugs, mussels, and octopuses.
• Monotreme: A primitive order of egg-laying mammals, including the platypus and echidna.
• Morphology: The study of the form and structure of organisms and their specific structural features.
• Mycology: The branch of biology concerned with the study of fungi.
• Myelin: A fatty substance that surrounds the axon of some nerve cells, forming an electrically insulating layer.
• Myofibril: A basic rod-like unit of a muscle cell.
• Myriapod: A group of arthropods that includes centipedes and millipedes.
• Myxomatosis: A disease caused by the Myxoma virus, affecting rabbits.
• Macula: An oval-shaped pigmented area near the center of the retina in the human eye.
• Malpighian Tubule: A type of excretory and osmoregulatory system found in some insects.
• Mandibulate: Having mandibles or jaw-like structures.
• Mantle: A significant part of the anatomy of mollusks, which secretes the shell.
• Maxilla: The upper jawbone in vertebrates.
• Melanin: A pigment that gives the skin, hair, and eyes their color.
• Mesoderm: The middle layer of an embryo in early development.
• Metabolism: The set of life-sustaining chemical reactions in organisms.
• Microbiome: The collection of all the microorganisms living in association with the human body.
• Microscope: An instrument used to see objects that are too small to be seen by the naked eye.
• Mimic: An organism that resembles another organism or object.
• Mitochondrial DNA: The DNA located in mitochondria, inherited only through the mother.
• Molt: The process of shedding an old exoskeleton or skin to allow for growth.
• Monogamy: A mating system in which one male mates with one female exclusively.
• Mutualism: A type of symbiotic relationship where both species benefit.

Zoology Terms Starting With N

• Nacre: Also known as mother-of-pearl, it is the iridescent substance forming the inner layer of the shell of some mollusks.
• Nematode: A phylum of worms also known as roundworms.
• Nephridium: An excretory organ in many invertebrates.
• Neurotransmitter: Chemicals that transmit signals across a synapse from one neuron to another.
• Niche: The role or function of an organism or species within an ecosystem.
• Nidification: The process of building a nest.
• Notochord: A flexible rod made out of a material similar to cartilage. If a species has a notochord, it is, by definition, a chordate.
• Nucleus: The membrane-bound structure in a cell that contains the genetic material.
• Nymph: An immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage.
• Nocturnal: Active during the night.
• Neoteny: The retention of juvenile features in the adult animal.
• Neurogenesis: The process by which new neurons are formed in the brain.
• Neurotoxin: A toxin that acts on the nervous system.
• Nictitating Membrane: A transparent or translucent third eyelid present in some animals.
• Nidicolous: Referring to animals that stay in the nest for a long time after hatching.
• Nidifugous: Referring to animals that leave the nest shortly after hatching.
• Nematocyst: A specialized cell in the tentacles of a jellyfish or other coelenterate, containing a barbed or venomous coiled thread.
• Nephrons: The functional units of the kidney.
• Neuroglia: The supportive tissue of the nervous system.
• Nematocyst: A specialized cell in the tentacles of a jellyfish or other coelenterate, containing a barbed or venomous coiled thread.
• Neurolemma: The outermost nucleated cytoplasmic layer of Schwann cells that surrounds the axon of the neuron.
• Neuroplasticity: The ability of the brain to change continuously throughout an individual’s life.
• Nidicolous: Referring to animals that stay in the nest for a long time after hatching.
• Nidifugous: Referring to animals that leave the nest shortly after hatching.
• Nematocyst: A specialized cell in the tentacles of a jellyfish or other coelenterate, containing a barbed or venomous coiled thread.
• Nephrons: The functional units of the kidney.
• Neuroglia: The supportive tissue of the nervous system.
• Neurolemma: The outermost nucleated cytoplasmic layer of Schwann cells that surrounds the axon of the neuron.
• Neuroplasticity: The ability of the brain to change continuously throughout an individual’s life.
• Nidicolous: Referring to animals that stay in the nest for a long time after hatching.

Zoology Terms Starting With O

• Oogenesis: The process of egg cell (ovum) development in female animals.
• Osmoregulation: The process by which animals regulate the balance of water and salts in their bodies.
• Omnivore: An organism that eats both plant and animal matter.
• Oviparous: Referring to animals that lay eggs, with little or no other embryonic development within the mother.
• Ocelli: Simple eyes or eye-like spots found in some invertebrates, used to detect light and dark.
• Operculum: A bony plate that covers the gills of fish, protecting them and aiding in respiration.
• Ontogeny: The development of an individual organism from fertilization to maturity.
• Olfaction: The sense of smell, used by many animals to detect odors in their environment.
• Osteichthyes: A class of fish known as bony fish, characterized by a skeleton primarily composed of bone.
• Osteocyte: A mature bone cell that maintains bone tissue.
• Ornithology: The scientific study of birds.
• Ommatidia: The individual visual units that make up the compound eyes of arthropods.
• Osmosis: The movement of water molecules through a semi-permeable membrane from a region of lower solute concentration to higher concentration.
• Oestrus: The period of sexual receptivity and fertility in female mammals, often referred to as being “in heat.”
• Omohyoid: A muscle in the neck of vertebrates that plays a role in swallowing and speech.
• Oral Disc: The mouth region in certain invertebrates, such as cnidarians, often surrounded by tentacles.
• Osmoconformer: An organism that maintains its internal environment isosmotic to its external environment, common in many marine invertebrates.
• Opisthosoma: The posterior part of the body in arachnids and some other arthropods, commonly referred to as the abdomen.
• Olfactory Bulb: A neural structure involved in the sense of smell, located in the forebrain of vertebrates.
• Operant Conditioning: A learning process through which the strength of a behavior is modified by reinforcement or punishment.
• Oogenesis: The production of eggs or ova in female animals, typically occurring in the ovaries.
• Ocellus: A small, simple eye found in invertebrates, capable of detecting light intensity but not forming images.
• Osteology: The study of the structure and function of the skeleton and bones.
• Ovoviviparous: Referring to animals that produce eggs that develop and hatch within the mother’s body, with the young being born live.
• Orbital Cavity: The bony socket that contains the eye, also known as the eye socket.
• Oocyte: An immature egg cell that undergoes development during oogenesis.
• Osmotroph: An organism that absorbs dissolved organic compounds through osmosis, commonly seen in fungi and some protists.
• Ossification: The process by which bone is formed, renewed, and repaired in animals.
• Osteoblast: A type of cell responsible for bone formation.
• Osmotic Pressure: The pressure required to prevent the flow of water across a semi-permeable membrane due to osmosis.

Zoology Terms Starting With P

• Parasitism: A symbiotic relationship where one organism (the parasite) benefits at the expense of another (the host).
• Pheromone: A chemical substance produced and released by an animal, affecting the behavior or physiology of others of its species.
• Photosynthesis: The process by which plants, algae, and some bacteria convert light energy into chemical energy, producing oxygen as a byproduct.
• Plankton: Small and microscopic organisms drifting or floating in the sea or freshwater, forming the base of many aquatic food chains.
• Polymorphism: The occurrence of different forms, types, or morphs within a species, often seen in the coloration or structure of animals.
• Predation: The act of one organism (the predator) hunting and consuming another organism (the prey).
• Phylum: A major taxonomic group of animals or plants, ranking above class and below kingdom.
• Pinniped: A member of the group of marine mammals that includes seals, sea lions, and walruses, characterized by their flippers.
• Parthenogenesis: A form of asexual reproduction where an egg develops into an individual without fertilization.
• Pelage: The fur, hair, or wool covering the body of a mammal.
• Photoreceptor: A specialized cell or structure that responds to light, such as those found in the retina of the eye.
• Plastron: The ventral (bottom) part of a turtle or tortoise shell.
• Polygyny: A mating system in which a male has multiple female partners.
• Phylogeny: The evolutionary history and relationships among individuals or groups of organisms.
• Pinnate: Referring to a feather-like or compound structure with parts arranged on either side of a central axis, such as in the wings of birds.
• Polymorphonuclear: Referring to white blood cells with a multi-lobed nucleus, such as neutrophils.
• Pheromone: A chemical signal released by an animal that influences the behavior of other members of the same species.
• Porifera: The phylum of aquatic invertebrates known as sponges, characterized by their porous bodies.
• Plumage: The feathers covering a bird’s body, often used for flight, insulation, and display.
• Proboscis: An elongated, flexible appendage on the head of an animal, used for feeding or sensing, as seen in insects like butterflies and mosquitoes.
• Polyandry: A mating system in which a female has multiple male partners.
• Protostome: A major group of animals characterized by the mouth forming before the anus during embryonic development.
• Placenta: An organ that develops in the uterus during pregnancy in mammals, facilitating the exchange of nutrients and waste between mother and fetus.
• Pectoral Fin: One of the paired fins located on the sides of a fish, used for steering and stabilization during swimming.
• Photoperiodism: The physiological reaction of organisms to the length of day or night, affecting behaviors such as reproduction and migration.
• Phagocytosis: The process by which a cell engulfs and digests solid particles, such as bacteria or debris, seen in immune cells like macrophages.
• Plasmodium: A genus of parasitic protozoa that causes malaria in humans and other animals.
• Prehensile: Capable of grasping or holding objects, often referring to tails or limbs in animals like monkeys and opossums.
• Pupa: The life stage of some insects undergoing transformation between larva and adult, as seen in butterflies and beetles.
• Parapodia: Paired, lateral appendages found in some annelid worms, used for locomotion and sometimes respiration.

Zoology Terms Starting With Q

• Quadrate: A bone in the skull of most vertebrates that connects the jaw to the skull.
• Quadriceps: A large muscle group that includes the four prevailing muscles on the front of the thigh.
• Quadruped: An animal that walks on four legs.
• Quarantine: A period of isolation to prevent the spread of disease.
• Quaternary Structure: The structure formed by several protein molecules (polypeptide chains), usually called protein subunits.
• Quill: The hollow, sharp spines of a porcupine or the large feathers of a bird.
• Quorum Sensing: A system of stimuli and response correlated to population density.
• Quiescence: A state of inactivity or dormancy.
• Quillwort: A type of aquatic plant that resembles a quill.
• Quokka: A small marsupial found in Australia.
• Quoll: A carnivorous marsupial native to Australia and New Guinea.
• Qubit: A unit of quantum information.
• Quagga: An extinct subspecies of plains zebra.
• Quinone: A class of organic compounds that are derived from aromatic compounds.
• Quagga Mussel: An invasive species of freshwater mussel.
• Quillwort: A type of aquatic plant that resembles a quill.
• Quercetin: A plant pigment (flavonoid) found in many plants and foods.
• Quillback: A type of freshwater fish.
• Quercus: The genus of trees and shrubs commonly known as oaks.
• Quinone: A class of organic compounds that are derived from aromatic compounds.

Zoology Terms Starting With R

• Radial Symmetry: Symmetry around a central axis, as in a starfish or a tulip flower.
• Radiata: A taxonomic rank used to classify animals with radial symmetry.
• Radula: A tongue-like organ covered with teeth that mollusks use to scrape food into their mouths.
• Raptor: A bird of prey, such as an eagle or hawk.
• Receptor: A protein molecule that receives and responds to a neurotransmitter or hormone.
• Recombination: The process by which genetic material is broken and joined to other genetic material.
• Regeneration: The process of renewal, restoration, and growth.
• Reptile: A class of cold-blooded vertebrates that includes snakes, lizards, crocodiles, and turtles.
• Respiration: The process of inhaling oxygen and exhaling carbon dioxide.
• Retina: The light-sensitive layer of tissue at the back of the inner eye.
• Rhinoceros: A large, thick-skinned herbivorous mammal with one or two horns on its snout.
• Ribosome: A complex molecular machine found within all living cells that produces proteins.
• Rodent: A mammal of the order Rodentia, characterized by a single pair of continuously growing incisors in each of the upper and lower jaws.
• Roe: The eggs of fish and certain marine animals.
• Ruminant: A mammal that chews cud regurgitated from its rumen, such as a cow or sheep.
• Raptor: A bird of prey, such as an eagle or hawk.
• Receptor: A protein molecule that receives and responds to a neurotransmitter or hormone.
• Recombination: The process by which genetic material is broken and joined to other genetic material.
• Regeneration: The process of renewal, restoration, and growth.
• Reptile: A class of cold-blooded vertebrates that includes snakes, lizards, crocodiles, and turtles.
• Respiration: The process of inhaling oxygen and exhaling carbon dioxide.
• Retina: The light-sensitive layer of tissue at the back of the inner eye.
• Rhinoceros: A large, thick-skinned herbivorous mammal with one or two horns on its snout.
• Ribosome: A complex molecular machine found within all living cells that produces proteins.
• Rodent: A mammal of the order Rodentia, characterized by a single pair of continuously growing incisors in each of the upper and lower jaws.
• Roe: The eggs of fish and certain marine animals.
• Ruminant: A mammal that chews cud regurgitated from its rumen, such as a cow or sheep.
• Raptor: A bird of prey, such as an eagle or hawk.
• Receptor: A protein molecule that receives and responds to a neurotransmitter or hormone.
• Recombination: The process by which genetic material is broken and joined to other genetic material.

Zoology Terms Starting With S

• Species: The basic unit of biological classification, a group of organisms capable of interbreeding and producing fertile offspring.
• Symbiosis: Interaction between two different organisms living in close physical association, typically to the advantage of both.
• Spermatogenesis: The process by which sperm cells are produced and developed.
• Sessile: Describes an organism that is fixed in one place; immobile.
• Scavenger: An animal that feeds on dead or decaying organic matter.
• Sclerite: A hardened body part or plate, often found in arthropods.
• Siphon: A tube-like structure through which water enters and leaves the bodies of certain aquatic animals.
• Spermatophore: A capsule or mass created by males of various species, containing spermatozoa and transferred to the female’s reproductive tract.
• Subspecies: A taxonomic category that ranks below species, usually a fairly permanent geographically isolated race.
• Saprozoic: Feeding on decaying organic matter.
• Sclerotization: The process of hardening of the cuticle in arthropods.
• Spicule: A small, needle-like structure found in sponges and other invertebrates.
• Siphonophore: A colonial marine organism made up of specialized individual animals (zooids).
• Spermatheca: A sac in the female reproductive system of some invertebrates where sperm is stored after mating.
• Sclerophyll: A type of vegetation with hard leaves adapted to dry climates.
• Saprobes: Organisms that obtain food from decaying organic matter.
• Spermatocyte: A cell in the testes that undergoes meiosis to form spermatids.
• Siphuncle: A tube-like structure in cephalopods used to regulate buoyancy.
• Sclerite: A hardened body part or plate, often found in arthropods.
• Spermatid: An immature male sex cell formed from a spermatocyte that can develop into a spermatozoon.
• Saprozoic: Feeding on decaying organic matter.
• Sclerotome: The part of a somite in a vertebrate embryo that gives rise to bone or other skeletal tissue.
• Siphonoglyph: A ciliated groove in the pharynx of sea anemones and some corals.
• Spermatogenesis: The process by which sperm cells are produced and developed.
• Saprozoic: Feeding on decaying organic matter.
• Sclerotization: The process of hardening of the cuticle in arthropods.
• Spicule: A small, needle-like structure found in sponges and other invertebrates.
• Siphonophore: A colonial marine organism made up of specialized individual animals (zooids).
• Spermatheca: A sac in the female reproductive system of some invertebrates where sperm is stored after mating.
• Sclerophyll: A type of vegetation with hard leaves adapted to dry climates.

Zoology Terms Starting With T

• Taxonomy: The science of classification of organisms.
• Trophic Level: The position an organism occupies in a food chain.
• Tympanum: A membrane in the ear of some animals, such as frogs, that vibrates in response to sound waves.
• Torpor: A state of decreased physiological activity in an animal, usually by a reduced body temperature and metabolic rate.
• Tarsus: The part of the leg of an insect or other arthropod that is attached to the tibia.
• Tegument: The outer body covering of certain invertebrates, such as nematodes.
• Trophic Cascade: A series of changes in the population sizes of organisms at different trophic levels in a food chain, usually caused by the addition or removal of a key predator.
• Tympanic Membrane: Another term for the eardrum.
• Taxis: Movement of an organism in response to a stimulus such as light or the presence of food.
• Trachea: The windpipe; a tube that connects the pharynx and larynx to the lungs.
• Tendril: A slender, thread-like appendage of a climbing plant, often growing in a spiral form, that stretches out and twines around any suitable support.
• Tuber: A thickened underground part of a stem or rhizome, serving as a food reserve and bearing buds from which new plants arise.
• Tunic: A covering or layer of tissue, especially one that encloses an organ or body part.
• Tympanum: A membrane in the ear of some animals, such as frogs, that vibrates in response to sound waves.
• Torpor: A state of decreased physiological activity in an animal, usually by a reduced body temperature and metabolic rate.
• Tarsus: The part of the leg of an insect or other arthropod that is attached to the tibia.
• Tegument: The outer body covering of certain invertebrates, such as nematodes.
• Trophic Cascade: A series of changes in the population sizes of organisms at different trophic levels in a food chain, usually caused by the addition or removal of a key predator.
• Tympanic Membrane: Another term for the eardrum.
• Taxis: Movement of an organism in response to a stimulus such as light or the presence of food.
• Trachea: The windpipe; a tube that connects the pharynx and larynx to the lungs.
• Tendril: A slender, thread-like appendage of a climbing plant, often growing in a spiral form, that stretches out and twines around any suitable support.
• Tuber: A thickened underground part of a stem or rhizome, serving as a food reserve and bearing buds from which new plants arise.
• Tunic: A covering or layer of tissue, especially one that encloses an organ or body part.
• Tympanum: A membrane in the ear of some animals, such as frogs, that vibrates in response to sound waves.
• Torpor: A state of decreased physiological activity in an animal, usually by a reduced body temperature and metabolic rate.
• Tarsus: The part of the leg of an insect or other arthropod that is attached to the tibia.
• Tegument: The outer body covering of certain invertebrates, such as nematodes.
• Trophic Cascade: A series of changes in the population sizes of organisms at different trophic levels in a food chain, usually caused by the addition or removal of a key predator.
• Tympanic Membrane: Another term for the eardrum.

Zoology Terms Starting With U

• Ulna: One of the two long bones in the forearm, located on the side opposite the thumb.
• Umbilical Cord: A flexible cord-like structure containing blood vessels that connects a fetus to the placenta.
• Ungulate: A hoofed mammal.
• Urea: A waste product formed in the liver, filtered out of the blood by the kidneys, and excreted in urine.
• Ureter: A tube that carries urine from the kidney to the bladder.
• Urethra: The duct through which urine is discharged from the bladder to the outside of the body.
• Urinalysis: A test of urine to detect and manage a wide range of disorders.
• Urochrome: A pigment that gives urine its yellow color.
• Urogenital: Relating to the urinary and genital organs.
• Urolithiasis: The formation of urinary stones.
• Uropygium: The fleshy protuberance at the posterior end of a bird’s body, where the tail feathers are attached.
• Urticaria: A skin condition characterized by red, itchy welts, also known as hives.
• Uterus: The organ in female mammals where offspring are conceived and in which they gestate before birth.
• Uvea: The middle layer of the eye, containing the iris, ciliary body, and choroid.
• Uvula: The small fleshy extension at the back of the soft palate that hangs above the throat.
• Ultrasound: Sound waves with frequencies higher than the upper audible limit of human hearing, used in medical imaging.
• Ubiquitin: A small protein that tags other proteins for degradation.
• Uropod: A posterior appendage in crustaceans used for swimming.
• Urostyle: A long bone formed from fused vertebrae at the base of the vertebral column in some amphibians.
• Uracil: One of the four nucleobases in the nucleic acid of RNA.

Zoology Terms Starting With V

• Vacuole: A membrane-bound organelle in cells that stores nutrients, waste products, and other materials.
• Vagus Nerve: A cranial nerve that controls heart rate, digestive tract, and other functions.
• Vampire Bat: A bat species that feeds on the blood of other animals.
• Vascular: Relating to the blood vessels or the circulatory system.
• Vector: An organism that transmits a pathogen from one host to another.
• Venom: A toxic substance produced by some animals, such as snakes and spiders, used to immobilize or kill prey.
• Ventral: Pertaining to the underside or belly of an animal.
• Vertebra: One of the series of small bones forming the backbone.
• Vertebrate: An animal with a backbone.
• Vestigial: Referring to an organ or part that is greatly reduced from the original ancestral form and is no longer functional or is of reduced or altered function.
• Villi: Small, finger-like projections that extend into the lumen of the small intestine to increase surface area for absorption.
• Viviparous: Giving birth to live young that have developed inside the body of the parent.
• Vocal Cords: Folds of tissue in the throat that are key in creating sounds through vocalization.
• Volvox: A genus of chlorophyte green algae that forms spherical colonies.
• Vomer: A thin, flat bone forming part of the nasal septum.
• Vulpine: Relating to or resembling a fox.
• Ventral Fin: A fin located on the underside of a fish.
• Vesicle: A small structure within a cell, consisting of fluid enclosed by a lipid bilayer.
• Vibrissae: Whiskers or long, stiff hairs on the face of some mammals, used as tactile sensors.
• Vermiform: Resembling or having the form of a worm.

Zoology Terms Starting With W

• Worm: A general term for many different elongated, soft-bodied invertebrates, including annelids, nematodes, and flatworms.
• Whiskers: Sensory hairs, also known as vibrissae, found on the faces of many mammals, used to detect nearby objects.
• Wattle: A fleshy, often brightly colored piece of skin hanging from the neck or throat of some birds and mammals.
• Weaning: The process by which a young mammal gradually transitions from mother’s milk to solid food.
• Wingspan: The distance from the tip of one wing to the tip of the other wing in birds, bats, or insects.
• Waterfowl: Birds that live on or around water, including ducks, geese, and swans.
• Whale: A large marine mammal of the order Cetacea, characterized by a streamlined body, flippers, and a blowhole for breathing.
• Wildebeest: A large antelope of the genus Connochaetes, native to Africa, known for its annual migration.
• Woodpecker: A bird of the family Picidae, known for pecking at wood to find insects and create nesting sites.
• Wormhole: A term used in zoology to describe the burrows or tunnels created by worms and other burrowing animals.
• Webbing: The skin that connects the toes of certain animals, such as ducks, frogs, and bats, aiding in swimming or flight.
• Wing: A specialized limb found in birds, bats, and insects, adapted for flight.
• Water Strider: An insect of the family Gerridae, known for its ability to walk on the surface of water.
• Whiptail: A lizard of the genus Cnemidophorus, known for its long, slender tail.
• Wool: The soft, curly hair of sheep and some other mammals, used as a textile fiber.
• Whelp: A term for the young of certain carnivorous mammals, such as wolves or dogs.
• Wasp: An insect of the order Hymenoptera, often known for its narrow waist and sting.
• Whale Shark: The largest species of shark and the largest living fish, known for its filter-feeding habits.
• Wallaby: A small or mid-sized marsupial of the family Macropodidae, similar to kangaroos.
• Worm Cast: The soil or sand excreted by earthworms, often seen as small mounds on the ground.

Zoology Terms Starting With X

• Xylem: The tissue in vascular plants responsible for the conduction of water and nutrients from the roots to the rest of the plant.
• Xenarthra: A superorder of placental mammals that includes armadillos, sloths, and anteaters, characterized by extra joints in their vertebral columns.
• Xiphoid Process: The small, cartilaginous extension of the lower part of the sternum in vertebrates, often becoming ossified in adults.
• Xenograft: A transplant of tissues or organs between different species, often used in medical research.
• Xenopus: A genus of African aquatic frogs, often used as a model organism in biological research.
• Xenobiotic: A chemical substance that is foreign to the biological system, often referring to pollutants or drugs.
• Xanthophyll: A yellow pigment found in the leaves of plants and in the feathers of some birds, contributing to coloration.
• Xenophagy: The consumption of foreign or unusual food, often observed in certain animal species.
• Xiphosura: An order of arthropods that includes horseshoe crabs, known for their hard, horseshoe-shaped carapace.
• Xenodiagnosis: A method of diagnosing parasitic infections by exposing a vector (such as an insect) to a potentially infected host and then examining the vector for the presence of the parasite.
• Xerus: A genus of ground squirrels found in Africa, known for their burrowing behavior.
• Xanthelasma: A condition characterized by yellowish deposits of fat underneath the skin, often around the eyes.
• Xenotime: A rare earth phosphate mineral sometimes studied in paleontology and geology for its fossil content.
• Xanthophores: Cells that contain yellow pigments, contributing to the coloration of fish, amphibians, and reptiles.
• Xenogamy: Cross-pollination between flowers of different plants, a term also applicable in animal reproduction involving different species.
• Xiphosuran: Refers to the group of marine arthropods within the order Xiphosura, commonly known as horseshoe crabs.
• Xenopus laevis: A species of African clawed frog widely used as a model organism in developmental biology and genetics.
• Xiphoid: Resembling a sword; often referring to anatomical structures with a pointed or elongated shape, like the xiphoid process.
• Xenotransplantation: The transplantation of organs or tissues between different species, such as from animals to humans.
• Xylophagy: The feeding behavior of certain animals, like termites and some beetles, that consume wood as their primary food source.

Zoology Terms Starting With Y

• Yolk: The nutrient-rich portion of an egg, which provides nourishment to the developing embryo.
• Yolk Sac: A membranous sac attached to an embryo, providing early nourishment in many vertebrates.
• Yeti Crab: A type of deep-sea crab known for its hairy pincers, found near hydrothermal vents.
• Yellow Perch: A species of freshwater fish, native to North America, known for its distinctive yellow and green coloration.
• Yellow Fever: A viral disease transmitted by mosquitoes, affecting primates and humans, characterized by jaundice.
• Y Chromosome: The sex chromosome typically associated with male characteristics in many animals, including humans.
• Yolk Plug: A structure formed during the development of amphibians, where the yolk is partially exposed on the surface of the embryo.
• Yersinia: A genus of bacteria, some species of which are known to cause diseases such as the plague.
• Yellow Jacket: A type of wasp known for its aggressive behavior and painful sting, often found in North America.
• Yolk Stalk: A tubular structure that connects the yolk sac to the embryo, providing nutrients during early development.
• Yak: A long-haired domesticated bovid found in the Himalayan region, known for its ability to survive in high altitudes.
• Yolkless Egg: An egg that lacks a yolk, often seen in some parasitic animals or certain species of fish.
• Yearling: An animal that is one year old, particularly used to describe young horses or cattle.
• Yellow-Bellied Marmot: A species of marmot native to the mountainous regions of North America, recognizable by its yellowish belly.
• Yolk Protein: A type of protein found in the yolk of eggs, providing essential nutrients to the developing embryo.
• Yellow-Billed Cuckoo: A bird species known for its distinctive yellow bill and migratory behavior in North America.
• Ypsiliform: Shaped like the letter Y; used to describe certain anatomical structures in animals.
• Yellowfin Tuna: A species of tuna known for its bright yellow fins, commonly found in tropical and subtropical oceans.
• Yank: A sudden pull or jerk, sometimes used to describe the quick movements of animals in response to stimuli.
• Yaffle: The characteristic call of the green woodpecker, often used to describe the bird’s laughing-like sound.

Zoology Terms Starting With Z

• Zoology: The scientific study of animals, including their behavior, structure, physiology, classification, and distribution.
• Zooplankton: Tiny floating animals, including both larval stages and adult forms, that drift in water bodies.
• Zygote: The cell formed by the fusion of two gametes, marking the beginning of a new organism’s development.
• Zoonosis: A disease that can be transmitted from animals to humans.
• Zygodactyl: A foot structure in birds where two toes face forward and two face backward, as seen in parrots.
• Zooxanthellae: Symbiotic algae that live within the tissues of corals, providing them with energy through photosynthesis.
• Zebra: A species of African equids known for their distinctive black-and-white striped coats.
• Zonary Placenta: A type of placenta characterized by a belt-like zone of attachment between the mother and fetus, found in some carnivores.
• Zygomatic Arch: The bony arch on the side of the skull, beneath the eye, formed by the zygomatic bone and other bones.
• Zoogeography: The study of the geographical distribution of animal species and populations on Earth.
• Zymogen: An inactive enzyme precursor that requires a biochemical change to become an active enzyme.
• Zygospore: A thick-walled resting spore formed by the fusion of two similar gametes in some fungi and algae.
• Zebrafish: A small freshwater fish species used as a model organism in biological research due to its genetic similarity to humans.
• Zonotrichia: A genus of sparrows, known for their distinctive songs and wide distribution in the Americas.
• Zoophagy: The practice of feeding on other animals, a term often used to describe carnivorous plants and animals.
• Zygomatic Bone: The bone that forms the prominent part of the cheek and contributes to the orbit of the eye.
• Zosteropidae: A family of birds known as white-eyes, characterized by a distinctive ring of white feathers around their eyes.
• Zonation: The distribution of different plant and animal species in distinct horizontal layers or zones, especially in ecosystems like mountains and oceans.
• Zoospore: A motile, flagellated spore found in some algae, fungi, and protozoa, capable of movement.
• Zygomorphic: Referring to flowers or other structures that are symmetrical along one plane only, often seen in orchids and some animals.