Animal Kingdom – Vocabulary Flashcards

A comprehensive set of vocabulary flashcards covering key terms, structures and examples from the Animal Kingdom lecture, organised to aid quick review and exam preparation.

Animal Classification

Systematic arrangement of over a million described animal species based on shared fundamental features.

Level of Organisation

The degree of structural complexity in an animal—cellular, tissue, organ or organ-system level.

Cellular Level

Organisation in which cells act as loose aggregates with minimal division of labour (e.g., sponges).

Tissue Level

Organisation where similar cells form tissues to perform a common function (e.g., coelenterates).

Organ Level

Tissues assemble into organs specialised for specific tasks (e.g., Platyhelminthes).

Organ-System Level

Organs cooperate in systems to perform major physiological functions (e.g., annelids to chordates).

Incomplete Digestive System

Digestive tract with only one opening serving as mouth and anus.

Complete Digestive System

Digestive tract with separate mouth and anus.

Open Circulatory System

Blood pumped out of heart directly bathes cells in body cavities.

Closed Circulatory System

Blood confined to vessels—arteries, veins and capillaries.

Body Symmetry

Pattern in which an animal’s body can be divided into mirror halves.

Asymmetry

No plane divides the body into equal halves (e.g., most sponges).

Radial Symmetry

Any plane through central axis yields two identical halves (e.g., Coelenterata, Ctenophora, adult echinoderms).

Bilateral Symmetry

Only one plane divides body into identical left and right halves (e.g., annelids, arthropods).

Diploblastic

Having two embryonic germ layers—ectoderm and endoderm—with mesoglea in-between.

Triploblastic

Having three germ layers—ectoderm, mesoderm and endoderm.

Coelom

Mesoderm-lined body cavity between body wall and gut wall.

Coelomate

Animal possessing a true coelom (e.g., annelids, chordates).

Pseudocoelomate

Animal with body cavity not lined by mesoderm, instead scattered pouches (e.g., Aschelminthes).

Acoelomate

Animal lacking a body cavity (e.g., Platyhelminthes).

Segmentation

Serial repetition of body units externally and internally.

Metamerism

Phenomenon of segmented body organisation (e.g., earthworm).

Notochord

Dorsal, mesodermal rod present in chordate embryos; may persist or be replaced by vertebrae.

Porifera

Phylum of multicellular, mostly marine sponges with cellular organisation and canal system.

Ostia

Minute pores on sponge body wall allowing water entry.

Spongocoel

Central cavity of a sponge where water circulates.

Osculum

Large opening through which water exits a sponge.

Choanocyte

Flagellated ‘collar cell’ lining spongocoel and canals of sponges; drives water flow.

Spicule

Hard skeletal element of sponges made of silica or calcium carbonate.

Spongin Fibre

Flexible protein support fibres in some sponges.

Hermaphrodite

Single individual produces both eggs and sperm.

Coelenterata (Cnidaria)

Aquatic, radially symmetrical animals with cnidoblasts and tissue level organisation.

Cnidoblast / Cnidocyte

Stinging cell containing nematocyst for defence and prey capture.

Nematocyst

Capsule inside cnidoblast that ejects a coiled thread for stinging.

Polyp

Sessile, cylindrical cnidarian body form (e.g., Hydra).

Medusa

Free-swimming, umbrella-shaped cnidarian form (e.g., jellyfish).

Metagenesis

Alternation of polyp and medusa generations in some cnidarians.

Ctenophora

Marine ‘comb jellies’ with eight ciliated comb plates and bioluminescence.

Comb Plate

Row of fused cilia used for locomotion in ctenophores.

Bioluminescence

Ability of living organisms to emit light by chemical reaction.

Platyhelminthes

Dorsoventrally flattened acoelomate ‘flatworms’ with organ level organisation.

Flame Cell

Excretory and osmoregulatory cell in flatworms.

Regeneration

Capacity to regrow lost body parts (well-developed in Planaria).

Aschelminthes

Roundworms with pseudocoelom and complete digestive tract.

Roundworm

Common name for aschelminthes; body circular in cross-section.

Annelida

Segmented coelomate worms such as earthworms and leeches.

Parapodia

Lateral paddle-like appendages in aquatic annelids for swimming.

Nephridium

Segmental excretory organ of annelids.

Arthropoda

Largest animal phylum with jointed appendages and chitinous exoskeleton.

Chitinous Exoskeleton

Hard outer covering of arthropods composed mainly of chitin.

Malpighian Tubules

Excretory organs of many terrestrial arthropods.

Book Lungs

Stacked respiratory structures in arachnids (spiders, scorpions).

Book Gills

Gill plates in horseshoe crabs for aquatic respiration.

Mollusca

Soft-bodied animals often protected by calcareous shells.

Mantle

Soft fold of dorsal body wall in molluscs that secretes the shell.

Mantle Cavity

Space between mantle and visceral hump; houses gills.

Visceral Hump

Internal mass containing organs in molluscs.

Radula

Rasping, tongue-like feeding organ unique to molluscs.

Echinodermata

Marine animals with spiny skin, calcareous ossicles and water vascular system.

Calcareous Ossicle

Limestone plate forming echinoderm endoskeleton.

Water Vascular System

Network of fluid-filled canals used for locomotion and feeding in echinoderms.

Hemichordata

Worm-like marine phylum with rudimentary notochord-like stomochord.

Stomochord

Rod-like structure in hemichordate collar region resembling a notochord.

Proboscis

Anterior, muscular region of hemichordates used in burrowing and feeding.

Collar

Middle body region of hemichordates between proboscis and trunk.

Trunk (Hemichordata)

Posterior body region containing most organs.

Chordata

Phylum possessing notochord, dorsal hollow nerve cord and pharyngeal gill slits.

Dorsal Hollow Nerve Cord

Neural tube on dorsal side of chordates; develops into brain and spinal cord.

Pharyngeal Gill Slits

Paired openings in pharynx for filter feeding or respiration in chordates.

Post-Anal Tail

Muscular tail extending beyond anus in chordate embryos or adults.

Protochordate

Collective term for subphyla Urochordata and Cephalochordata.

Urochordata

Tunicates with notochord only in larval tail phase (e.g., Ascidia).

Cephalochordata

Lancelets with notochord extending from head to tail throughout life.

Vertebrata

Subphylum with vertebral column replacing notochord in adults.

Cyclostomata

Jawless, ectoparasitic vertebrates such as lampreys and hagfishes.

Chondrichthyes

Cartilaginous fishes with placoid scales and ventral mouth (e.g., sharks).

Placoid Scale

Tooth-like dermal scale of cartilaginous fishes forming powerful teeth.

Osteichthyes

Bony fishes with operculum-covered gills and buoyancy-regulating air bladder.

Operculum

Bony flap covering gills in bony fishes.

Air Bladder

Gas-filled sac in many bony fishes that maintains buoyancy.

Amphibia

Cold-blooded vertebrates living both on land and in water, with moist skin.

Cloaca

Common chamber for digestive, urinary and reproductive tracts in amphibians.

Poikilothermous

Having variable body temperature influenced by environment; cold-blooded.

Reptilia

Creeping vertebrates with dry, cornified scales; mostly oviparous.

Cornified Skin

Keratinised, dry skin of reptiles preventing water loss.

Aves

Birds—warm-blooded vertebrates with feathers, beak and pneumatic bones.

Pneumatic Bone

Hollow, air-filled bone in birds that reduces weight.

Crop

Food-storage pouch in bird oesophagus.

Gizzard

Muscular, grinding stomach chamber in birds.

Homoiothermous

Maintaining constant internal body temperature; warm-blooded.

Mammalia

Warm-blooded vertebrates with hair, mammary glands and mostly viviparous reproduction.

Mammary Gland

Milk-secreting gland of mammals for nourishing young.

Viviparous

Giving birth to live young after internal development.

Oviparous

Laying eggs that develop and hatch outside the mother’s body.

Ectoparasite

Organism living externally on host and deriving nutrition (e.g., lice, lamprey).

Dioecious

Species in which males and females are separate individuals.

Metameric Segmentation

Division of body into serial, similar units, characteristic of annelids.

Book Gills

Respiratory structures in Limulus consisting of leaf-like gill plates.

Book Lungs

Stacked internal plates for gas exchange in arachnids.

Statocyst

Sensory organ of balance in crustaceans.