Animal Kingdom - Basis of Classification and Phyla

Comprehensive vocabulary flashcards detailing the bases of animal classification and key structural and functional characteristics of animal phyla and vertebrate classes based on lecture notes.

Cellular Level of Organisation

A level of organization where the body is made up of loose cell aggregates with no coordination among cells to form tissues, and cells simply work individually (e.g., Sponges).

Tissue Level of Organisation

A level of organization where cells performing the same function are organized into tissues (e.g., Coelenterates such as Hydra).

Organ Level of Organisation

A level of organization where tissues group together to form organs, each performing a specific function (e.g., Platyhelminthes and higher phyla).

Organ System Level of Organisation

A level of organization where organs work together to form organ systems, each responsible for a specific function like digestion (e.g., Annelids, Arthropods, Chordates, Molluscs, and Echinoderms).

Incomplete Digestive System

A digestive system that has only one single opening that acts as both mouth and anus (e.g., Platyhelminthes).

Complete Digestive System

A more efficient digestive system that possesses two distinct openings: a mouth and an anus.

Closed Circulatory System

A circulatory system where blood flows within closed vessels (arteries, capillaries, and veins), which is more efficient.

Open Circulatory System

A circulatory system where blood is pumped out of the heart directly into open spaces to bathe tissues, making it less efficient.

Asymmetry

A body plan where no plane passing through the center can divide the body into equal halves due to irregular body shape (e.g., Sponges).

Bilateral Symmetry

A body plan where the body can be divided into identical left and right halves in only one plane (e.g., Arthropods and Annelids).

Radial Symmetry

A body plan where any plane passing through the central axis divides the animal into two identical halves (e.g., Coelenterates, Ctenophores, and Echinoderms).

Germ Layer

The primary layers of cells that form during early embryonic development.

Diploblastic

Animals that develop from two germ layers during embryonic development: ectoderm and endoderm (e.g., Hydra, jellyfish).

Triploblastic

Animals that develop from three germ layers: ectoderm, mesoderm, and endoderm (e.g., Platyhelminthes to Chordates).

Coelom

The fluid-filled body cavity located between the body wall (outer tube) and the gut wall (inner tube).

Coelomates

Animals possessing a true coelom that is completely lined by mesoderm tissue (e.g., Arthropods and Chordates).

Acoelomates

Animals that lack a body cavity because the coelom region is entirely filled with tissues (e.g., Platyhelminthes / flatworms).

Pseudocoelomates

Animals whose body cavity is not fully lined by mesoderm, appearing instead as scattered pouches between the ectoderm and endoderm (e.g., Aschelminthes / roundworms).

Notochord

A mesodermally derived rod-like structure formed on the dorsal (back) side during embryonic development that provides support to the developing embryo.

Metamerism

The phenomenon in which an animal's body is externally and internally divided into a repeating series of linear sections or segments called metameres (e.g., Earthworm).

Ostia

Tiny pores on the body wall of sponges (Phylum Porifera) through which water enters into the central cavity.

Spongocoel

The central body cavity of sponges into which water flows from the ostia.

Osculum

The large outlet opening in sponges through which water exits the central spongocoel.

Choanocytes

Collar cells that line the spongocoel and canals in sponges, aiding in water circulation and food capture.

Hermaphrodite

An organism that possesses both male and female reproductive cells/organs within the same individual.

Indirect Development

A developmental process in which an offspring hatches or is born in a distinctly immature, physically different larval form that undergoes metamorphosis into an adult.

Cnidocytes

Specialized stinging cells (also called cnidoblasts) on tentacles and body surfaces of Cnidarians containing nematocysts (stinging capsules) used for anchorage, prey capture, and defense.

Hypostome

A raised central structure in Cnidarians that features a single opening serving as the mouth.

Polyp

A sessile and cylindrical body form of Cnidarians (e.g., Hydra, Adamsia).

Medusa

An umbrella-shaped, free-swimming body form of Cnidarians (e.g., Aurelia or jellyfish).

Comb Plates

Eight external rows of ciliated plates found on the body of Ctenophores that assist in locomotion.

Bioluminescence

The property of a living organism to emit light, prominently exhibited by Phylum Ctenophora.

Flame Cells

Specialized excretory cells found in Platyhelminthes that function in osmoregulation and excretion.

Parapodia

Lateral appendages found in aquatic annelids (e.g., Nereis) that aid in swimming.

Nephridia

Excretory structures present in Phylum Annelida responsible for osmoregulation and waste removal.

Chitinous Exoskeleton

A hard outer body covering made of chitin present in Phylum Arthropoda that protects the organism.

Malpighian Tubules

Excretory organs in Arthropods used for eliminating metabolic wastes.

Statocysts

Specialized sensory organs for balance present in Arthropods.

Radula

A rasping organ found in the mouth of molluscs used for feeding.

Mantle Cavity

The space between the visceral hump and the mantle in Mollusca containing gills for respiration and excretion.

Water Vascular System

A unique hydraulic system in Echinoderms that facilitates locomotion, respiration, and food capture/transport.

Stomochord

A rudimentary structure present in the collar region of Hemichordata that is structurally similar to a notochord.

Proboscis Gland

The specialized excretory organ located in the anterior proboscis of Hemichordates.

Protochordates

An informal group comprising Urochordata and Cephalochordata, which are exclusively marine chordates.

Cyclostomata

A class of jawless (Agnatha) ectoparasitic vertebrates featuring an elongated body with 6-15 pairs of gill slits and a circular sucking mouth without jaws (e.g., Petromyzon, Myxine).

Chondrichthyes

A class of marine fishes possessing a cartilaginous endoskeleton, placoid scales, powerful jaws, a ventral mouth, persistent notochord, and no air bladder (e.g., Scoliodon, Carcharodon).

Osteichthyes

A class of bony fishes found in marine and fresh water, characterized by cycloid/ctenoid scales, a terminal mouth, an operculum covering 4 pairs of gills, and an air bladder.

Cloaca

A common chamber in amphibians into which the alimentary tract, urinary tract, and reproductive tracts open before exiting to the exterior.

Tympanum

A membrane-bound structure that represents the ear in amphibians and reptiles.

Pneumatic Bones

Hollow long bones filled with air cavities found in Class Aves (birds) to reduce body weight for flight.

Mammary Glands

Unique milk-producing glands present in mammals used for nourishing young offspring.