Animal Kingdom Classification and Phyla

Practice flashcards covering the basis of classification and the distinct characteristics of animal phyla and classes from the lecture notes.

Cellular level of organisation

A pattern of cell arrangement where cells are loose aggregates, as seen in sponges.

Tissue level of organisation

An arrangement where cells performing the same function are grouped into tissues, characteristic of coelenterates.

Organ level of organisation

A level of organisation exhibited by Platyhelminthes where tissues are grouped together to form specialised functional units.

Incomplete digestive system

A digestive system with a single opening to the outside of the body that serves as both mouth and anus, found in Platyhelminthes.

Open circulatory system

A system in which blood is pumped out of the heart and the cells and tissues are directly bathed in it.

Closed circulatory system

A system in which blood is circulated through a series of vessels of varying diameters including arteries, veins, and capillaries.

Radial symmetry

A body plan where any plane passing through the central axis divides the organism into two identical halves, found in coelenterates, ctenophores, and echinoderms.

Bilateral symmetry

A body plan where the body can be divided into identical left and right halves in only one plane, exhibited by annelids and arthropods.

Diploblastic

Animals in which cells are arranged in two embryonic layers: an external ectoderm and an internal endoderm.

Mesoglea

An undifferentiated layer present between the ectoderm and the endoderm in diploblastic animals.

Triploblastic

Animals whose developing embryo has three germinal layers: ectoderm, endoderm, and a middle mesoderm.

Coelom

A body cavity which is lined by mesoderm.

Pseudocoelom

A body cavity where the mesoderm is present as scattered pouches between the ectoderm and endoderm, found in Aschelminthes.

Acoelomates

Animals in which the body cavity is absent, such as Platyhelminthes.

Metamerism

The phenomenon of serial repetition of at least some organs in segmented animals like earthworms.

Notochord

A mesodermally derived rod-like structure formed on the dorsal side during embryonic development in some animals.

Choanocytes

Also known as collar cells, these line the spongocoel and the canals in members of Phylum Porifera.

Cnidoblasts

Stinging capsules or nematocysts present on the tentacles and body of cnidarians used for anchorage, defense, and prey capture.

Metagenesis

The alternation of generations in cnidarians where polyps produce medusae asexually and medusae form polyps sexually.

Bioluminescence

The property of a living organism to emit light, a characteristic well-marked in ctenophores.

Flame cells

Specialised cells in flatworms that help in osmoregulation and excretion.

Parapodia

Lateral appendages found in aquatic annelids like Nereis that assist in swimming.

Radula

A file-like rasping organ for feeding found in the mouth of molluscs.

Water vascular system

A distinctive feature of echinoderms that facilitates locomotion, capture and transport of food, and respiration.

Stomochord

A rudimentary structure in the collar region of hemichordates that is similar to a notochord.

Protochordates

A group comprising subphyla Urochordata and Cephalochordata which are exclusively marine.

Gnathostomata

A division of Vertebrata comprising animals that possess jaws.

Poikilothermous

Cold-blooded animals that lack the capacity to regulate their body temperature.

Operculum

A gill cover found in Osteichthyes that protects the gills.

Cloaca

A common chamber in amphibians into which the alimentary canal, urinary, and reproductive tracts open.

Homoiothermous

Warm-blooded animals that are able to maintain a constant body temperature, such as Aves and Mammalia.

Pneumatic bones

Long bones that are hollow with air cavities, found in the endoskeleton of birds.