YAKEEN NEET 2027 Animal Kingdom - Non-Chordata Flashcards

This set of vocabulary flashcards covers the fundamental concepts, levels of organization, and defining characteristics of various non-chordate phyla as detailed in the Animal Kingdom lecture notes.

Cellular level of organisation

A level of organisation seen in sponges where cells are arranged in loose cell aggregates and show division of labour.

Tissue level of organisation

An organisation where cells performing the same function are arranged into groups.

Organ system level of organisation

A level of organisation observed in higher animals such as annelids, molluscs, and chordates where tissues are grouped into systems.

Complete digestive system

A digestive system that possesses $2$ openings, namely a mouth and an anus.

Incomplete digestive system

A digestive system that has only a single opening that serves as both mouth and anus.

Open circulatory system

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

Closed circulatory system

A system where blood is circulated through a tube system consisting of arteries, veins, and capillaries.

Radial symmetry

Symmetry where any plane passing through the central axis of the body divides the organism into $2$ equal halves, as seen in Coelenterata, Ctenophora, and adult Echinodermata.

Bilateral symmetry

Symmetry where the body can be divided into identical left and right halves in only $1$ plane.

Diploblastic

Animals with $2$ embryonic layers, an external ectoderm and an internal endoderm, with an undifferentiated mesoglea in between.

Triploblastic

Animals whose developing embryo has $3$ differentiated embryonic layers: ectoderm, endoderm, and mesoderm.

Coelom

A body cavity that is lined by mesoderm, located between the body wall and the gut wall.

Pseudocoelomate

Animals, such as Aschelminthes, whose body cavity is not lined by mesoderm.

Acoelomate

Animals that lack a body cavity, such as those in the phylum Platyhelminthes.

Metamerism

True segmentation of the body, which is first witnessed in the phylum Annelida.

Notochord

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

Spongocoel

The central cavity in poriferans (sponges) which is lined by flagellated cells.

Choanocytes

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

Ostia

Minute pores in the body wall of a sponge through which water enters the body.

Osculum

An opening in sponges through which water leaves the spongocoel to the exterior.

Spicules

Components that, along with spongin, make up the skeleton of animals in the phylum Porifera.

Metagenesis

The alternation of generation seen in cnidarians like Obelia, where polyps produce medusae asexually and medusae form polyps sexually.

Hypostome

The gastrovascular opening found in Coelenterates.

Flame cells

Specialized excretory cells found in Platyhelminthes, such as Fasciola, that help in osmoregulation and excretion.

Parapodia

Lateral appendages found in some members of Phylum-Annelida that are used for swimming.

Statocysts

The balancing organs found in members of the phylum Arthropoda.

Malpighian tubules

Excretory organs present in arthropods used for the removal of nitrogenous waste.

Radula

A file-like rasping organ used for feeding, found in the mouth of animals in the phylum Mollusca.

Stomochord

A rudimentary structure present in the collar region of hemichordates, similar to the notochord.

Proboscis gland

The excretory organ located in the proboscis region of members of phylum Hemichordata.