Animal Evolution and Classification

These flashcards cover key vocabulary and concepts related to animal evolution, classification, and the features of different phyla based on the lecture notes.

Cambrian explosion

A rapid diversification of animal life that occurred approximately 585-525 million years ago.

Hox genes

Homeotic genes expressed in developing embryos that regulate the positions of body parts and contain homeobox sequences.

Phylum Porifera

The phylum that includes sponges, characterized by porous bodies and simple cellular structure without true tissues.

Choanocytes

Flagellated cells lining the inside of the spongocoel that create water currents and capture food particles.

Eumetazoa

Animals with true tissues, distinguished from Parazoa (sponges) which lack true tissues.

Gastrovascular cavity

A central digestive compartment in cnidarians that serves both digestive and circulatory functions.

Cnidocytes

Stinging cells found in cnidarians that defend against predators and capture prey.

Bilateral symmetry

A body plan in which the left and right sides of the organism are mirror images.

Triploblastic

Organisms with three germ layers: ectoderm, endoderm, and mesoderm, typically associated with bilateral symmetry.

Regeneration

The ability of some organisms, such as sponges, to regrow lost parts or form new individuals from fragments.