BIOL 130 Study Guide MT #3 Fall 2025

A set of vocabulary flashcards derived from the lecture notes for BIOL 130, focusing on key terms and definitions relevant to animal evolution and biology.

LUCA

Last Universal Common Ancestor, the most recent organism from which all organisms now living on Earth descend.

Hypotheses on Cambrian Explosion

Various ideas explaining the rapid increase in the diversity of life during the Cambrian period, including ecological, genetic, and geological factors.

Porifera

A phylum of animals known as sponges, which lack true tissues but exhibit features that classify them as animals.

Cnidocytes

Specialized cells in Cnidarians that contain stinging structures used for prey capture.

Bilateria

A group of animals exhibiting bilateral symmetry, triploblasty, and cephalization.

Ecdysis

The process of molting or shedding the exoskeleton in Ecdysozoans.

Coelom

A fluid-filled body cavity that is completely lined with mesoderm, present in some animal groups.

Cephalization

The concentration of sensory organs and nerve cells at the front end of the body, seen in bilateral animals.

Protostomes vs Deuterostomes

Two distinct developmental pathways in animals; protostomes develop mouth first, while deuterostomes develop anus first.

Gastrulation

A phase early in embryonic development when the embryo reorganizes into a multilayered structure.

Molecular phylogenies

Evolutionary trees based on molecular data that reveal genetic relationships among species.

Platyhelminthes

A phylum of flatworms characterized by aacoelomate body plans and often parasitic lifestyles.

Nematoda

A phylum of roundworms, which are often characterized by a tubular digestive system and a pseudocoelom.

Arthropoda

The largest phylum of animals, including insects and crustaceans, characterized by jointed appendages and exoskeletons.

Echinoderms

A phylum of marine animals characterized by radial symmetry and a water vascular system.

Chordates

Animals belonging to the phylum Chordata, defined by features such as a notochord, dorsal nerve cord, and pharyngeal slits.

Somite

A segmented block of mesoderm found in developing embryos of chordates.