Animal Evolution and Characteristics

Flashcards covering key vocabulary terms and definitions related to animal evolution, characteristics, and development.

Choanoflagellate

A modern-day sponge-like organism that uses filter-feeding cells.

Ediacaran biota

A rich fossil area containing some of the first true animal fossils.

Heterotrophic

Animals that ingest food for energy, unlike fungi which digest externally.

Multicellular

All animals are made up of multiple cells, as opposed to unicellular organisms like protists.

Collagen

A strong, flexible polymer found in animal cells, absent in plants.

Bilateral symmetry

A body plan that can be divided into two equal halves along one plane, typical of more advanced animals.

Cephalization

The development of a head and sensory organs at one end of the body, associated with bilateral symmetry.

Triploblastic

Animals that develop from three embryonic tissues: ectoderm, mesoderm, and endoderm.

Blastula

An early stage of embryo development characterized by an open ball of cells.

Protostome

A developmental pattern where the mouth forms from the blastopore; examples include insects and mollusks.

Deuterostome

A developmental pattern where the anus forms from the blastopore; examples include humans and sea stars.

Hydrostatic skeleton

A structure found in certain animals, such as cnidarians, that uses water pressure to maintain shape.

Cnidocyte

The stinging cell found on the tentacles of cnidarians, used for capturing prey.

Mesoderm

The middle tissue layer in a triploblastic animal that develops into muscles and skeletal tissues.

Polyp

The stationary body form of cnidarians, which can anchor to substrates and extends tentacles for feeding.

Medusa

The free-floating body form of cnidarians, characterized by its bell shape and ability to swim.

Zooxanthellae

Photosynthetic dinoflagellates that live symbiotically inside corals, contributing to their energy acquisition.

Acoelomate

Animals lacking a body cavity, which must find alternative systems for organ placement.

Pseudocoelomate

Animals with a false body cavity, not completely lined by mesoderm.

Eucoelomate

Animals that possess a true coelom, allowing for the development of well-structured organ systems.