Protostome Animals Flashcards

Flashcards reviewing key vocabulary and concepts from the Protostome Animals lecture.

Protostomes

A major clade of triploblastic animals where the 'first' opening (blastopore) becomes the mouth; the anus forms later.

Triploblastic

Animals that have three cell layers: an outer ectoderm, an inner endoderm, and a middle mesoderm.

Anterior Brain

A characteristic of protostomes; the brain surrounds the entrance to the digestive tract.

Ventral Nervous System

A characteristic of protostomes; a nervous system with paired and fused longitudinal nerve cords.

Flatworms (Phylum Platyhelminthes)

Protostomes with dorsal-ventrally flattened bodies and no specialized organs for transporting oxygen; they have a highly branched digestive tract.

Acoelomate

An animal that lacks a coelom, or body cavity. Flatworms are an example.

Leech (Phylum Annelida)

Protostomes that lack parapodia and tentacles; segments at either end are modified to form suckers.

Mollusks (Phylum Mollusca)

A diverse group of protostomes that includes chitons, gastropods, bivalves, and cephalopods.

Chitons

Marine omnivores with eight overlapping calcareous shell plates that scrape algae with a radula.

Radula

A feeding structure in many mollusks used for scraping food.

Gastropods

A class of mollusks including snails, slugs, and nudibranchs; most move by gliding on a muscular foot.

Cephalopods

A class of mollusks including squids, octopi, and nautiluses; they use 'jet propulsion' for movement.

Tardigrades (Phylum Tardigrada)

Extremely small protostomes (water bears) with unjointed legs and a fluid-filled body cavity that acts as a hydrostatic skeleton.

Trilobites (Phylum Trilobitomorpha)

Extinct protostomes with jointed legs, abundant in the fossil record and extinct at the end of the Permian period.

Chelicerates

A subphylum of arthropods including horseshoe crabs and arachnids; they have chelicerae (pincer-like mouthparts) and two tagmata (cephalothorax and abdomen).

Mandibulates

A subphylum of arthropods including myriapods, crustaceans, and hexapods; they have mandibles for chewing and sensory antennae.

Metamorphosis

The process of transformation from an immature form to an adult form in two distinct types: complete or incomplete.