Invertebrates: Key Vocabulary and Concepts

Vocabulary and definitions from the lecture on invertebrates.

Invertebrates

Animals that lack a backbone; account for 95% of known animal species.

Eumetazoa

Clade including all animals with true tissues, excluding sponges.

Cnidocytes

Unique cells found in cnidarians that function in defense and prey capture.

Gastrovascular cavity

Central digestive compartment found in cnidarians with a single opening functioning as both mouth and anus.

Choanocytes

Flagellated collar cells that generate water currents and ingest food in sponges.

Porifera

Phylum that includes sponges, characterized by a porous body and lack of true tissues.

Amoebocytes

Cells in sponges that transport nutrients and produce materials for skeletal fibers.

Bilateral symmetry

Body plan in which the left and right sides are mirror images; typical of most animal phyla.

Radial symmetry

Body plan in which body parts are arranged around a central axis; characteristic of cnidarians.

Trochophore

Ciliated larval stage present in the life cycle of many aquatic molluscs.

Metamorphosis

Developmental process where an organism transforms from an immature form to an adult form, commonly seen in insects.

Exoskeleton

Hard outer structure protecting the body of arthropods, made primarily of chitin.

Open circulatory system

Circulatory system where fluid called hemolymph is circulated into spaces surrounding tissues.

Lophophore

Horseshoe-shaped, suspension-feeding organ bearing ciliated tentacles, found in lophophorates.

Echinodermata

Phylum including slow-moving or sessile marine animals like sea stars and sea urchins, characterized by radial symmetry.

Phylum Chordata

Phylum that includes vertebrates and some invertebrate subphyla, characterized by features such as a notochord and dorsal, hollow nerve cord.

Annelids

Segmented worms belonging to the phylum Annelida, possessing bodies made of fused rings.

Tapeworms

Parasitic flatworms that lack a digestive system and absorb nutrients directly from their host.

Decapods

Large crustaceans, including lobsters, crabs, and shrimp, distinguished by ten appendages.