Invertebrate Biology: Cnidarians and Annelids Overview

Cnidaria

Phylum containing jellyfish, corals, and anemones.

Anthozoa

Class of Cnidaria, includes corals and anemones.

Scyphozoa

Class of Cnidaria, known as true jellyfish.

Cubozoa

Class of Cnidaria, includes box jellyfish.

Hydrozoa

Class of Cnidaria, includes hydras and Portuguese Man O' War.

Gastrozooid

Feeding polyp in colonial cnidarians.

Gonozooid

Reproductive polyp in colonial cnidarians.

Coenosarc

Common tissue connecting polyps in colonies.

Ctenophora

Phylum of comb jellies, transparent and ciliated.

Platyhelminthes

Phylum of flatworms, includes free-living and parasitic forms.

Turbellarians

Free-living flatworms, e.g., planarians.

Cestoda

Class of Platyhelminthes, includes tapeworms.

Trematoda

Class of Platyhelminthes, includes flukes.

Proglottids

Segments of tapeworms containing reproductive organs.

Annelida

Phylum of segmented worms, includes earthworms.

Oligochaetes

Class of Annelida, includes earthworms with few bristles.

Polychaetes

Class of Annelida, marine worms with bristles.

Hirudinea

Class of Annelida, includes leeches.

Chaetae

Bristle-like structures on annelids for locomotion.

Coelom

Body cavity functioning as a hydrostatic skeleton.

Cephalization

Development of a head region with sensory organs.

Blastocoelomate

Organisms with a body cavity not lined by mesoderm.

Planaria

Genus of free-living flatworms, model organism.

Dugesia sp.

Common genus of planarians, studied for regeneration.

Venus' girdle

Ctenophore known for its ciliated rows.

Sea gooseberry

Common name for Pleurobrachia pileus, a ctenophore.

Hydra

Freshwater cnidarian known for regeneration.

Obelia

Colonial hydrozoan, important lab example.