Invertebrate Biology: Cnidarians and Annelids Overview

Cnidaria

Phylum including corals, jellyfish, and anemones.

Anthozoa

Class of Cnidaria; includes corals and anemones.

Scyphozoa

Class of Cnidaria; true jellyfish.

Cubozoa

Class of Cnidaria; box jellyfish.

Hydrozoa

Class of Cnidaria; includes hydra and Portuguese Man O' War.

Polymorphic

Organisms with multiple body forms in life cycle.

Gastrozooid

Feeding structure in colonial cnidarians.

Gonozooid

Reproductive structure in colonial cnidarians.

Coenosarc

Living tissue connecting zooids in colonial cnidarians.

Ctenophora

Phylum of comb jellies; transparent and gelatinous.

Platyhelminthes

Phylum including flatworms, with ~20,000 species.

Turbellarians

Free-living flatworms within Platyhelminthes.

Cestoda

Class of Platyhelminthes; includes tapeworms.

Trematoda

Class of Platyhelminthes; includes flukes.

Cephalization

Development of a head region with sensory organs.

Proglottids

Segments of tapeworms containing reproductive organs.

Annelida

Phylum of segmented worms; includes earthworms.

Oligochaeta

Class of Annelida; includes earthworms.

Polychaeta

Class of Annelida; marine worms with bristles.

Hirudinea

Class of Annelida; includes leeches.

Clitellum

Reproductive structure in some annelids for egg storage.

Chaetae

Bristle-like structures on annelids for movement.

Hydrostatic skeleton

Fluid-filled coelom providing structural support.

Planaria

Example of free-living flatworm in Platyhelminthes.

Dugesia

Genus of planarians; nonparasitic flatworms.

Venus' girdle

Ctenophore species known for ciliated rows.

Comb jellies

Gelatinous marine predators with cilia for movement.

Cnidocyte

Specialized cell in cnidarians for capturing prey.

Medusa

Free-swimming stage in the life cycle of cnidarians.