Phylum Cnidaria

Cnidaria & Ctenophora

CnidariaRadially symmetricalTentacles contain nematocysts (stinging cells)

CnidariaMedusa: free-swimming

Polyp: sessile

Class Anthozoa6000 species, including sea anemones, corals and sea fans.May be solitary or colonialHexacorallia: 6-part symmetry, hard coralsOctocorallia: 8-part symmetry, soft corals

Class Hydrozoa2700 species, including Portuguese man-of-war, and fire coralBoth polyp and medusaPolyps may be for feeding, defense, and reproduction

Order SiphonophoraDrifting colonies that inhabit tropical and sub-tropical regionsPhysalia (Portuguese man-of-war)blue sail-like floattentacles may reach several meters below the float.

Class Scyphozoa

200 species of jellyfishCold to tropical water2-40cm (up to 2m)Most jellies can swim horizontally and verticallyAurelia (Moon jelly)Cassiopea or upside-down jellyfish (filter feed / zooxanthellae)

Class Cubozoa Box jelly or sea wasp (Chironex fleckeri)Strong toxin, causes immediate, extreme painDeath can occur 3-20 min after a sting

Phylum Ctenophora8 comb rowsHave colloblasts: sticky ends that are used to capture preyCatch food with tentacles

Comb jelliesBioluminescentAll marineMost are pea-size to golf ball-size