Download - Cnidaria & Ctenophora. Cnidaria Radially symmetrical Tentacles contain nematocysts (stinging cells)
Cnidaria & Ctenophora
Cnidaria
• Radially symmetrical
• Tentacles contain nematocysts (stinging cells)
Cnidaria• Medusa: free-swimming
• Polyp: sessile
Class Anthozoa
• 6000 species, including sea anemones, corals and sea fans.
• May be solitary or colonial
• Hexacorallia: 6-part symmetry, hard corals
• Octocorallia: 8-part symmetry, soft corals
Class Hydrozoa
• 2700 species, including Portuguese man-of-war, and fire coral
• Both polyp and medusa
• Polyps may be for feeding, defense, and reproduction
Order Siphonophora
• Drifting colonies that inhabit tropical and sub-tropical regions– Physalia (Portuguese
man-of-war)– blue sail-like float– tentacles may reach
several meters below the float.
Class Scyphozoa
• 200 species of jellyfish• Cold to tropical water• 2-40cm (up to 2m)• Most jellies can swim
horizontally and vertically• Aurelia (Moon jelly)• Cassiopea or upside-
down jellyfish (filter feed / zooxanthellae)
Class Cubozoa
Box jelly or sea wasp (Chironex fleckeri)
• Strong toxin, causes immediate, extreme pain
• Death can occur 3-20 min after a sting
Phylum Ctenophora
• 8 comb rows• Have
colloblasts: sticky ends that are used to capture prey
• Catch food with tentacles
Comb jellies
• Bioluminescent• All marine• Most are pea-size
to golf ball-size