Classes of Cnidarians Ms. Springstroh Sources: Mrs. Gallegos /ZOOLOGY/2010Introduction%20to%20Phylum%20Cnidaria.ppt

Classification The phylum Cnidaria is divided into four major classes: Class Hydrozoa Class Scyphozoa Class Cubozoa Class Anthozoa

Class Hydrozoa Hydrozoans have a wide range of forms Appear feathery/bushy Usually made of colonies of tiny polyps

Class Hydrozoa

Hydrazoa (hydras)

Class Hydrozoa Some hydrozoans, such as the Portuguese man- of-war, are actually floating colonies of polyp individuals. One polyp may be gas filled and used as a float. Feeding polyps– each with one long tentacle– are used to catch prey Reproductive polyps

Class Hydrozoa Some corals are hydrozoans Example: Fire coral

Class Scyphozoa (bowl-like) AKA: JELLIES About 95% water >200 species 2-6 month lifespan

Class Scyphozoa Most of the larger jellyfishes Usually take on the medusa form and float Tentacles around the periphery of the bell contain nematocysts used to paralyze prey animals.

Class Scyphozoa Much larger than the floating polyps of class hydrozoa. Diameter of the bell can reach up to 3m in diameter

Examples of Scyphozoa

Class Cubozoa Includes box jellies The medusa is box- shaped Have four evenly- spaced out tentacles or bunches of tentacles Have eyes Biggest stinging threat to swimmers

The Box Jellyfish (Cubozoa)

Class Cubozoa (…box shape) A bit different from scyphozoa in that they’re more venomous, faster swimmers and can “see” better BOX JELLY

Class Anthozoa Class Anthozoa includes the corals and sea anemones which occur only as polyps Solitary or colonial Attach to shells, rocks, mud, or sand

Class Anthozoa Most have symbiotic algae Often provide a home for fish and crabs Nemo lives in an anenome!

Class Anthozoa (flower-like)

Sea Fan Sea Anemone Examples of Anthozoa Coral Sea Anemones

(a) These colonial polyps are members of class Hydrozoa. (b) Many species of jellies (class Scyphozoa), including the species pictured here, are bioluminescent. The largest scyphozoans have tentacles more than 100 m long dangling from a bell-shaped body up to 2 m in diameter. (c) The sea wasp (Chironex fleckeri) is a member of class Cubozoa. Its poison, which can subdue fish and other large prey, is more potent than cobra venom. (d) Sea anemones and other members of class Anthozoa exist only as polyps. Figure 33.7a–d