The Characteristics of Phylum Cnidaria

Portuguese Man-Of-War Phylum Cnidaria Class Anthozoa Class Hydrozoa Class Scyphozoa Class Cubozoa Corals Anemones Hydra Portuguese Man-Of-War Stinging Limu Fire Coral True jellyfish Box jellies Sea wasps

Characteristics of Phylum Cnidaria radial symmetry blind sac gut (= coelenteron or gastrovascular cavity) diploblastic with mesoglea polyp and medusa body forms nematocysts (= specialized stinging capsules) nerve net lack excretory, circulatory & respiratory systems complex life cycle many colonial forms exhibiting polymorphism

oral Radial Symmetry Polyp aboral

Jellyfish Phylum Cnidaria Radial Symmetry Jellyfish Phylum Cnidaria Medusa

Blind Sac Gut

Diploblastic- two germ layers Phylum Cnidaria

Nematocysts

Nematocyst Picture Nematocyst

More Nematocysts http://www.youtube.com/watch?NR=1&v=-Tp38DUjUnM&feature=endscreen

Nerve Net

Diffusion Across the Body Wall

Sea Anemones

Circulation in a Moon Jellyfish

The Cnidarian Life Cycle

Coloniality Coral Phylum Cnidaria

Class Hydrozoa (Gr. hydra, water serpent) polyps and medusa stage, although polyp stage is dominant. gut cavity of polyp is simple, lacking a pharynx and not divided by mesenteries. tetramerous (four-part) radial symmetry. gonads are ectodermal (found in the epidermis). medusa stage may possess specialized balance organs called statocysts and photosensitive organs called ocelli. solitary or colonials; some colonial forms highly polymorphic. includes hydroids (“stinging limu”), fire coral, pink coral, and siphonophores.

The Cnidarian Life Cycle The Hydrozoan Life Cycle

Hydrozoan Colony

Hydrozoan Colonies “Stinging Limu”

Hydrozoan Medusa

Hydrozoan Medusa

Hydrocorals

Fire Coral

By-the-Wind-Sailor A Floating Colony of Polyps

Coloniality and Polymorphism

Poly,orphism in the Portuguese Man- of-War

Class Scyphozoa (Gr. skyphos, cup) medusae stage dominate. polyp stage (scyphistoma) goes through strobilization to produce young medusa. bell margin lacks a velum. tetramerous (= four-part) radial symmetry. gut divided into a complex system of radial canals. some with a simple single mouth, but many with thousands of microscopic “mouths” at the ends of oral arms. gonads endodermal (found in the gastrodermis). specialized sense organs called rhopalia with ocelli & statocysts . includes some 200 marine species. "true" sea jellies.

Moon Jelly Anatomy

Scyphozoan Life Cycle strobila scyphistoma

Sea Jellies

Class Cubozoa medusae dominate stage. (Gr. kybos, a cube) medusae dominate stage. polyp stage develops directly into medusa. bell margin with a velarium. tetramerous (= four-part) radial symmetry; bell cube-shaped with tentacles arising from each corner. gonads endodermal (found in the gastrodermis). specialized sense organs called rhopalia with ocelli & statocysts . includes some 15 marine species. includes box jellies and sea wasps.

Seawasp Box Jellies

Box Jelly Anatomy

Class Anthozoa Polyp stage only Blind sac gut (Gr. anthos, flower) Polyp stage only Blind sac gut mesenteries radiate inwards from the body wall gonads endodermal, borne on the mesenteries hexamerous (6-part) or octamerous (8-part) radial symmetry or biradial sea anemones, “true” stony corals, sea fans, sea pens, organ pipe coral, precious black coral, & zoanthids

Subclass Zoantharia Order Actinaria Sea Anemones

Sea Anemone Anatomy

Subclass Hexacorallia Order Zoanthidae No hard skeleton May be tough and leathery Shallow water forms Encrusting forms Some with zooxanthellae Polyp stage only

Black Coral & Wire Coral Subclass Hexacorallia Order Antipatheria Black Coral & Wire Coral Black coral Wire coral

Subclass Hexacorallia Order Scleractinia “True” Stony Corals Hermatypic- reef building, zooxanthellae Common species: Acroporidae- table Acroporidea- rice Agariciidae- flat lobe, corrugated Faviidae- crust, ocellated Fungiidae- humpback, mushroom Pocilloporidae- lace, antler, cauliflower Poritidae- finger, lobe, plate

“True” Stony Corals lobe finger mushroom Porites rus

Octocorals Sea pen

Organ pipe coral