All contain nematocysts-stinging structures Phylum Cnidaria All contain nematocysts-stinging structures
Cnidarians Jellies, Anemones, Corals Dimorphism: Two body shapes during life cycle. (Polyp & Medusa) Gastrovascular cavity (digestive) Carnivores Primitive nerve net Two distinct tissue layers: Epidermis & Gastrodermis Cnidocyte (Stinging cells) in tentacles Radial Symmetry
The Polyp and Medusa Stages Epidermis Mesoglea Gastroderm Tentacles Mouth/anus Gastrovascular cavity Mesoglea Gastrovascular cavity Mouth/anus Tentacles Polyp Medusa
Feeding Paralyze prey and pulls into mouthgastrovascular cavity Undigested materials passed out through mouth/anus
Respiration, Circulation, Excretion Diffusion through body walls Nerve net-network of nerve cells to detect stimuli Statocysts to determine gravity direction Ocelli as eyespots to detect light Response
Movement Hydrostatic skeleton-muscles w/ water enable movement Body contracts to force water out, moving jellyfish in opposite direction.
Reproduction and Life cycle Most cnidarians reproduce both sexually and asexually. External fertilization
Jellyfish Life Cycle Female medusa (2N) MEIOSIS Fertilization occurs in the open water, producing many diploid zygotes. Egg (N) Adult medusas reproduce sexually by releasing gametes into the water. FERTILIZATION Sperm (N) Each zygote grows into a ciliated larva. The larva eventually attaches to a hard surface and develops into a polyp. Zygote (2N) Male medusa (2N) Young medusa Swimming larva Polyp The polyp buds to release young medusas. Haploid Diploid Budding polyp
Classes of Cnidaria Hydrozoa (Serpent Animals) Scyphozoa (Cup Animals) Anthozoa (Flower Animals)
Class Hydrozoa Both body forms: polyp and medusa Reproduce sexually as medusas. Example: Portuguese Man Of War
Class Scyphozoa True jellies Medusa form during most of its life cycle. Lions Mane is the most common in L.I.S. Butter fish lives in its tentacles.
Moon Jelly Free swimming Up to 30 cm wide Found in intertidal zone Found in L.I.S. (Also in the tanks of Maritime Aquarium)
Sea Wasp (another scyphozoan ex.) Known as box jellyfish Most powerful venom in the world Lives in Australia Can be up to 60 meters in length
Class Anthozoa They are individual or colonies of polyps found in coastal waters. No medusa stage. Examples: Sea anemones,Hard corals, sea fans
Northern Red Anemone 7.5 cm high, 12.5 cm wide Attach to rocks under rockweed. Found in subtidal zones
Striped Anemone 2 cm high .5 cm wide Found on lower rocks on sheltered shores. Can tolerate reduced salinity.
Sea fans
Hard corals
Phylum Ctenophora Ctenophores Common name: Comb jellies Contain eight rows of comb plates made of cilia used for locomotion (ciliary combs) Bioluminescent No stinging cells They feed on plankton
Comb Jellies