kingdom animalia phylum cnidaria. characteristics radial symmetry diploblastic organization, 2...
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Kingdom Kingdom AnimaliaAnimalia
Phylum CnidariaPhylum Cnidaria
CharacteristicsRadial symmetryDiploblastic organization, 2 official tissue layers
Gelatinous MesogleaGastrovascular cavityNerve netCnidocytes called nematocysts
Coilednematocyst
Reproduction/Life Cycle
Most alternate generations between polyp and medusa form
Polyp – asexual, sessile, produce more polyps (colonial) or medusae (pl.) by budding…
Medusae – dioecious & free swimming; fertilized larva (Planula) settles & forms a polyp
CnidariansCnidarians
Feeding
Use nematocysts to stun or kill prey
Tentacles bring food to mouth
Digested in gastrovascular cavity
Support and Locomotion
Hydrostatic Skeleton (supported by water)
Polyps – somersault, inchworm, walk on their tentacles…
Medusae – swim, use water currents
Classification Class Hydrozoa
Most variable class Class Scyphozoa
True jellyfish Class Cubozoa
Cube jellyfishes Class Anthozoa
Largest class
Class Hydrozoa Mostly marine, but only class with
freshwater members! Most display alternation of
generations, but polyps are dominant form
Cnidocytes – only in epidermis Gametes released outside, from
epidermis Medusae have a ‘velum’ (shelf-
like lip), used for jet propulsion
Hydra
Freshwater
Polyps only, no medusae
Gonozooid(reproductive
zooid)
Gastrozooid(feeding zooid)
Obelia
Portugese Man-o-War, Physalia
Colony of polyps…
Cannot swim (floats)
Cnidocytes are lethal to small vertebrates and dangerous to humans
Class Scyphozoa “True Jellyfish” – medusa dominant body form
Cnidocytes in the epi + gastrodermis
Gametes released into gastroderm, then out of mouth
Medusae lack a velum
Moon Jellies, Aurelia
Stinging Nettle, Mastigias
Lions Mane, Cyanea
Record bell was 7 feet across, 120 ft. tentacles!
Class CubozoaMedusae are cuboidal
Polyps are reduced or absent
Tentacles hang from corners
Ex. Sea Wasp (type of Box Jellyfish)
Class AnthozoaPolyps only, no medusae
Gastrovascular cavity is divided into sections, with mesentaries
Sexual and asexual reproduction
Sea anenomes, corals, sea fans
Sea Anemones
Corals
Sea Fans