Phylum Cnidaria jellyfish, hydras, sea anemones, coraljellyfish, hydras, sea anemones, coral

Cnidaria have cnidocytes (stinging cells) which contain a nematocyst (harpoon-like structure) for stinging and paralyzing prey – located on tentacleshave cnidocytes (stinging cells) which contain a nematocyst (harpoon-like structure) for stinging and paralyzing prey – located on tentacles barbs coiled nematocyst discharged nematocyst

Tentacle Nematocyst “Trigger” Cuticle of prey Thread discharges Thread (coiled) Cnidocyte Thread

Cnidaria Radial SymmetryRadial Symmetry

made up of two tissue layers – endoderm and ectoderm separated by mesogleamade up of two tissue layers – endoderm and ectoderm separated by mesoglea Have two body forms: polyp and medusaHave two body forms: polyp and medusa Polyp Mouth/anus Body stalk Tentacle Gastrovascular cavity Endoderm Mesoglea Ectoderm Tentacle Mouth/anus Medusa

–Some cnidarians alternate between the 2 body forms: polyp – sessile, usually perform asexual reproductionpolyp – sessile, usually perform asexual reproduction medusa – free floating, usually perform sexual reproductionmedusa – free floating, usually perform sexual reproduction

Feeding polyp Reproductive polyp Medusa bud Medusa ASEXUAL REPRODUCTION (BUDDING) Portion of a colony of polyps 1 mm Key Haploid (n) Diploid (2n) Gonad SEXUAL REPRODUCTION MEIOSIS FERTILIZATION Egg Sperm Zygote Planula (larva) Developing polyp Mature polyp

Class Hydrozoa – hydras, Obelia, and Portuguese Man-of-WarClass Hydrozoa – hydras, Obelia, and Portuguese Man-of-War –usually alternate between polyp and medusa stages Portuguese Man-of-War

Class Scyphozoa – true jellyfish – have medusa as their primary body formClass Scyphozoa – true jellyfish – have medusa as their primary body form Jellies

Class Anthozoa – exists only as polyps, sea anemones and coralClass Anthozoa – exists only as polyps, sea anemones and coral Sea anemone (class Anthozoa)

Class Cubozoa – “box jellies”, sea wasps, marine, box-shaped medusae, potent venomClass Cubozoa – “box jellies”, sea wasps, marine, box-shaped medusae, potent venom Sea wasp (class Cubozoa)

Reproduction asexual reproduction by budding sexual reproduction by producing sperm in testes and eggs (ova) in ovaries fertilized egg becomes a larva which develops into an adult

Digestion food is taken in and wastes are expelled through the same opening – mouth digestion and circulation occur in the gastrovascular cavity

Polyp Mouth/anus Body stalk Tentacle Gastrovascular cavity Endoderm Mesoglea Ectoderm Tentacle Mouth/anus Medusa

Cnidaria have nerve tissue for coordinated movementhave nerve tissue for coordinated movement tissue level of organizationtissue level of organization