Lecture Exam I Cambrian radiation / phylogeny = 2 papers Systematics intro Protista: 10 phyla Animalia: Porifera, Cnidaria ~20 questions Short answer, essay, life cycle sketch

Phylum Cnidaria 3 Classes: – –Anthozoa – –Scyphozoa – –Hydrozoa

Characteristics: Diploblastic metazoan Ectoderm and endoderm separated by acellular mesoglea Nervous system: simple nerve net, neurons

Development Planula larvae ciliated, motile, gastrula larva

Radial symmetry Modified into biradial, quadradial, etc…

Saclike, partitioned, or branched w/ one opening = mouth and anus Gastrovascular cavity

Alternating life history forms: polyp and medusa

Polyp Radial symmetry Oral end = hypostome or manubrium in hydrozoans – –flat pedal disc in anthozoans Tentacles surround mouth

Polyp Gastrovascular cavity Circulation, digestion, distribution of nutrientsCirculation, digestion, distribution of nutrients Hydrozoans: coelenteron is single tubeHydrozoans: coelenteron is single tube Scyphozoans: four longitudinal mesenteriesScyphozoans: four longitudinal mesenteries Anthozoans: compartmentalized by mesenteriesAnthozoans: compartmentalized by mesenteries

Polyp: support Hydrostatic, water-filled coelenteron Hydrostatic, water-filled coelenteron Anthozoans - bits of sediment and shell fragments in column wall for support Anthozoans - bits of sediment and shell fragments in column wall for support Hydrozoans - flexible horny perisac (periderm) of chitin from epidermis Hydrozoans - flexible horny perisac (periderm) of chitin from epidermis

Polyp: movement Retractor muscles: longitudinal fibers along mesenteries Circular muscles: sphincters – –in tentacles and oral disc Most polyps sedentary or sessile Creep slowly w/ pedal disc musculature UI531GMRTM

Medusa All cnidaria except Anthozoa Bell-, dish- or umbrella-shaped Exumbrella: convex upper (aboral) surface Subumbrella: concave lower (oral) surface – –Mouth at center Free-floating, mouth down

Medusa External surface: epidermis Internal surface: gastrodermis Coelenteron central; extends to radial canals – –Usually four radial canals, tentacles, stomach divided by mesenteries into four gastric pouches

Stinging structures Nematocysts

Nematocysts: multiple types Generic nematocyst (all) – –Double-walled capsule w/ toxic mixture of phenols + proteins – –Spines or barbs for penetration, anchor in victim Spirocyst (Anthozoa) – –Spring-like mechanism – –Adhesive tubules wrap around and stick to victim Ptychocyst (tube anemones) – –Create capsule tubule

Feeding and digestion Tentacles capture prey, carry to mouth, ingest whole Extracellular digestion in coelenteron – –enzyme-producing cells

Reproduction and Development Hydrozoa Polyps = asexual budding

Reproduction and Development Hydrozoan Free-living hydromedusa Dioecious, release sperm or eggs

Reproduction and Development Scyphozoa Asexual reproduction: small polyp = scyphistoma Medusa from scyphistoma Immature medusa = ephyra Most species dioecious

Reproduction and Development Anthozoa Exclusively polyps Asexual reproduction Fission Pedal laceration: pedal disc spreads, anemone moves, leaves small fragments – – develop into adult

Class Hydrozoa Hydroids and hydromedusa

Hydrozoa Portuguese Man-of-war Physalia

Class Anthozoa Anemones, corals, sea pens Exclusively marine Octocorals Soft corals – – Gastraxonacea – – Helioporaceans – – Sea pens and sea pansies – – Protoalcyonaria – – Stoloniferans – – Telestaceans Sea pen

Class Anthozoa Anemones and true corals True sea anemones True corals (stony corals)

Class Anthozoa Black or thorny corals Ceranthids or tube anemones

Class Scyphozoa Jellyfish

Box jelly Chiropsalmus