Phylum Cnidaria

Phylum Cnidaria: Diagnostic Features hydra, jellyfish, sea anemones, and corals fresh water & marine polymorphic (polyp & medusa forms) benthic & planktonic metazoans; tissue grade; diploblastic radiate predaceous

Cnidocytes- stinging cells with nematocysts

Histology epidermis- epithelial muscle cells contain contractile fibers gastrodermis- nutritive cells; flagellated; phagocytic mesoglea- secreted, gelatinous layer between epidermis and the gastrodermis

Physiology nervous system: "nerve net" respiration/excretion: diffusion/ammonia reproduction: budding; sexual reproduction in medusae; planula larvae

Classification Class Hydrozoa Class Scyphozoa Class Anthozoa

Class Hydrozoa (hydroids) diversity- 2700 species Obelia, Gonionemus, and Hydra Craspedacusta; found in Oklahoma; contains symbiotic algae Physalia- Portuguese Man-O-War; colonial pelagic hydrozoan; pneumatophores

Portuguese Man-O-War

Siphonophore

Obelia: a colonial hydrozoan

Obelia colony

Craspedacusta

Class Scyphozoa (true jellyfish) diversity- 6000 spp. most marine example: Aurelia

Aurelia life cycle

Class Anthozoa (anemones & corals) polyp form only all marine endosymbiotic algae

Coral Polyps

Sea Fan

Organ Pipe Coral

Sea Anemone

What is a coral reef? most diverse marine ecosystems on earth 200 million years in existence growth ~ 1.3cm per year calcium carbonate (CaCO3) zooxanthellae (endosymbiotic algae)

Where are the coral reefs? Coral reefs require clean, clear water that ranges in temperature from 24-30 OC.

Why does the coral reef need protection? visitors are destroying the reef touching, standing, or anchoring boat propellers oil

Why does the coral reef need protection? nutrient enrichment of coastal waters septic tank leakage wastewater outfall shallow injection wells fertilizers- nitrogen and phosphorus

Phylum Ctenophora “Comb Jellies”