Lecture 7: Phylum Cnidaria, Part 2 Invertebrate Zoology Lecture 7: Phylum Cnidaria, Part 2
Class Hydrozoa Siphonophore Photo: K. Raskoff / Monterey Peninsula College
Class Hydrozoa Order Hydroidea: the hydroids Polyp form often colonial, branched (Obelia) Includes feeding and reproductive polyps Coenosarc: common gastrovascular cavity
Class Hydrozoa Order Hydroidea: life cycle (Obelia sp.)
Planula larvae Some solid, others with g.v. cavity Move via cilia
Class Hydrozoa Order Siphonophora Two medusa types Swimming Sexual Reproduction Polyps: feeding, defense, asexual reproduction Predators! Gas-filled float Many variations!
Class Hydrozoa Order Siphonophora Cormidium “colony within a colony” Detachable
Class Hydrozoa Order Chondrophora (Velella velella, by-the- wind sailors): Free-floating polyp Secondary polyps (feeding, reproduction) Tiny, free-living medusae
Class Hydrozoa Order Trachylina: life cycle No true polyp stage Planula develops into medusa
Class Hydrozoa Order Hydrocorallina: hydrocoral, fire coral Not a “true” coral! (True coral = C. Anthozoa) Calcareous skeleton Some with symbiotic zooxanthellae Polyps within chambers Reduced medusa stage Why called “fire” coral?
Class Scyphozoa Semaeostomae (most jellies) Stauromedusae Key predators (impact?) Stauromedusae Sessile medusa or polyp? Develop from planula larva
Class Scyphozoa Life cycle, Semaeostomae (Aurelia) Key: strobilation of polyp ephyra medusa
Class Scyphozoa Pelagia Note trailing mouth lobes
Class Scyphozoa Life cycle, Pelagia No polyp stage: planula ephyra medusa
Class Cubozoa: box jellies Polyp medusae via direct metamorphosis Chironex: deadliest toxin known www.zoologie-online.de/.../Cubozoa/cubozoa.html
Class Anthozoa Anemones Coral Sea pansies Gorgonians Etc…
Class Anthozoa Generalized life history: no medusae Asexual reproduction also important
Class Anthozoa: Subclass Hexacorallia Order Actiniaria: solitary anemones
Class Anthozoa: Subclass Hexacorallia Order Corallomorpha Anemone-like, but with clubbed tentacles Clonal form shown; clone wars occur!
Class Anthozoa: Subclass Hexacorallia Order Scleractina: stony (“true”) corals Deposit CaCO3 skeletons Contain mutualistic zooxanthellae Some are reef builders Clubbed tentacles; polyps open at night…
Class Anthozoa: Subclass Hexacorallia Order Scleractina: stony (“true”) corals Gastrovascular cavity connects polyps Mutualistic zooxanthellae within gastrodermis = acontia Mesentery =
Class Anthozoa: Subclass Hexacorallia Order Scleractinia: stony (“true”) corals Initial colony: from planula larva produced sexually (VIDEO!) Colony growth: asexual division Fragmentation “new” colony
Class Anthozoa: Subclass Ceriantipatharia Order Ceriantharia: tube anemones Double whorl of tentacles Build sand tubes; capable of burrowing
Class Anthozoa: Subclass Octocorallia Features of subclass Eight-tentacled, pinnate polyps Eight complete mesenteries
Class Anthozoa: Subclass Octocorallia Order Gorgonacea: sea whips, sea fans skeleton of gornonin (protein), and/or calcareous spicules often highly branched in one plane Oriented perpendicular to prevailing current
Class Anthozoa: Subclass Octocorallia Order Alcyonacea: soft corals fleshy, sometimes tree-like pump water throughout the colony Scubatravel.com www.freeinfosociety.com
Class Anthozoa: Subclass Octocorallia Order Pennatulacea: sea pens, sea pansies Main body = polyp; has secondary, lateral polyps Gastrozooids (feeding) Siphonozooids (water flow) Calcareous spicules provide structure © Alvaro E. Migotto
Class Anthozoa: Subclass Octocorallia Order Stolonifera: organ pipe coral Calcareous "spicules" provide structure Polyps within tubes or on stalks