Tropical Marine Invertebrates CAS BI 569 Phylum Echinodermata by J. R. Finnerty Porifera Ctenophora Cnidaria Deuterostomia Ecdysozoa Lophotrochozoa Chordata Arthropoda Annelida Hemichordata Onychophora Mollusca Echinodermata *Nematoda *Platyhelminthes Acoelomorpha Calcispongia Silicispongiae PROTOSTOMIA Phylum Phylum Phylum CHORDATA ECHINODERMATA HEMICHORDATA Blastopore -> anus Radial / equal cleavage Coelom forms by enterocoely ! Protostome = blastopore contributes to the mouth blastopore mouth anus ! Deuterostome = blastopore becomes anus blastopore anus mouth Halocynthia, a tunicate (Urochordata) Coelom Formation Protostomes: Schizocoely Deuterostomes: Enterocoely Enterocoely in a sea star Axocoel (protocoel) Gives rise to small portion of water vascular system. Hydrocoel (mesocoel) Gives rise to water vascular system. Somatocoel (metacoel) Gives rise to lining of adult body cavity. Echinoderm Metamorphosis ECHINODERM FEATURES Water vascular system and tube feet Pentaradial symmetry Coelom formation by enterocoely Water Vascular System Tube Foot Tube Foot Locomotion ECHINODERM DIVERSITY Crinoidea Asteroidea Ophiuroidea Holothuroidea Echinoidea “sea lilies” “sea stars” “brittle stars” “sea cucumbers” “urchins, sand dollars” Group Form & Habit Habitat Ossicles Feeding Special Characteristics Crinoids 5-200 arms, stalked epifaunal Internal skeleton suspension mouth upward; mucous & Of each arm feeders secreting glands on sessile podia Ophiuroids usually 5 thin arms, epifaunal ossicles in arms deposit feeders act and appear like vertebrae Asteroids usually 5 stout arms epifaunal uniformly covered predators gonads extend into each except ambulacral arm grooves stomach extrusion Echinoids regular urchins epifaunal joined to form grazers Aristotle’s lantern- /radial; irregular rigid test or deposit special grazing jaw (sand dollars— feeders bilaterally symmetrical.) Holothuroids soft-bodied, worm- epifaunal microscopic & deposit feeders -branched respiratory like, elongated oral- or embedded in body structures (tree) aboral axis, lack infanual wall -evisceration arms; Echniodermata: Crinoidea mouth ambulacral groove with cilia tube feet coelom gonad ossicl e Echinodermata: Holothuroidea Oral & Aboral surfaces.