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How do Echinoderms feed and digest? Crinoids Filter feed with oral side up and arms and pinnules outstretched. Food particles brought to mouth via cilia in ambulacral grooves. Mouth opens to short esophagus, to long intestine, to anus. How do Echinoderms feed and digest? Asteroids Most are predators and scavengers. Eversible portion of stomach (cardiac stomach) extruded onto or into prey. How do Echinoderms feed and digest? Asteroids Mouth ---> cardiac stomach ---> pyloric stomach ---> pyloric ducts ---> pyloric cecae ---> intestine ---> anus How do Echinoderms feed and digest? Ophiuroids Predators, scavengers, filter feeders, deposit feeders. Food collected and passed along podia and spines to mouth. Digestive system reduced with no anus. How do Echinoderms feed and digest? Echinoids Herbivores, suspension feeders, detritovores. Urchins have Aristotle’s lantern. Hard plates and muscles that control protraction of five teeth. Teeth scrape algae off rocks and take bites of macroalgae. Can excavate holes in rocks. How do Echinoderms feed and digest? Echinoids Digestive mouth system ---> esophagus out of Aristotle’s lantern ---> long intestines ---> rectum ---> anus. How do Echinoderms feed and digest? Holothuroids Suspension and deposit feeders. Extend mucus-covered buccal tentacles into water. Tentacles are pushed into mouth one at a time. Mouth ---> esophagus ---> long intestines ---> rectum ---> anus. How do Echinoderms feed and digest? Holothuroids - defense against predators Cuverian tubules -sticky tubes at base of respiratory tree. Entangle predators. Evisceration – discharge of all or part of the digestive organs Organs are regenerated later How do Echinoderms maintain homeostasis? Circulation Internal transport by coeloms, water vascular system, and hemal systems. Hemal system -array of canals and spaces enclosed within coelomic channels called perihemal sinuses. Parallels water vascular system. Probably helps distribute respiratory gases and nutrients. How do Echinoderms maintain homeostasis? Gas exchange Across podia and dermal gills (dermal branchia). Countercurrent exchange. How do Echinoderms maintain homeostasis? Gas exchange Ophiuroids have ten invaginations in the body wall called bursae. Water circulated by cilia. How do Echinoderms maintain homeostasis? Gas exchange Holothuroids have respiratory trees. Water is actively pumped by muscular hind end. Gases picked up by coelom and hemal system. How do Echinoderms maintain homeostasis? Osmoregulation Osmoconformers. Waste is usually ammonia lost across podia and dermal branchia. How do Echinoderms reproduce and develop? Asexual reproduction Most capable of regenerating lost parts. Holothuroids regenerate intestines and respiratory trees. Asteroids and ophiuroids regenerate lost arms and suckers. How do Echinoderms reproduce and develop? Sexual reproduction Most gonochoristic. Gonads housed in genital sinuses. In classes with multiple gonads, each has own gonopore in an interambulacral area. How do Echinoderms reproduce and develop? Sexual reproduction Free spawning with indirect development to brooding with direct development. How do Echinoderms reproduce and develop? Sexual reproduction Isolecithal egg with small amount of yolk. Radial holoblastic cleavage ---> coeloblastula ---> coelogastrula by invagination ---> blastopore becomes anus ---> coelom formation by enterocoely ---> embryo becomes bilaterally symmetrical and develops into a larva. Vitellaria of crinoid Bipinnaria and brachiolaria of seastars How do Echinoderms reproduce and develop? Sexual reproduction Isolecithal egg with small amount of yolk. Radial holoblastic cleavage ---> coeloblastula ---> coelogastrula by invagination ---> blastopore becomes anus ---> coelom formation by enterocoely ---> embryo becomes bilaterally symmetrical and develops into a larva. Ophiopluteus of brittle star Echinopluteus of urchin. Aricularia of sea cucumber