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Animal Bio: Echinoderms

by: Isabel Notetaker

Animal Bio: Echinoderms BIOL 1112

Isabel Notetaker
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About this Document

These notes cover the various species of marine echinoderms (starfish, brittle stars, sea cucumbers, urchins, sea lilies).
Animal Biology
Cassandra D Pauling
Class Notes
animal, Biology, Marine, Echinodermata




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Popular in Biology (105, Biol for the Health Sciences)

This 5 page Class Notes was uploaded by Isabel Notetaker on Friday October 14, 2016. The Class Notes belongs to BIOL 1112 at University of Central Missouri taught by Cassandra D Pauling in Fall 2016. Since its upload, it has received 10 views. For similar materials see Animal Biology in Biology (105, Biol for the Health Sciences) at University of Central Missouri.

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Popular in Biology (105, Biol for the Health Sciences)


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Date Created: 10/14/16
Animal Bio-Unit 3 Notes Echinoderms- Chapter 22 Phylum Echinodermata o “prickly skin” o All marine o Starfish, brittle stars, sea cucumbers, urchins, sea lilies o Deuterosomes • Characteristics o Bottom feeders o None are parasitic, but few are commensals § Many animals live on then o Because they are spiky, they are usually not prey items § Contrary to this, otters eat urchins to keep the populations in check § Some will eat other echinoderms o Not segmented body, but shows pentaradial § Larvae are bilaterally symmetrical o No nervous system § Rely on tactile and chemoreceptors o All echinoderms have: § Endoskeleton has ossicles (plates) with spines or have spicules in dermis § Unique wwater-vascular0system • Series of canals extend as tube feet § Reduced blood-vascular system § Papulae (dermal bronchiae, skin gills) § Tube Feet- tentacle-like suckers • Enable animals ot move § Autonomy (can remove injured arm and regrow a new one)and regeneration • Can sometimes grow a new starfish from “cast off arm” § Separate sexes § No excretory organs • Classes of Echinoderms o Class Asteroidea-sea stars or starfish o Class Ophiuroidea-brittle stars o Class Echinoidea-Sea Urchins, Sand Dollars o Class Holothuroidea-sea cucumbers o Class Crinoidea-Sea lilies and feather stars • Class Asteroidea o Sea Stars o Commonly found on hard, rocky surfaces and sandy substraights o Some particle feeders, some predators o Starfish form and function § Central disk with 5 arms § Epidermis ciliated and pigmented § Mouth is found on the oral surface the opposite side of the animal being referred to as the aboral surface § Ambulacra-(grooves) contains a large radial nerve that runs form the mouth to the tip • Bordered by tube feet (podia) which are boardered by protective, moveable spines. Podia are part of the water-vascular system and are for locomotion, clinging, handling food, and respiration § Madreporite-on aboral side, calcareous sieve leading to the water- vascular system § Pedicellariae-around the base of spines (tiny jaws) • Keeps body surface clean, protect palpulae, sometimes aid in food capture § Papulae-dermal branchiae or skin gills • Soft, delicate projections of coelomic cavity § Endoskeleton • Ossicles (calcareous plates) found together with connective tissue o Made of catch collagen § Can change from liquid to solid very quickly • Allows them to hold various postures without muscular effort • Spines and tubercles that form the spiny surface project form ossicles • Muscles are used to move arms and partially close ambulacral grooves § Water-Vascular System • Coelomic compartment unique to echinoderms o Canals specialized tube feet, and dermal ossicles form a hydraulic system used for: § Locomotion § Collecting food § Respiration § Excretion • The water vascular system opens to the outside via small pores in the madreporite on the aboral surface • The madreporite connects to a ring canal and from this ting canal, radial canals extend down the ambulacral groove of each arm • The water vascular system uses hydraulic pressure to extend, move, and contract the tube feet enabling the starfish to move and feed o Feeding and Digestion § Mouth opens into a two-part stomach in the central disk of the animal § Upper: pyloric stomach connects to the pyloric ceca § Lower: Cardiac Stomach can be everted during feeding • Important in sea stars’ ability to consume certain prey § Pyloric Ceca-digestive glands in each arm • Digesiton mostly Extracellular § Most sea stars feed on molluscs, crustaceans, annelids, other invertebrets and other echinoderms o Regeneration § Some use regeneration as asexual reproduction, rather than putting their gametes into the open water § Rather than using energy to try to heal an injured appendage, the arms can be severed and could possibly grow another star fish. • Class Ophiruida o Brittle stars are different from starfish § Jointed arms, allows for movement much quicker than star fish § Slender, sharply set off from central disk § No pedicellariae or papulae, no tube feet, no suckers § Ambulacral grooves closed and covered with ossicles § Madreporite located on oral surface § mouth surrounded by five movable plates that act as jaws § Leathery skin with dermal plates and spines § Lack intestines and anus • Waste exits via the mouth • Eats small particles • Some carnivorous § Capable or regeneration and autonomy o Basket Stars § Filter feeders § No tube feet, also has closed canals § Oral and aboral side • Used for incurrent and outcurrent • Class Echinoidea o Sea Urchins, sand dollars, and heart urchins o Compact body surrounded by a calcareous shell (test) § Test-formed by dermal ossicles that are closely fitting plates, appear to be sutured together, visible seams § Compact skeleton of 10 double rows of plates that bear movable, stiff, long spines o Wide distribution in all seas o Aristotle’s Lantern § Not in heart Urchins § Complex chewing mechanism and coiled digestive system § Teeth are attached • Retractor muscles draw teeth and lantern up into test • Protractor muscles push the lantern down and expose the teeth • Class Holothuroidea o Sea cucumbers § Very elongated along the oral-aboral axis and have an array of oral tentacles (modified tube feet) around the mouth § Sluggish and slow § Feed on deposits or are filter feeders § Leathery body wall with tiny ossicles embedded § Most have well-developed tube feet • Typically called a Sole • If tube feet are present in dorsal areas they are usually without suckers or modified sensory papillae § Defence mechanism • When irritated they will cast out part of their viscera-poisonous • Class Crinoidea o Sea lilies and feather stars § Extensive fossil records o Feathery appearance, resulted from the branching of their five arms to produce many more o Sessile o Occur commonly in deep water but can be found in shallow regions o Calix (body disk), covered in tegmen (leathery skin), which contains calcareous plates o Crown- calix and arms o Stalk-on cessile forms § May bear Cirri o Filter feed o No spines, madreporite, or pedicellariae in this class Phylum Hemichordata • Worm-like organisms that live on the bottom of the ocean and are usually found in shallow waters • Gill slits and a rudimentary notochors • NOT homologus to notochord in chordates, which have stomochords • Two classes: o Enteropneusta (acorn worms) o Pterobranchia • Mucis-covered body that is divided into 3 regions o Proboscis (probes surrounding, collects food, excavated burrows) o Collar (food directed to the groove at the edge o Trunk (rest of the body • Class Enteropnuesta o Acorn worms o Live in benthos • Class Pterobranchia o Small, colonial animals o Only 3 genera known


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