pincers Echinoderms Echinoderms are are found in all the found in all the oceans oceans of the world of the world What is an echinoderm What is an echinoderm brPage 2br SKIN all have a hard SKIN all have a hard spiny spiny or bumpy or bumpy endosk ID: 81305
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Echinoderms Echinoderms move move by means of hundreds of by means of hundreds of hydraulic hydraulic , , suction suction - - cup cup - - tipped tipped appendages and appendages and have skin covered with tiny, have skin covered with tiny, jawlike jawlike pincers. pincers. Echinoderms Echinoderms are are found in all the found in all the oceans oceans of the world. of the world. What is an echinoderm? What is an echinoderm? SKIN: all have a hard, SKIN: all have a hard, spiny spiny , or bumpy , or bumpy endoskeleton endoskeleton covered by a thin covered by a thin epidermis epidermis . . Echinoderms have endoskeletons Echinoderms have endoskeletons Endoskeleton of all echinoderms is made Endoskeleton of all echinoderms is made primarily of primarily of calcium carbonate calcium carbonate , the compound , the compound that makes up that makes up limestone limestone . . Some Some spines spines have become have become modified modified into into pincerlike pincerlike appendages called appendages called pedicellariae pedicellariae (PEH (PEH dih dih sih sih LAHR LAHR ee ee ay). ay). Echinoderms have endoskeletons Echinoderms have endoskeletons An echinoderm uses An echinoderm uses its its jawlike jawlike pedicellariae pedicellariae for for protection protection and for and for cleaning cleaning the surface the surface of its body. of its body. Pedicellariae Echinoderms have radial symmetry Echinoderms have radial symmetry Radial Radial symmetry is an symmetry is an advantage advantage to animals to animals that are that are stationary stationary or or move slowly move slowly . . Radial Radial symmetry symmetry enables enables these animals these animals to to sense sense potential potential food food , , predators predators , and other , and other aspects of their aspects of their environment from environment from all all directions directions . . The water vascular system The water vascular system The The water vascular system water vascular system is a is a hydraulic hydraulic system that operates under system that operates under water pressure water pressure . . Water Water enters and leaves the water vascular enters and leaves the water vascular system of a sea star through the system of a sea star through the madreporite madreporite ( ( mah mah druh druh POHR POHR ite ite ), ), a a sievelike sievelike , disk , disk - - shaped shaped opening opening on the on the upper surface upper surface of the of the echinoderms body. echinoderms body. The water vascular system The water vascular system The The underside underside of a sea star has of a sea star has tube feet tube feet that that run along a groove on the underside of each run along a groove on the underside of each ray. ray. The water vascular system The water vascular system Tube feet Tube feet are are hollow hollow , , thin thin - - walled tubes walled tubes that that end in a end in a suction cup suction cup . . The round, The round, muscular muscular structure called the structure called the ampulla ampulla (AM pew (AM pew lah lah ) ) works something like works something like the the bulb of a dropper bulb of a dropper . . Each tube foot works Each tube foot works independently independently of the of the others, and the animal moves along slowly others, and the animal moves along slowly by by alternately alternately pushing out and pulling in its pushing out and pulling in its tube feet. tube feet. Section 29.1 Summary Section 29.1 Summary pages 763 pages 763 - - 769 769 The water vascular system The water vascular system Tube feet Tube feet also also function function in in gas exchange gas exchange and and excretion excretion . . Echinoderms have varied nutrition Echinoderms have varied nutrition All echinoderms have a All echinoderms have a mouth mouth , , stomach stomach , and , and intestines intestines , but their methods of obtaining food , but their methods of obtaining food vary. vary. Sea stars Sea stars are are carnivorous carnivorous and prey on and prey on worms worms or on or on mollusks mollusks such as clams. such as clams. Echinoderms have varied nutrition Echinoderms have varied nutrition Most Most sea urchins sea urchins are are herbivores herbivores and graze on and graze on algae algae . . Brittle stars, Brittle stars, sea lilies sea lilies , and , and sea cucumbers sea cucumbers feed on feed on dead dead and and decaying decaying matter that drifts matter that drifts down to the ocean floor. down to the ocean floor. Echinoderms have a simple nervous system Echinoderms have a simple nervous system Echinoderms Echinoderms have no have no head head or or brain brain , but they do , but they do have a have a central central nerve ring nerve ring that that surrounds the surrounds the mouth mouth . Ring canal Echinoderms have a simple nervous system Echinoderms have a simple nervous system Nerves Nerves extend from the extend from the nerve ring nerve ring down each down each ray ray . . Echinoderms have Echinoderms have cells cells that detect that detect light light and and touch touch , but most do not have , but most do not have sensory organs sensory organs . . A sensory organ known as an A sensory organ known as an eyespot eyespot and and consisting of a cluster of consisting of a cluster of light light - - detecting cells detecting cells is is located at the located at the tip tip of each of each arm arm , on the , on the underside underside . . Echinoderms have a simple nervous system Echinoderms have a simple nervous system Eyespots Eyespots enable sea stars to detect the enable sea stars to detect the intensity intensity of of light light . . Sea stars also have Sea stars also have chemical receptors chemical receptors on on their their tube feet tube feet . . Echinoderms are deuterostomes Echinoderms are deuterostomes Echinoderms are Echinoderms are deuterostomes deuterostomes ; a broad ; a broad classification of classification of triploblastic triploblastic animals that tend animals that tend to to share share certain certain embryological traits embryological traits . . This pattern of development indicates a close This pattern of development indicates a close relationship relationship to to chordates chordates , which are also , which are also deuterostomes deuterostomes . . Approximately Approximately 6000 6000 species of echinoderms species of echinoderms exist today. exist today. About About one one - - fourth fourth of of these species are these species are in the class in the class Asteroidea Asteroidea (AS (AS tuh tuh ROY ROY dee dee uh) uh) , to , to which the which the sea stars sea stars belong. belong. Diversity of Echinoderms Diversity of Echinoderms Section 29.1 Summary Section 29.1 Summary pages 763 pages 763 - - 769 769 Diversity of Echinoderms Diversity of Echinoderms The five other classes of living The five other classes of living echinodems echinodems are: are:1.) Ophiuroidea (OH fee uh ROY deeuh) the brittle stars 2.) Echinoidea (eh kihnOY deeuh) , the sea urchins & sand dollars . 3.) 3.) Holothuroidea Holothuroidea (HOH (HOH loh loh thuh thuh ROY ROY dee dee uh) uh) , the , the sea cucumbers sea cucumbers 4.) 4.) Crinoidea Crinoidea (cry NOY (cry NOY dee dee uh) uh) , the , the sea lilies sea lilies & & feather stars feather stars 5. 5. Concentricycloidea Concentricycloidea ( ( kon kon sen sen tri tri sy sy CLOY CLOY dee dee uh) uh) , , the the sea daisies sea daisies . . Diversity of Echinoderms Diversity of Echinoderms