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Justin Liu Antony Santiago Echinodermata Period 6 Click to Select a Topic Echinoderms Holothuroidea Excretion Classes Concentricycloidea Response Asteroidea Body Plans Movement Ophiuroidea Feeding and Digestion Reproduction Echinoidea Respiration Works Cited Crinoidea Circulation Home General Characteristics of Echinoderms • 6000 species • Pentamerous radial symmetry- the body can be • divided into five parts around a main axis Water vascular system- a hydraulic network of canals that run through the body, usually ending in a series of tube feet – The organism can control internal water pressure to extend/contract tube feet for locomotion, food collection, and respiration General Characteristics of Echinoderms cont. • Internal skeleton covered with spines and skin • – Consists of multitudes of ossicles (small calcareous plates) forming flexible joints Some species of sea stars actually extend their stomachs into their victims in order to digest them General Characteristics of Echinoderms cont. • A system of endoskeletal elements composed of a calcareous meshwork called the stereom • Construction of ambulacra (a radial area bearing tube feet) by the addition of new plates adjacent to the terminal, or ocular, plate that marks the ends of the radial canals. • A diffuse sub-epithelial nervous system Classes • There are six classes in the phylum Echinodermata. – Asteroidea – Ophiuroidea – Echinoidea – Crinoidea – Holothuroidea – Concentricycloidea Asteroidea (The Sea Stars) http://www.biodiversityexplorer.org/mm/echinoderms/asteroidea/index.htm Ophiuroidea (The Brittle Stars) http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata6.php http://www.eol.org/pages/2037 http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-6.php Echinoidea (The Sea Urchins and Sand Dollars) http://oceanlink.island.net/biodiversity/ask/echino.html http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-5.php Crinoidea (The Sea Lilies and Feather Stars) http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filoequinodermata-5.php http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-5.php Holothuroidea (Sea Cucumbers) http://www.portalsaofrancisco.com.br/alfa/filo-equinodermata/filo-equinodermata-6.php Concentricycloidea (Sea Daisies) http://www.mhhe.com/biosci/genbio/raven6b/grap hics/raven06b/other/raven06_47.pdf Body Plans • Bilateral Symmetry [in larvae]-left and right • • sides of an organism can be divided into mirror images of each other Radial Symmetry [in adults]-symmetrical arrangement of parts of an organism around a single main axis All echinoderms exhibit secondary radial symmetry, because they exhibit bilateral symmetry during larval development, but exhibit radial symmetry as adults. Feeding and Digestion • Echinoderms have a stomach and mouth area – Some echinoderms, such as sea cucumbers have a mouth on the bottom side of their body, and an anus on the front of their body. • In some echinoderms the tube feet are important sensory organs and assist in directing food into the mouth once the animal has captured it Feeding and Digestion Cont. • Some echinoderms are carnivorous and scavenge the ocean floor. • Others such as feather stars and sea cucumbers are mainly filter feeders, and catch food in ocean currents. • Certain species, such as the sea star, actually extend their stomach into an unwary victim to digest it. Respiration • Poorly developed respiratory system • Most echinoderms take in oxygen across the skin through small fingerlike extensions of the coelem (main body cavity) called papulae. • The papulae are covered with a thin layer of skin and protrude through the body wall to function as gills. Circulation • Echinoderms have a simple circulatory system that pumps water through its body. – echinoderms have an open circulatory system with cilia circulating the fluids through each arm. • The echinoderm’s coelom, or main body cavity, connects with a complicated system of tubes that helps to provide circulation Excretion • Amoeboid cells, which are foreign to the echinoderm, carry wastes out of the coelomic fluid. • Waste removal also occurs through small fingerlike extensions of the coelem called the papulae. • The process of excretion in echinoderms also makes use of the echinoderm’s water vascular system. Response • Have a poorly developed nervous system and lack a brain • Echinoderms have a light sensitive organ called a eyespot that can detect light and its general direction, which allows the echinoderm to move in response to light. • In some echinoderms their skin cells may be sensitive to certain chemicals given off by prey or predators Movement • All echinoderms possess an internal skeleton • In sea stars and brittle stars, the skeleton is made up of • small calcareous plates (ossicles) which form flexible joints that can be used for movement. An echinoderms tube feet work to enable movement – Canals of small muscular tubes (water vascular system) supplies water to the tube feet. – As tube feet press against a moving object, water is then withdrawn from the tube feet, which results in a suction effect. – When water returns to the canals the suction of the tube feet is released. – This type of movement is generally very slow. Reproduction • Echinoderms are classified as deuterostomes – In deuterostomes, the blastopore (the first opening that appears in the embryo) becomes the animal’s anus – Deuterostomes exhibit indeterminate development in which none of the daughter cell’s have a predetermined function and some daughter cells could even form a new organism. Reproduction cont. • Some echinoderms are diecious, meaning that there are separate female and male individuals. • The males and females discharge their sperm and eggs, respectively, into the water to be fertilized • A female can release one hundred million eggs at once Reproduction cont. • Echinoderms usually perform sexual reproduction, while some species perform asexual reproduction • Sexual reproduction involves the external fertilization of eggs by spermatozoa. • Asexual Reproduction usually involves the division of the body into two or more parts (fission) and the reproduction of missing body parts. Works Cited • Lambert, Phil. "Echinoderms of BC." UBC Department of Geography. Web. 20 Apr. 2010. • • • <http://www.geog.ubc.ca/biodiversity/efauna/Echin odermsofBC.html>. Echinoderms. Web. 20 Apr. 2010. <http://www.mcwdn.org/Animals/Starfish.html>. Wonders of the Sea: Echinoderms. Oceanside Meadows Innstitute for the Arts and Sciences. Web. 20 Apr. 2010. <http://www.oceaninn.com/guides/echino.htm>. Raven, Peter, George Johnson, Susan Singer, and Jonathan Losos. "Echinoderms." Biology. Sixth ed. McGraw-Hill Companies, 2001. 933-44. Print. Thank You