Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Echinoderms All Materials © Cmassengale Phylum Echinodermata Characteristics All marine Known as spiny-skinned animals Endoskeleton known as the test is made of calcium plates or ossicles with protruding spines Includes sea stars, brittle stars, sand dollars, sea urchins, & sea cucumbers Undergo metamorphosis from bilateral, free-swimming larva to sessile or sedentary adult Larval stage known as dipleurula or bipinnaria Adults have pentaradial ( 5 part) symmetry Lack segmentation or metamerism Coelomate Breathe through skin gills as adults Capable of extensive regeneration Bipinnaria Larva Ventral (lower) surface called the oral surface & where mouth is located Dorsal (upper) surface known as aboral surface & where anus is located Have a nervous system but no head or brain in adults No circulatory, respiratory, or excretory systems Have a network of water-filled canals called the water vascular system to help move & feed Tube feet on the underside of arms help in moving & feeding One-way digestive system consists of mouth with oral spines, gut, & anus Deuterostomes (blastopore becomes the anus) Separate sexes Reproduce sexually & asexually Includes 5 classes: * Crinoidea - sea lilies & feather stars * Asteriodea - starfish * Ophiuroidea - basket stars & brittle stars * Echinoidea - sea urchins & sand dollars * Holothuroidea - sea cucumbers Class Crinoidea Characteristics Sessile Sea lilies & feather stars FEATHER STAR SEA LILY Have a long stalk with branching arms that attach them to rocks & the ocean bottom Can detach & move around Mouth & anus on upper surface May have 5 to 200 arms with sticky tube feet to help capture food (filter feeders) & take in oxygen Common in areas with strong currents & usually nocturnal feeders Class Asteroidea Characteristics Usually sedentary along shorelines Starfish or sea stars Come in a variety of colors Prey on bivalve mollusks such as clams & oysters Starfish Feeding on Clam Have 5 arms that can be regenerated Arms project from the central disk Mouth on oral surface (underside) STARFISH Class Ophiuroidea Characteristics Largest class of echinoderms Includes basket stars & brittle stars BASKET STAR Live on the ocean bottom beneath stones, in crevices, or in holes Have long, narrow arms resembling a tangle of snakes Arms readily break off & regenerate Move quicker than starfish Feed by raking in food with arms or trapping it with its tube feet BRITTLE STAR Class Echinoidea Characteristics Includes sea urchins & sand dollars SEA URCHIN SAND DOLLAR Internal organs enclosed by endoskeleton or test made of fused skeletal plates Body shaped like a sphere (sea urchin) or a flattened disk (sand dollar) Lack arms Bodies covered with movable spines Have a jawlike, crushing structure called Aristotle's lantern to grind food Use tube feet to move Sea Urchins: * Spherical shape * Live on ocean bottom * Scrape algae to feed * Long, barbed spines make venom for protection Sand Dollars: * Flattened body * Live in sand along coastlines * Shallow burrowers * Have short spines Class Holothuroidea Characteristics Includes sea cucumber SEA CUCUMBER Lack arms Shaped like a pickle or cucumber Live on ocean bottoms hiding in caves during the day Have a soft body with a tough, leathery outer skin Five rows of tube feet run lengthwise on the aboral (top) surface of the body Have a fringe of tentacles (modified tube feet) surrounding the mouth to sweep in food & water Tentacles have sticky ends to collect plankton Show bilateral symmetry Can eject parts of their internal organs (evisceration) to scare predators; regenerate these structures in days Structure & Function of Starfish Body Plan Range in size from 1 centimeter to 1 meter Mouth located on oral surface (underside) Have an endoskeleton made of calcium plates Sharp, protective spines made of calcium plates called ossicles found under the skin on the aboral (top) surface ABORAL SURFACE Have pedicellariae or tiny, forcep-like structures surrounding their spines to help clean the body surface Water Vascular System Network of canals creating hydrostatic pressure to help the starfish move WATER VASCULAR SYSTEM Water enters through sieve plate or madreporite on aboral surface into a short, straight stone canal Stone canal connects to a circular canal around the mouth called the ring canal Five radial canals extend down each arm & are connected to the ring canal Radial canals carry water to hundreds of paired tube feet TUBE FEET Bulb-like sacs or ampulla on the upper end of each tube foot contract & create suction to help move, attach, or open bivalves Rows of tube feet on oral surface (underside) are found in ambulcaral grooves under each arm Tube Feet in Ambulcaral Grooves Feeding & Digestion Tube feet attach to bivalve mollusk shells & create suction to pull valves apart slightly Starfish everts (turns inside out) its stomach through its mouth & inserts it into prey Stomach secretes enzymes to partially digest bivalve then stomach withdrawn & digestion completed inside starfish Other Body Systems No circulatory, excretory, or respiratory systems Coelomic fluid bathes organs & distributes food & oxygen Gas exchange occurs through skin gills & diffusion into the tube feet No head or brain Have a nerve ring surrounding the mouth that branch into nerve cords down each arm Eyespots on the tips of each arm detect light Tube feet respond to touch Reproduction Separate sexes Two gonads (ovaries or testes) in each arm produce eggs or sperm Have external fertilization Females produce up to 200,000,000 eggs per season Fertilized eggs hatch into bipinnaria larva which settles to the bottom after 2 years & changes into adult Asexually reproduce by regenerating arms