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Echinoderms. Ben Stevens, Sarah Leichty , Hannah Tamminga. Introduction to Types of Echinoderms. Have endoskeleton Have water-vascular system : network of water-filled canals with thousands of tube feet connected to it
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Echinoderms Ben Stevens, Sarah Leichty, Hannah Tamminga
Have endoskeleton • Have water-vascular system : network of water-filled canals with thousands of tube feet connected to it • Skeleton is made of calcium carbonate instead of chitin, which is stronger Compared to Arthropoda
All marine • Known as “spiny-skinned” animals • Endoskeleton (known as the test) is made of calcium plates with protruding spines • Undergo metamorphosis from bilateral, free-swimming larva to adult Unique Characteristics
Larval stage known as dipleurula or bipinnaria • Adults have pentaradial ( 5 part) symmetry • Lack segmentation • Coelomate • Breathe through skin gills as adults • Capable of extensive regeneration 1 5 2 4 3
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 • Tube feet on the underside of arms help in moving & feeding • One-way digestive system consists of mouth with oral spines, gut, & anus • Separate sexes • Reproduce sexually & asexually
water-filled tubes ending in numerous finger-like projections (tube feet) that stick out through the skin • tube feet on the end of the suckers are used for movement. • works on water pressure, creating a network of tube feet that look like hundreds of tiny, hydraulically operated legs Water-Vascular System
Shell made mainly of calcium carbonate, which is covered by skin • Skin contains: • cells for support and maintenance of the skeleton, • pigment cells • cells to detect motion on the animal's surface, • sometimes gland cells which secrete sticky fluids or toxins Tissue Types
reach highest diversity in marine reef environments but are also widespread on shallow shores • burrowing of sand dollars and sea cucumbers removes nutrients from the sea floor • Their digging activities increases the depth to which oxygen can seep and allows more complex ecology to develop • starfish and brittle stars prevent the growth of algal mats on coral reefs, which would get in the way of filter-feeding organisms Ecological Niche
some sea urchins can bore into solid rock and this bioerosion can destabilize rock faces and release nutrients into the ocean • have large population swings which can cause major consequences for ecosystems • capture about 100 million tons of carbon per year as calcium carbonate • important contributors in the global carbon cycle • diet of many organisms; many sea cucumbers provide a habitat for parasites, including crabs, worms and snails
Sexual organs are the gonads • located in the arms of the organism • exit the Echinoderm through a small opening near the anus • Sexual reproduction is more common • involves the fertilization of eggs with spermatozoa • Most of the classes start out as a bilaterally symmetrical larva • undergoes a radical transformation with a reorganization of the internal organs • Or a tiny radially symmetrical bud grows into the adult and the larval body is discarded Larvae Reproduction
Asexual reproduction is less common • Piece of parent is detatched • Regrows into new organism
http://vimeo.com/45154593 Digestive System - Starfish
Crinoidea • sit with arms outstretched parallel to the currents and filter feed • Asteroidea • predators or scavengers • Evert their stomachs (called cardiac stomachs), which secrete digestive enzymes on their prey • Some are also suspension feeders. • Brittle stars of the Ophiuroidea • predators, deposit feeders, scavengers, and suspension feeders, • feed by outstretching their arms to capture prey. • lack an intestine and anus, and therefore have an incomplete digestive system. Feeding
Echinoidea • suspension feeders, herbivores, detritivores, and predators • Many have a group of hard plates which retract and grasp like teeth, commonly called Aristotle's lantern. This allows most sea urchins to graze on algae. • Holothuroidea • suspension or deposit feeders. • may also eviserate their digestive and other organs in response to predation or seasonal events. Feeding cont.
Holothuriathomasi • Lives in the Caribbean and the Gulf of Mexico • anchor tightly in reef crevices, extending only the anterior portion of the body to feed on sand or algae-covered substrates • largest sea cucumber in the western Atlantic, but entire individuals are rarely seen and the species was not described until 1980 Tiger’s Tail
Evechinuschloroticus • found all around New Zealand in shallow waters around 12–14 meters deep • prefers areas with moderate wave action • mainly herbivorous , feeding on algae and encrusting substrate • fished commercially since 1986 in small quantities • has a reputation for having a bitter taste, this sea urchin is unable to reach a high price in export markets Kina
Coscinasteriascalamaria • largest seastar in southern Australia and New Zealand • found around low tide levels and below, under rocks and wandering over algae in pools • there can be any number of arms up to 14, but 11 is the norm • Armspread is up to 30 cm Eleven Armed Sea Star
http://www.mbgnet.net/salt/animals/echinod.htm • http://glencoe.mcgraw-hill.com/sites/dl/free/0328600529/303856/chap13.pdf • http://animalspeek.blogspot.com/2006/08/characteristics-of-echinoderms.html • http://deepseanews.com/2012/03/veins-of-water-the-evolution-of-the-echinoderm-water-vascular-system/ • http://www.geog.ubc.ca/biodiversity/efauna/EchinodermsofBC.html • http://w3.shorecrest.org/~Lisa_Peck/MarineBio/syllabus/ch7invertebrates/Invertwp/2007/tj/repro.html • http://www.mesa.edu.au/echinoderms/default.asp • http://biogeodb.stri.si.edu/bocas_database/search/species/1187
