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Slide 1. Phylum Echinodermata. “Spiny Skin” Sea stars, sand dollars, sea urchins, feather stars, brittle stars, sea lilies, sea cucumbers and sea daisies. Slide 2. Major Characteristics of Echinoderms. Marine Invertebrates Endoskeleton Penta radial Symmetry Coelom
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Slide 1 Phylum Echinodermata “Spiny Skin” Sea stars, sand dollars, sea urchins, feather stars, brittle stars, sea lilies, sea cucumbers and sea daisies.
Slide 2 Major Characteristics of Echinoderms • Marine Invertebrates • Endoskeleton • Pentaradial Symmetry • Coelom • Water Vascular System • Deuterostome Development
Slide 3 Endoskeleton • A large number of calcium-rich plates, called ossicles make the body of the echinoderm. • The skin covers the ossicles, but may be worn away or have spines protruding through it. • Used for muscle attachment and protection.
Slide 4 Pentaradial Symmetry • 5 part radial symmetry as adults. • Larvae often have bilateral symmetry. • The number of arms may vary, but are most often in multiples of 5.
Slide 5 Coelom • A true coelom acts as a simple circulatory and respiratory system. • Skin gills are also useful for respiration and getting rid of waste. • Skin gills greatly increase the surface area for gas exchange with the sea water.
Slide 6 Water Vascular System • A system of water-filled canals connected to thousands of tube feet. • In many species, the tube feet extend out of the ossicles and have little suckers at the tip. • Useful for locomotion, feeding, gas exchange, and even excretion.
Slide 7 Water Vascular System:Path of water traveling through the water vascularsystem. • Water enters through the Madeporite or Sieve Plate. • Travels down the stone canal . . . • Around the ring canal . . . • Out the radial canals . . . • To the ampulla of the tube feet.
Slide 8 Tube Feet • Tube feet are a little like droppers. • When the ampulla squeeze, water exits the foot. • When the ampulla are full of water, there is suction at the bottom of the foot. Ampulla Tube Foot
Slide 9 Regeneration • Starfish do not have a head or brain. • The central disc contains a ring of nerves. If part of the central disc is present, regeneration can occur.
Slide 10 Errors in Regeneration • Sometimes, errors can occur. • A starfish may not regrow an arm, and have only 4 or fewer. • A starfish may regrow multiple arms and have 6 or more!
Slide 11 Diversity in Echinoderms:Class Ophiurodea • Brittle stars and sea baskets make up this largest class of echinoderms. • Some are predators, but most live on the ocean floor and feed on food from sediment or are filter feeders.
oceanexplorer.noaa.gov www.scubacentro.com
Slide 12 Diversity in Echinoderms:Class Crinoidea • Sea lilies and feather stars are the most ancient and primitive of the living echinoderms. • The mouth is on the upper instead of lower surface. • Most sea lilies and feather stars are sessile filter feeders.
www.childrensmuseum.org tackettproductions.com
Slide 13 Diversity in Echinoderms:Class Echinodea • Sea urchins and sand dollars do not have distinct arms, but do display pentaradial symmetry. • Sea urchin spines are used for protection, and may contain a venom that causes a severe burning sensation. • Sand dollars live in sandy coastal waters.
www.humboldt.edu www.users.zetnet.co.uk
Slide 14 Diversity in Echinoderms:Class Holothuroidea • Sea cucumbers have very small, unfused ossicles, so their body feels soft, with a tough, leathery exterior. • Their tube feet are modified into sticky tentacles that trap plankton. The sea cucumber draws the tentacles into the mouth to feed. • Sea cucumbers can eject sticky threads from it’s anus to trap potential attackers.
Slide 15 Diversity in Echinoderms:Class Asteroidea • Sea stars (a.k.a. starfish) are the most well-known. They are carnivores and often predators! • A crown-of-thorns can eat 65 feet of coral polyps in one hour! Over time it could destroy an entire reef ecosystem. • Sea stars have eyespots at the end of each arm to detect light and tiny tentacles to respond to touch. • Many sea stars have pinchers called pedicellarie which contain their own muscles and nerves and snap at anything that touches them! This prevents organisms from attaching to the surface.
Slide 16 Feeding in Sea Stars • Feed on mollusks, worms, and other slow-moving animals. • Tube feet grasp onto 2 halves of a clam shell and pulls until it opens. • Turns stomach inside out, and begins digesting the clam right in its shell! • Returns stomach in through mouth to finish digestion. • Solid waste exits through the mouth.
Slide 17 Reproduction in Sea Stars • Separate sexes, with 2 gonads in each arm. • External fertilization and development. • Regeneration can occur if part of the central disc is present.
Slide 18 Other Info You Should Know: • Oxygen is obtained and waste is excreted through the skin gills and diffusion across tube feet. • Nervous control: • Nerve ring and nerve cord coordinate nerve messages. • Tube feet respond to touch. • Eyespots at the end of each arm respond to light. • Small tentacles on each arm respond to touch.
Sea stars eat many mollusks, can destroy clam beds. Sea stars also eat coral, could destroy reef ecosystem. Beautiful - tourism Chemical signals for regeneration studied for human applications. Sea urchin fertilization is dependent on water quality - it’s a monitor! Slide 19 Ecological Importance ofEchinoderms
