1 Echinoderms Odyssey Expeditions Jason Buchheim

2 Introduction Entirely marine Typically bottom dwellers Generally posses pentamerous radial symmetry at some point in life cycle (most can be divided into five parts around a central axis) Internal skeleton composed of calcareous ossicles (small plates)

3 Introduction Sexes are generally separate External fertilization Planktonic development Many have water vascular system (hydraulic system) for food collection and locomotion. –Motion accomplished by transmitting water pressure. Water vascular system in blue

4 Classes Class Asteroidea Class Ophiuroidea Class Echinoidea Class Holothuroidea Class Crinoidea Class Concentricycloidea

5 Class Asteroidea Sea stars 1,800 species Typically have five arms Regeneration capabilities (in some a new animal is formed) Mouth on bottom (centrally located) Anus on top NOAA

6 Class Asteroidea Carnivores, detritivores, opportunists, mud swallowers Some can invert stomachs out mouth to surround prey –Bivalve predators slide stomach between valves and feed on the organism while outside the body Organs distributed in arms Organs in arms

7 Class Asteroidea Two to four rows of podia (tube feet) extend down each arm from the mouth –Used for prey capture and locomotion Podia extended by hydraulic pressure –Pressure generated by contraction of bulblike ampulla In many, suckers are found on podia Arms can twist and bend allowing locomotion over varied terrain Podia

8 Class Ophiuroidea Brittle and Basket Stars Largest class (2,000 species) Mouth is centrally located on the underside of body Highly mobile Long thin arms Organs in central disk not arms Podia typically not responsible for locomotion Use arms to push and pull themselves along NOAA

9 Class Ophiuroidea Two distinct orders Order Ophiurae –Brittle Stars Order Euryalae –Basket Stars

10 Order Ophiurae Five arms generally heavily spined Calcareous plates (arm shields) on arm tops allow only lateral movement Arms break off easily Generally hide in crevices and under rocks during the day At night move into open to feed Feed on detritus and small animals NOAA

11 Order Euryalae Have five arms that continually divide into smaller branches Lack arm shields which enables full movement During day can be found curled into a ball clinging to gorgonians At night they stretch out their arms to filter out plankton that drifts over the reef Small spines and tube feet move food to mouth Jason Buchheim

12 Class Echinoidea Sea urchins, sand dollars and heart urchins 1,000 species Moveable spins cover theses animals No arms Circular or oval Globular or flattened Some display secondary bilateral symmetry Jason Buchheim

13 Class Echinoidea Ossicles are fused to create a solid structure called a test Two basic groups: –Regular Urchins (sea urchins) –Irregular Urchins (heart urchins, sand dollars, sea biscuit)

14 Regular Urchins Sea Urchins Generally globular in shape Covered with long moveable spines (some long and pointed some short and stubby) Anus on top Jason Buchheim

15 Regular Urchins Mouth centrally located on underside Scrape algae with their unique five teeth arrangement call Aristotle’s Lantern Important to the reef because of the algae control they provide. Mouth

16 Irregular Urchins Heart urchins, sand dollars, and sea biscuits Evolved to specialize in burrowing Small moveable spines cover the body and are used for burrowing Two orders: –Order Spatangoida (heart urchins) –Order Clypeasteroida (sand dollars and sea biscuits) USGS

17 Order Spatangoida Heart urchins Oval dome-like in shape Feed on organic materials in the substrate Mouth (lacks Aristotle’s Lantern) in front and anus in back Typically found buried in the substrate May be seen at night NOAA

18 Order Clypeasteroida Sand dollars and sea biscuits Flattened disk shape Mouth centrally located on the underside with Aristotle’s Lantern Anus found towards rear Live buried in the sand USGS

19 Class Holothuroidea Sea cucumbers Tubular in shape 1,000 species Mouth in front and anus in rear Most feed on organics found in the sand that they consume Some filter feed Odyssey Expeditions

20 Class Holothuroidea Tube feet cover the bottom surface If threatened can expel most of their guts Can regenerate these guts

21 Class Crinoidea Feather stars (Crinoids) Oldest echinoderms (living fossils) 600 species Five arms that fork to give ten or more Look like feathers Arms are sticky and sweep water for food particles Can regenerate arms Jason Buchheim

22 Class Crinoidea Can move short distances Some swim with arms Others walk on legs called cirri Jason Buchheim

23 Resources Barnes, Robert D. and Edward Ruppert. Invertebrate Zoology: Sixth Edition. Fort Worth: Saunders College Publishing, 1994 Humann, Paul and Ned Deloach. Reef Creature Identification: Florida Caribbean Bahamas. Florida: New World Publications, Inc., 2003 Kinsella, John, Drew Richardson and Bob Wohlers. Life on an Ocean Planet. California: Current Publishing Corp., 2006 Taylor, Walter K. and Robert L. Wallace. Invertebrate Zoology: A Laboratory Manual Sixth Edition. New Jersey: Prentice Hall, 2002