http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/Content/sea-star-pair-75

1. Echinodermata Riley Galton Julia Heunis David Lin http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/Content/sea-star-pair-758303-sw.jpg

2. Riley Galton Echinoderm Classes Asteroidea – Sea Stars: • Multiple arms radiating from central disk • Tube feet on bottom http://photography.nationalgeographic.com/staticfiles/ Ophiuroidea – Brittle Stars: • Distinct central disk with snake like arms • Tube feet lack suckers http://environment.nationalgeographic.com/staticfiles/

3. Riley Galton Echinoderm Classes Echinoidea – Sea Urchins and Sand Dollars: • No arms, but 5 rows of tube feet • Have muscles that can move • spines www.emiliogrossi.com/images/Photographyiles/ Crinoidea – Feather Stars and Sea Lilies • Flexible arms used in suspension feeding • Haven’t changed in 500 million years http://environment.nationalgeographic.com/staticfiles/ http://lh6.ggpht.com http://image44.webshots.com

4. Riley Galton Echinoderm Classes Holothuroidea – Sea Cucumbers • Reduced endoskeleton • Five rows of tube feet http://www.sfu.ca/~fankbone/v/xyloplax.jpg Concentricycloidea – Sea Daisies • Only two known species • Disk shaped, less than 1cm in diameter http://blog.case.edu/case-news/2008/03/06/seacucumber.jpg

5. Riley Galton Echinoderm Sensory Structures • Eyespots on the ends of ambulacra are sensitive to light • Pedicellariae(jaw like skeletal structures used to keep organisms from settling on skin),tube feet, and spines are sensitive to touch http://www.ucmp.berkeley.edu/echinodermata/echinomm.html

6. Riley Galton Echinoderm Reproduction http://www.biolbull.org/content/vol204/issue3/images/medium/coverfig.gif Sexual: • Eggs and sperm are released into the water where they are fertilized • Larvae are planktonic • Internal fertilization has been observed in certain species of sea stars, brittle stars, and sea cucumbers Asexual: • Echinoderms can regenerate body parts and organs • Asexual reproduction can occur (though not by will) if the echinoderm is torn with enough of the body on each part http://www.oceaninn.com/guides/echino.htm http://www.starfish.ch/Fotos/echinoderms

7. Julia Heunis Body Cavity (Coelom) • PRESENT! • Coelom = A fluid-filled cavity between body wall and gut; lined by mesoderm • Two parts: Perivisceral coelom – large, fluid-filled cavity where major organs, digestive tube and sex organs, are suspended Water Vascular System - network of hydraulic canals unique to echinoderms that branches into extensions (tube feet) which function in locomotion, feeding and gas exchange http://www.colin.edu/science/awashington/syllabi/General%20Zoology%20Terminology.htm http://biology.kenyon.edu/courses/biol112/Biol112WebPage/Syllabus/Topics/Week%207/Resources/coelom.GIF http://www.britannica.com/EBchecked/topic/452108/perivisceral-coelom http://www.und.nodak.edu/instruct/jvaughan/b151/VOCAB_vertebrates.html

8. Julia Heunis Body Symmetry http://tbn2.google.com/images?q=tbn:KrJSbsj0l4ImqM:http://photos.tobinhosting.com/d/117553-2/sea%2Burchins.jpg • evolved from animals with bilateral symmetry • adult echinoderms possess radial symmetry • All echinoderms exhibit fivefold radial symmetry in portions of their body at some stage of life (5 parts around central axis), even if they have secondary bilateral symmetry • For the most part… LARVAE ~ bilateral ADULTS ~ radial http://en.wikipedia.org/wiki/Echinoderm

9. Julia Heunis Excretory System • NO true excretory system! • Main opening of a sponge used only to EXPEL WASTE • Anus leads directly from stomach/digestive tract • Anus = top mouth = bottom universe-review.ca

10. Olivia Heunis http://universe-review.ca/I10-82-starfish.jpg

11. Julia Heunis Skeletal TypeEchinodermata: “Spiny Skinned” • DO NOT possess an exoskeleton • a thin outermost skin covers a mesodermal endoskeleton made of tiny calcified plates and spines - forms rigid support contained within tissues of the organism • Skeleton composed of skeletal plates called ossicles • Ossicles = small bones • In some species, such as the sea urchin, plates of the skeleton are locked together to form a rigid structure. • most sea stars and brittle stars can flex their ‘arms’ = skeleton has gaps, flexible plate junctures http://ebiomedia.com/prod/BOechinoderms.html http://en.wikipedia.org/wiki/File:Sanc0521.jpg

12. Julia Heunis Other Unique Features • Echinoderms can REGENERATE ex: sea cucumbers can eject a portion of gut in response to predators and regenerate when safe • Water vascular system (described earlier) is unique to echinoderms; varies water pressure to control tube feet • Crinoids and some brittle stars = passive filter-feeders, absorbing suspended particles from passing water sea urchins = grazers sea cucumbers = deposit feeders starfish = active hunters http://www.starfish.ch/reef/echinoderms.html

13. Julia Heunis More Unique Features • Autonomy = The spontaneous self amputation of an appendage when the organism is injured or under attack. The autotomized part is usually regenerated. • “arms” → multiples of 5; some have more because of regeneration • mutable collagenous tissue ~ connect ossicles; can maintain different positions without much effort http://www.starfish.ch/reef/echinoderms.html

14. David Lin Nervous System • Decentralized • central nerve ring surrounds gut, connect radial nerves. • Radial nerves run under each arm, coordinate movement, etc. • Do not have “brains,” but some have ganglia along radial nerves http://www.tolweb.org/Echinodermata

15. David Lin Digestive System • Complete digestive system (tubular gut), mouth to anus. (bottom to top) • Crinoidia: filter-feed, use cilia • Asteroidea: Cardiac (evert), pyloric stomach, digestive glands • Urchins: “Aristotle’s lantern” (masticatory apparatus) • Holothurians: suspension/deposit feeders, use tentacles. http://www.experiencefestival.com/a/Sea_star_-_Internal_Anatomy/id/2099728 http://userwww.sfsu.edu/~biol240/labs/lab_17hydrostaticsk/pages/echinoderm.html

16. David Lin Locomotion/Musculature • Utilize water vascular system and tube feet • Water in from madreporite, pumped into ampulla by radial canal • Ampulla contracts, water to podia • Podia contracts, water to ampulla • Podia bend, shorten allows movement (vacuum and suction) http://animaldiversity.ummz.umich.edu/site/resources/biodidac/basicechino.jpg/medium.jpg http://userwww.sfsu.edu/~biol240/labs/lab_17hydrostaticsk/pages/echinoderm.html

17. David Lin Gas Exchange • Asteroids, crinoids: dermal gills (thin epidermis) • Urchins: infolds of body wall (bursae) opening to outside • Sand dollars: modified podia on top (petaloids) which are thin-walled and flaplike. • Holothurians: highly branched hindgut called "respiratory tree" http://faculty.vassar.edu/mehaffey/academic/animalstructure/outlines/echinodermata.html

18. David Lin Circulatory System • Mostly in perivisceral coelom, enhanced by water vascular system and hemal system. • Hemal system: series of canals and spaces mostly in coelomic channels. Fluid movement by cilia. Used to distribute nutrients. No respiratory system. http://faculty.vassar.edu/mehaffey/academic/animalstructure/outlines/echinodermata.htmlhttp://www.dailygalaxy.com/photos/uncategorized/urchins_1.jpg

19. Quiz • Echinodermata have ________ symmetry as larvae, but display ________ symmetry as adults. • What allows Echinoderms to function in locomotion, feeding and gas exchange? • Sea stars can grow new arms and sea cucumbers can replace their gut after ejecting them. What feature of echinoderms does this demonstrate? • Name the stomachs of a sea star. Functions?

20. Answers • Bilateral, radial • Water vascular system • Regeneration • Cardiac, pyloric; evert and enzymes, further digestion