PHYLUM ECHINODERMATA

1. class Echinoidea class Asteroidea (sea urchins, sand dollars, sea biscuits) (starfish) PHYLUM ECHINODERMATA class Ophiuroidea M. Benjamin Cowan class Crinoidea class Holothuroidea (brittle stars, basket stars) Paddy Ryan (feather stars, sea lilies) (sea cucumbers) upper 2 photos by J. Hodin

2. some factoids about echinoids.... • no "head" per se • nervous system: nerve ring with radial nerves • rigid dermal skeleton with mutable collagen; specialized nerves controlling lantern • miscellaneous specializations: spines, tube feet, pedicellaria, "Aristotle's lantern", much more rigid skeleton ("test") than other echinoderms • predators include sea otters, starfish, lobsters, birds, humans, octopods • approx. 1000 living species, all marine • triploblasts; five-fold symmetry as adults, bilateral as larvae • all are male-female • usually external fertilization, some brood • all adults are benthic • most are grazers, some are predators, deposit or suspension feeders • many have feeding larvae - pluteus http://www.microscopy-uk.org.uk/ mag/artjul00/urchin2.html http://virtual.yosemite.cc.ca.us/randerson/ Marine%20Invertebrates/aristotl.htm photo by J. Hodin

3. some factoids about asteroids.... • approx. 1800 living species, all marine • triploblasts; five-fold symmetry as adults, bilateral as larvae • almost all are male-female, a few hermaphrodites • usually external fertilization, some brood • all adults are benthic • most are predators, some are grazers, a few deposit or suspension feeders • stereotypical feeding larval forms are bipinnaria/brachiolaria - many species have modified and/or non-feeding larvae • no "head" per se • nervous system: nerve ring with radial nerves; "eyes" at the tips of the arms • rigid dermal skeleton with mutable collagen • miscellaneous specializations: tube feet (often modified depending on substrate type), eversible stomach, regeneration (larvae and adults!) • predators include fish, birds, BIG snails, crustaceans, sharks, sea otters (Vickery & Mcklintock, 2000) Jan Parmentier soft-bottom hard-bottom substrate substrate

4. some factoids about ophiuroids.... • approx. 2000 living species, all marine • triploblasts; five-fold symmetry as adults, bilateral as larvae • almost all are male-female, a few hermaphrodites, some asexual • usually external fertilization, some brood • all adults are benthic • most are deposit and/or suspension feeders, some are scavengers or active predators • feeding larval form is a pluteus - many species have non-feeding larvae • no "head" per se • nervous system: nerve ring with radial nerves • rigid dermal skeleton with mutable collagen - less pronounced than in other echinoderms • miscellaneous specializations: muscular movement, autotomy as defense mechanism, regeneration (larvae and adults!), eyes!! • major predators are fish Gordon Hendler Joanna Aizenberg Ophiocoma wendtii Wim van Egmond Kerry Werry Nature 412, 819 - 822 (23 Aug 2001)

5. some factoids about holothuroids.... • stereotypical feeding larval form is an auricularia larva - many species have non-feeding larvae • no "head" per se; vermiform; more tendency towards bilateral symmetry than other living echinoderms • nervous system: nerve ring (prominent around mouth) with radial nerves • dermal skeleton reduced to ossicles with mutable collagen; hydrostatic skeleton • miscellaneous specializations: feeding tentacles; can eject sticky cuvierian tubules when pissed; can eviscerate stomach when super pissed • major predators are starfish, stomatopods, humans • approx. 1200 living species, all marine • triploblasts; five-fold symmetry as adults, bilateral as larvae • most are male-female, a few simultaneous hermaphrodites; some asexual • internal or external fertilization, many brood • most adults are benthic; but there are a few holoplanktonic sea cucumbers!! • most are deposit or suspension feeders Sumaitt Putchakarn. Mike Reich Greg Wray www.emedicine.com/emerg/topic158.htm

6. a holoplanktonic sea cucumber!! http://biomaritime.free.fr/echinodermata.html

7. some factoids about crinoids.... • filter feeders • all have non-feeding larvae • no "head" per se • nervous system: nerve ring with radial nerves; aboral concentration unique among echinoids • dermal skeleton with mutable collagen • miscellaneous specializations: pinnules for feeding; cirri make a "holdfast" • major predators are starfish, stomatopods, humans • approx. 600 living species, all marine; were once incredibly abundant in the fossil record (5000 fossil species) • triploblasts; five-fold symmetry as adults, bilateral as larvae • all are male-female • internal or external fertilization, many brood • all adults are benthic; some can swim Hiroaki Nakano (dots indicate a ciliated band) www.ucmp. berkeley.edu Charles Messing Bather, 1900

8. deuterostome larvae - common ancestry?? HiroakiNakano Greg Wray Jan Parmentier sea lily (non-feeding) sea cucumber starfish acorn worm feeding larvae acorn worm "tornaria" larva modified from: Peterson et al. (1999) Development 126:85-95

9. Escape and Aggregation Responses of Three Echinoderms to Conspecific Stimuli A. C. Campbell,* S. Coppard,C. D’abreo, and R. Tudor-Thomas Biol. Bull. 201: 175–185. (October 2001)

10. Campbell et al. (continued) A. rubens P. miliaris E. esculentus http://www.marlin.ac.uk/images /optimised/o_Astrub.jpg http://www.nhm.ac.uk/palaeontology/ echinoids/genera/echinoid/psammech.htm http://www.marlin.ac.uk/images/ optimised/o_Echesc.jpg

14. from: Carefoot (1977) Pacific Seashores

15. sea urchin density (number of individuals per 1/4 m2) a b c (i.e. 0% at all depths!) depth (m) http://www.otternet.com/galleries/seaotter/ Amchitka - many sea otters Shemya - few sea otters - a - b - c vegetation cover (%)