Echinodermata

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Since they are almost exclusively marine species, echinoderms are probably osmoconformers, with little ionic regulation.

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Echinus (sea urchin):

Echinus is a genus of sea urchins.

Species[edit]

Species in this genus include:[1]

References[edit]

  1. ^ http://www.marinespecies.org/aphia.php?p=taxlist accessed 11 August 2010

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Echinoderms are usually intricate parts of their ecosystems. Many asteroids are keystone species. Sea urchins, if not controlled by predators, may overgraze their habitat. Asteroids have several commensals, including polychaetes that feed on leftovers from the sea star's prey items.

Ecosystem Impact: keystone species

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Echinoderms in general are most vulnerable in their larval stage. As adults, asteroids have an anti-predator adaptation where they can lose an arm to a predator and the arm is later regenerated. Holothurians discharge sticky tubules, known as   Cuvierian tubules , at a potential predator. Otters prey mainly on sea urchins.

Known Predators:

  • otters (Lutrinae)
  • flounders (Pleuronectidae)
  • haddock (Melanogrammus)
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Known predators:

Echinodermata is prey of:
Pycnopodia
Merluccius bilinearis
Urophycis tenuis
Gadidae
Melanogrammus aeglefinus
Hemitripterus americanus
Myoxocephalus octodecemspinosus
Leucoraja erinacea
Leucoraja ocellata
Amblyraja radiata
Macrozoarces americanus
Anarhichas
Tautogolabrus adspersus
Pleuronectes americanus
Hippoglossoides platessoides
Mustelus canis
Lophius americanus
Caretta caretta
Corvus caurinus
Enhydra lutris

Based on studies in:
USA: Washington, Cape Flattery (Littoral, Rocky shore)
USA, Northeastern US contintental shelf (Coastal)

This list may not be complete but is based on published studies.

  • R. T. Paine, Food webs: linkage, interaction strength and community infrastructure, J. Anim. Ecol. 49:667-685, from p. 670 (1980).
  • Link J (2002) Does food web theory work for marine ecosystems? Mar Ecol Prog Ser 230:1–9
  • Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web (online). Accessed February 16, 2011 at http://animaldiversity.org. http://www.animaldiversity.org
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Known prey organisms:

Echinodermata preys on:
detritus
benthic macrofauna
Bivalvia
algae
Ostreoida

Based on studies in:
USA: Rhode Island (Coastal)
USA: Alaska, Torch Bay (Littoral, Rocky shore)
USA: Washington, Cape Flattery (Littoral, Rocky shore)
USA, Northeastern US contintental shelf (Coastal)

This list may not be complete but is based on published studies.

  • J. N. Kremer and S. W. Nixon, A Coastal Marine Ecosystem: Simulation and Analysis, Vol. 24 of Ecol. Studies (Springer-Verlag, Berlin, 1978), from p. 12.
  • R. T. Paine, Food webs: linkage, interaction strength and community infrastructure, J. Anim. Ecol. 49:667-685, from p. 670 (1980).
  • Link J (2002) Does food web theory work for marine ecosystems? Mar Ecol Prog Ser 230:1–9
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Rights holder/AuthorCynthia Sims Parr, Joel Sachs, SPIRE
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The non-centralized nervous system allows echinoderms to sense their environment from all sides. Adult pheromones may attract larvae, which tend to settle near conspecific adults. Metamorphosis in some species is triggered by adult pheromones.

Communication Channels: chemical

Other Communication Modes: pheromones

Perception Channels: tactile ; chemical

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Echinoderms are deuterostomes. The larvae, which are planktotrophic or lecithotrophic, have 3-part paired coeloms. Embryonic coelomic structures have specific fates as the bilaterally symmetrical larvae metamorphose into radially symmetric adults. Adult pheromones may attract larvae, which tend to settle near conspecific adults. Metamorphosis in some species is triggered by adult pheromones.

Development - Life Cycle: metamorphosis

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Brief Summary:

Echinodermata is an entirely marine taxon, occurring throughout the world’s oceans and includes sea stars, brittle stars, sea urchins, sand dollars, sea cucumbers, and sea lilies. Echinoderms are tricoelomate deuterostomes, with a simple hemal/excretory system, decentralized nervous system, and (in most species) separate sexes, with planktonic larvae settling to become benthic adults.

Distinguishing characteristics:

1. Pentamerous symmetry in adults, though larvae are bilaterally symmetrical.

2. Hard endoskeleton of calcareous ossicles, either loosely connected (e.g., brittle stars) or tightly bound (e.g., sea urchins).

3. Water vascular system involved in feeding, locomotion, and respiration.

4. Mutable dermis and connective tissue that, under the control of the nervous system, can fluctuate between extremely rigid and essentially fluid.

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Reproduction:

Mating System: polygynandrous (promiscuous)

Echinoderms are mainly gonochoristic (having separate sexes), with exceptions among the asteroids, holothurians and ophuroids. Holothurians possess a single gonad, crinoids lack distinct gonads, while asteroids and echinoids have multiple gonads. Echinoderm reproductive strategies vary from free spawning and indirect development to brooding and direct development. Spawning is probably a noctural event.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); simultaneous hermaphrodite; sequential hermaphrodite; sexual ; fertilization (External ); oviparous

Parental investment ranges from no care after the release of eggs for free spawning to brooding the young. Brooding is found in polar and boreal echinoderms and some deep sea echinoderms, where environments are more difficult for the larvae.

Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Provisioning: Female, Protecting: Female)

  • Brusca, R., G. Brusca. 2003. Invertebrates. Sunderland, Massachusetts: Sinauer Associates, Inc..
  • Barnes, R. 1987. Invertebrate Zoology. Orlando, Florida: Dryden Press.
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Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith