Green Sea Urchin
|These three S. droebachiensis were found on a dredge in Friday Harbor|
|Photo taken by Heidee Leno. July 2002|
How to Distinguish from Similar Species: Since juvenile S. purpuratus urchins may have pale green spines, S. droebachiensis may be mistaken for them. S. pallidus, a deep subtidal species, is a lighter green and its tube feet are as light or lighter than its spines.
Habitat and Range: In both sheltered and exposed kelp beds and rocky areas, located in the low intertidal zone and subtidal zone to 1,200 meters in the Atlantic Ocean. These urchins range from Alaska to the Puget Sound. They may also be found on the Atlantic coast and in Europe. This and S. pallidus are the only species of urchin in the Puget Sound area that are also found in the NW Pacific off Russia (Bazhin, 1998). Bazhin also says that the species is sometimes found but is not common in many areas of the Arctic Ocean so it should not necessarily be considered a circumpolar species.
Biology/Natural History: S. droebachiensis feed on large algae such as bull kelp, green algae, and laminarians, they also scrape diatoms and coralline algae off rocks. They are harvested commercially for their roe, which is a delicacy in Japan. In the Gulf of Maine, males at widely separated populations seem to be release sperm at similar times, suggesting that they are responding to a widespread environmental signal. Spawning was most intense during full and new moon (spring tides). However, extensive sperm release seems to occur mainly in large urchin swarms, suggesting that the presence of spawning of nearby urchins triggers spawning by others (Gaudette et al., 2006). In the Barents Sea, Russia, spawning peaks late February to April, in temperatures ranging from 0.4 to 1.8 C (Oganesyan, 1998).
Microsatellite analysis (Addison and Hart, 2004) shows strong population
differentiation between Pacific and Atlantic populations. This shows
there is little gene flow between the Atlantic and Pacific populations.
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Flora and Fairbanks, 1966
Kozloff 1987, 1996
Smith and Carlton, 1975
Lambert and Austin, 2007
Addison, J.A. and M.W. Hart, 2004. Analysis of population genetic structure of the green sea urchin (Strongylocentrotus droebachiensis) using microsatellites. Marine Biology 144:2 pp. 243-251. DOI:10.1007/s00227-003-1193-6
Bazhin, A.G., 1998. The sea urchin genus Strongylocentrotus in the seas of Russia: Taxonomy and ranges. pp 563-566 in Rich Mooi and Malcolm Telford (eds), Echinoderms: San Francisco. Proceedings of the Ninth International Echinoderm Conference, San Francisco, California USA 5-9 August 1996.
Gaudette, Julien, Richard A. Wahle, and John H. Himmelman, 2006. Spawning events in small and large populations of the green sea urchin Strongylocentrotus droebachiensis as recorded using fertilization assays. Limnology and Oceanography 51:3 pp. 1485-1496.
Leddy, H.A., 1998. Walking versus breathing: Functional morphology of oral and aboral podia from the green sea urchin, Strongylocentrotus droebachiensis. p 730 in Rich Mooi and Malcolm Telford (eds), Echinoderms: San Francisco. Proceedings of the Ninth International Echinoderm Conference, San Francisco, California USA 5-9 August 1996.
Lyons, Devin A. and Robert E. Scheibling, 2007. Differences in somatic and gonadic growth of sea urchins (Stronglyocentrotus droebachiensis) fed kelp (Laminaria longicruris) or the invasive alga Codium fragile ssp. tomentosoides are related to energy acquisition. Marine Biology 152:2 pp. 285-295. DOI:10.1007/s00227-007-0682-4
McEdward, Larry R. and Benjamin G. Miner, 2006. Estimation and interpretation of egg provisioning in marine invertebrates. Integrative and Comparative Biology 46:3 pp 224-232
Oganesyan, S.A., 1998. Reproductive cycle of the echinoid Strongylocentrotus droebachiensis in the Barents Sea. pp. 765-768 in Rich Mooi and Malcolm Telford (eds), Echinoderms: San Francisco. Proceedings of the Ninth International Echinoderm Conference, San Francisco, California USA 5-9 August 1996.
Selden, Rebecca, Amy S. Johnson, and Olaf Ellers, 2009. Waterborne cues from crabs induce thicker skeletons, smaller gonads and size-specific changes in growth rate in sea urchins. Marine Biology 156:5: pp. 1057-1071. DOI:10.1007/s00227-009-1150-0
Wheatley, K., R.G. Brown, and R.E. Scheibling, 1998. Coelomocyte
oxidative activity of the green sea urchin (Strongylocentrotus droebachiensis)
following challenge by bacterial and amoebic pathogens. pp. 881-886
in Rich Mooi and Malcolm Telford (eds), Echinoderms: San Francisco.
Proceedings of the Ninth International Echinoderm Conference, San Francisco,
California USA 5-9 August 1996.
Kodiak Laboratory, Alaska Fisheries Science Center, www.afsc.noaa.gov/kodiak/photo/grurch.htm
Marine Life Information Network for Britain and Ireland- MarLIN, Species Information for Strongylocentrotus droebachiensis, www.marlin.ac.uk/demo/Strdro.htm
This species is abundant subtidally in rocky areas of Northwest Island and Sares Head.
In this view, several stalked pedicellariae can be seen waving around among the spines in the center of the picture.