EPOW - Ecology Picture of the Week

Green Urchin of the Islands

Green Sea Urchin (Lytechinus semituberculatus), Family Toxopneustidae
Floreana Island, Galapagos Islands, Ecuador

Explanation:  Commonly found within its tiny distributional range is this beautiful echinoderm, the green sea urchin of the Galapagos Islands and coastal Ecuador, South America.  

Apparently, this species is genetically indistinguishable from the species Lytechinus panamensis although the two species appear different.  This is a puzzler.  

And common it is, with up to 70 individuals found per square meter in the western part of the Galapagos Islands.  I found these individuals along the beach of Floreana Island in eastern Galapagos, however, where apparently it has not been reported (see map at this Charles Darwin Foundation page).  

Information:
     Watts, S.A., J.B. McClintock, J.M. Lawrence.  2013.  Ecology of Lytechinus.  Chapter 23 in: J.M. Lawrence, editor.  Sea urchins: biology and ecology.  Elsevier, N.Y.
     Watts, S.A., J.B. McClintock, J.M. Lawrence.  2013.  Lytechinus.  Chapter 31 in: J.M. Lawrence, editor.  Sea urchins: biology and ecology.  Elsevier, N.Y.
     Zigler, K.S. and H.A. Lessios.  2004.  Speciation on the coasts of the New World: Phylogeny and the evolution of bindin in the sea urchin genus Lytechinus.  Evolution 58(6):1225-1241.