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Donax variabilis Say, 1822 with hydroid |
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During the summer and fall months a significant portion of the
specimens found on northeast Florida beaches have a hydroid
"plume" attached to the posterior aspect of the shell (the short end; the
upper end when burrowing; the end with the siphons). Over the years this
phenomenon has been a continuing source of amazement to those observing it
for the first time and has generated many questions. A study of
the sibling species Donax fossor indicates predation by Neverita duplicata (Shark Eye; Moon Snail) was affected
by the presence of a hydroid colony. Donax without a
hydroid colony were drilled more frequently than those possessing
it, which suggests that the Donax benefits from the hydroid by way
of predator deterrence. The reduced predation supports the case
that this symbiosis is an instance of mutualism. See: http://findarticles.com/p/articles/mi_m0QPU/is_1_24/ai_n13807881 |
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Below - buried in the substrate |
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Little Talbot Island State Park, Duval County, Florida 7/26/2004 (shell about 14 mm.) |
