Sea Hares (Stylocheilus polyyomma) swarming, March 2nd - 6th 2010, Bonaire, Netherlands Antilles
Massive swarming behavior in Sea Hares (Stylocheilus polyyomma) has been reported, on occasion, from different locations around the world (including Bonaire). I believe it is a last hurrah. The second day I observed the Sea Hares there were many eggs trails winding throughout the sand, so in probability this is a mass spawning event. Soon after laying their eggs the Sea Hares will weaken and die. I noticed one group further up the reef from where the ones I photographed were and they were already in a very weakened state and fewer in number. The first day I observed the Sea Hares (3/2/10) I would say there were literally millions of them. There were long lines of Sea Hares all crawling in one direction until they would arrive at the huge groupings. The second and third day there were thousands and with each passing day their numbers decreased until Saturday evening, March 6th, I saw perhaps a hundred. The last photo includes a short video clip.
Two more short video clips here (please excuse the terrible quality!)
http://www.youtube.com/imaginebonaire