Eusmilia spawning

Boland, Gregory Gregory.Boland at
Fri Oct 26 16:37:53 EDT 2001

Coral List,

This is in response to Dirk Peterson's request for information on Eusmilia
fastigiata spawning.  I thought it would be useful to post these images to
the whole list even though David sounds like he is concentrating on the
spawning behavior of this species for his graduate work.   I indirectly
acquired this image from a tourist/diver many years back when I was involved
with the team that documented the first in situ mass spawning event in the
Atlantic/Gulf /Caribbean in 1991 and the first Colpophyllia natans spawning
in 1994.  This is an incredible image and I have always been puzzled about
what is exactly going on.  It was taken in French Cay of the Turks and
Caicos Islands (not sure which island exactly) on August 28, 1994 at about 9
PM.  The full moon for August, 1994 was on the 21st at 23:48 so the image
was taken 7 evenings after the full moon.

The gametes appear to be individual eggs, much smaller than gamete bundles
of Montastrea or Diploria species.  I don't know if Eusmilia is dioecious.
The strangest aspect is that the gametes or "eggs" are accumulated inside
the expanded polyp tentacles.  One would speculate that the eggs might be
released through the end of the tentacles, but this seems very odd.  They
are getting out from somewhere as there are many gametes visible in the
surrounding water.  Could be the gametes in the tentacles are trapped and
should have been retained in the gastrovascular cavity for release through
the mouth as other taxa do.   

The close-ups are from the same image, only cropped and scanned at the
highest resolution I could squeeze our of my Coolscan III.

It is my understanding the photographers have no concerns about photo credit
but here are their names anyway, as I have always been  a stickler for photo
credit , particularly for underwater images.

Photos by: Anne Owen and David Wheeler, 1994

Greg Boland
Biological Oceanographer
Minerals Management Service

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