We're on Bonaire now thought other divers here might find this interesting to look for on the reef. On Wednesday about 3:30 pm at Sweet Dreams we found "smoking" yellow tube sponges. These sponges were releasing a cloud of ? gamates? from their center exhaust holes. The sea was so calm some groups were in a thick cloud of tiny yellow-green particles. In others it was a definate upward spiraling trail. We were in 40' to 50' of water and started examining all the groups we could find. It seemed like most were still extruding small amounts of these chartruse particles. We did get pictures (slides).
Two days earlier about the same time in the aftermoon at Angel City we found the yellow-green ube sponges and the dark yellow-green-brown knobby rope sponges "smoking." We can't ID that sponge better, don't have a detailed reference book for sponges here. These were the ones that get 4 to 6 feet long and intertwine. These sponges don't have a single central atrium but extruded through the many small holes scattered along the "rope".
Last year in the first week of July we also found the yellow tube sponges smoking on an afternoon dive. We're here for another 11 days and will continue to look in the afternoon.
Does anyone know more details?. Is it related to the full moon? Does it happen for several days a month. Any biologists or naturalists reading?
Mona and Gary

The coral was spawning. It does happen around the full moon period I believe. Caren at Sea & Discover could answer this better but I don't have her e-mail address here at work. Also Linda you could probably answer the more technical questions on this one.

Hi there Mona & Gary, wow, how exciting for you both.. here's what I can tell you, hope it helps? Sponges reproduce by both asexual and sexual means. Most poriferans that reproduce by sexual means are hermaphroditic and produce eggs and sperm at different times. Sperm are frequently "broadcast" into the water column. That is, sperm are created, concentrated and sent out the excurrent openings, sometimes in masses so dense that the sponges appear to be "smoking". These sperm are subsequently captured by female sponges of the same species. Inside the female, the sperm are transported to eggs by special cells called archaeocytes. Fertilization occurs in the mesenchyme and the zygotes develop into ciliated larvae. Some sponges release their larvae, where others retain them for some time. Once the larvae are in the water column they settle and develop into juvenile sponges. I believe that it's the right time of year for this event..

i guess with a dive mask on no one will get a "wad" in the eye;-)

hee hee...

Tsk :-)

The sperm "smoke" isn't nearly that solid.

And sponges are on a different reproductive cycle than corals, although not far off, and different sponge and coral species also have different spawning dates relative to each other.

Other critters have similar spawning events. For example, about a week ago we put a variegated urchin in our aquarium, and were surprised to see it dumping huge amounts of eggs that evening in the tank - we read up on this and found that urchin eggs are a fish delicacy. More surprising was when the following night, the same urchin started "smoking". The aquarium water got real smokey real fast - had to fish out the urchin, place it in a place with more "privacy" (a bucket of sea water) until it finished it's thing (took well over an hour total), and then replaced about 30% of the tanks water with fresh sea water.

By morning the tank was clear again. We ended up reading up on urchin spawning quite a bit though, finding it very interesting that much like many other ocean critters, some species of urchins can produce both eggs and sperm, although it's not clear to us whether they can self-fertilize or not (some corals which produce both cannot self-fertilize).

Jake

PS Gary & Mona - it was nice running into you at the post-clean-up BBQ on Saturday!

Jake

Jake, how exciting..

Here's more educational stuff for you and others..

Corals are animals, and like all other life forms, must reproduce to maintain or increase their numbers. Some coral colonies die each year from both natural and man-made causes, including typhoons, crown-of-thorns starfish, coastal runoff, sedimentation, anchor damage, and sewage impact. Unless these corals are replaced through successful reproduction followed by settlement and metamorphosis of the coral seed called planula larvae, the reef goes into decline, and the important functions and benefits of the coral reef are lost. The spawning of some coral occur around September time..

Sea Urchins -

These species undergo sexual reproduction, with external fertilization. Although hermaphrodites may occur, the sexes are generally separate. I expect you're looking forward to seeing your tiny juvenile urchins.. :)

Thanks for the information on the sponges. There's a few more words in out vocabulary now!
We are hoping to see the coral spawning on one of our trips, maybe this September. We haven't booked our return.

If anyone is interested, I have an Excel spreadsheet with the dates, times and species of the upcoming coral spawning in September and October. Just send me an e-mail and I'll send it to you as an attachment (virus free of course)

Hi Jack.

Yes, I'd be interested in a copy of the Excel chart. [bonairetrip@aol.com]

and, while I have you, does Habitat rent small (5 to 10 liter) Nitrox cylinders and pony bottles for use on my Drager Dolphin when I am in Bonaire this fall?

George K

George, e-mailed you the info this morning.

Jake,
the eggs of the sea urchin are a delicacy. In sushi bars they are referred to as uni (one of my favorites).

Also climbing in popularity in the trés chic non-sushi restaurants frequented by Miz Martha."It's a good thing'. Kinda 'the new Chilean Sea Bass' or Squid Ink Pasta. Keep an eye on your urchins. Many chefs finally began refusing to buy or serve sea bass because the populations were reported seriously under pressure.

That's why the consistency/texture seemed familiar! Linda was reading that most of the inner cavity of sea urchins is filled with masses of eggs. Not a big Uni fan myself though... :-)

Jake