The Dredge Report… Wizard islet residents temporarily missing

Sunday, February 12th, midday, numerous residents from around Wizard islet were swept up into a heavy net, only to be returned approximately half an hour later. Sally Snail, one of the residents who was temporarily taken to the surface said: “I saw absolutely nothing. I was holding my breath inside my shell the entire time!”

That is how a news article might start if the marine community from around Wizard islet, just off the coast from the Bamfield Marine Science Centre (or BMSC for short,) had a newspaper… and could read… and write… and also choose interviewees poorly.

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Wizard islet peeking out of the water. (Photo credit to Brianna Cairns.)

Last weekend, while at BMSC, we took a trip out on the centre’s flagship, the Alta, to conduct a dredge and look at ocean floor life. Normally a dredge involves scraping out large areas of ocean, sea, or lake floor, however the dredges that take place out of BMSC follow strict guidelines. For example, they only dredge the sandy floor around one small, magical islet, and the metal frame that holds the net is only about 45cm across.

Which brings us back to what we dredged up; the animals local to the locale: Various sea stars, urchins, bottom fish, small crabs, clams, mussels, sea cucumbers, and the most interesting to me, moon snails.

Sally didn’t make a very good interviewee because when in danger, moon snails lock themselves tightly inside of their shells with a hard plate sealing the opening. This protects them, but has a drawback; they seal the opening so well that they cannot breathe meaning that cannot stay inside indefinitely. I was also astonished by the size of these snails. Bellow you can see our TA holding one that is approximately baseball sized, and that is only about half their maximal size!

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Our TA holding a Moon snail and various other activity.

We also found some perfectly circular material that I would describe as looking like the top of an old timey vase, about 15cm in diameter. I assumed that it was some kind of garbage, like a gasket from a boat and I was surprised to learn that it was made by a moon snail! Looking closely at these “sand collars”, I could see that they were made of grains of sand gelled together giving them a smooth, rubbery finish. Their purpose? Moon snails place a layer of eggs inside the collars which serves to disperse and protect the eggs. Intrigued? If you want to learn more about moon snails or see some cool videos, you can follow the links at the bottom.

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Me holding a piece of a sand collar. (Photo credit to Sharon Kay.)

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A closer look at a sand collar beside a moon snail. ( Image from http://www.asnailsodyssey.com/LEARNABOUT/MOON/moonPred.php )

Moon snail fact sheet: http://animaldiversity.org/site/accounts/information/Euspira_lewisii.html

Moon snail time lapse: https://www.youtube.com/watch?v=6e2MFmg0i7c

Sand collar: https://www.youtube.com/watch?v=1XGtkYsPJaI

For those of you with adventurous tastes, recipes are available online. Here is one on the Stripersonline.com forum. That is stripersonline, not strippersonline. If you use the two P website, you may be in for a surprise.

http://www.stripersonline.com/surftalk/topic/534203-moon-snails/

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