Happy as a . . .

. . . clam, right? Yes, except in this case the bivalve is not a clam, but a scallop. I was out at the harbor with Brenna again this morning, looking for molluscs for tomorrow's molluscan diversity lab. Brenna was hunting for slugs, of course, and had drawn up a rope that had been hanging in the water for god knows how long. Neglected ropes like this are the stuff of dreams for people like Brenna and me, as all sorts of animals recruit to and colonize them. Hauling one up is like going on a treasure hunt.

Two of the animals that had attached to the rope were small kelp scallops, Leptopecten latiauratus. The smaller of the two was about the size of my thumbnail and the larger was about 1.5 times that size. Their shell patterns are very beautiful:

The larger rock scallop (Chlamys hastata) collected at the Santa Cruz Yacht Harbor. 14 September 2015 © Allison J. Gong
The larger kelp scallop (Leptopecten latiauratus) collected at the Santa Cruz Yacht Harbor.
14 September 2015
© Allison J. Gong
The smaller rock scallop (Chlamys hastata) collected at the Santa Cruz Yacht Harbor. 14 September 2015 © Allison J. Gong
The smaller kelp scallop (Leptopecten latiauratus) collected at the Santa Cruz Yacht Harbor.
14 September 2015
© Allison J. Gong

But really, you don't get a feel for how much fun these animals are until you watch them. Scallops are the most animated of the marine bivalves. They have eyes and sensory tentacles along the ventral edge of the mantle, and react strongly to stimuli. They can clap their valves together so quickly that they actually swim. I wasn't able to make either of mine swim, but did get to watch them for a while.

The whitish object waving around on the left side of the frame is the scallop's foot. Rock scallops are not permanently attached to surfaces (if they were, they wouldn't be able to swim!) but they do use the foot to stick. If they find a spot they like, they try to wedge the dorsal, hinged area of the shell into a crevice.

Just like you and me, scallops have bilateral symmetry, complete with left and right sides. Unlike you and me, however, their bodies are laterally flattened and entirely enclosed between the left and right shells. The only parts of the body that extend from between the shells are the foot and the sensory structures on the mantle edge. Leptopecten has many long filament-like sensory tentacles, and brilliant blue eyes.

I thought I'd provoke a reaction by passing my finger over the animal and casting a shadow over it. Nada. But then it closed its shells a couple of times for no reason that I could discern. However, as my graduate advisor Todd Newberry used to say, The Animal Is Always Right™, and what doesn't seem like anything to me could very well be a threat to a scallop.

And by the way, I did also collect a few slugs and a chiton for tomorrow's lab. The highlight for me, though, was the scallops. I hope my students are as captivated by these little bivalves as I was!

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