Today is the first guest post featured on Our Wild World! Isn’t it exciting?! Due to sickness, midterms and assignments, I was unable to find time today to post. But instead of leaving you, my dear readers, without something to read on this fine Wednesday, I enlisted the help of a good friend of mine. She’s working on her masters at Memorial University in Newfoundland, and is studying scallops. Unsurprisingly, she chose to write about scallops. So here it is, and enjoy:

Scallops are a type of bivalve mollusc found in oceans all over the world.  They’re related to clams and mussels, and like all bivalve molluscs have two shells that fit together and cover their entire body.  Scallops and their relatives can close these shells for protection from predators and also to prevent drying out if they happen to find themselves out of water for an extended period of time (like at low tide when water levels have dropped lower than normal).  These shells can also be used as a musical instrument (probably) if you happen to find yourself on the sea floor in desperate need of a mariachi band.*  The body of a scallop consists of a large internal muscle (the thing you eat if you order scallops in a restaurant), a pretty standard digestive system (for a bivalve), a pretty standard reproductive system (for a bivalve), a bunch of other organs (but no brain!), some gills for breathing, two mantles (the body part just inside the edge of the shells), and up to 100 eyes (more about these later, they’re pretty cool!).

 

The Atlantic Sea Scallop showing off its shell, its mantles (the stripey bits), and several of its eyes.
The Atlantic Sea Scallop showing off its shell, its mantles (the stripey bits), and several of its eyes.

Scallops live on the ocean floor in areas called beds.  Each bed can be home to thousands (or hundreds of thousands) of scallops, and in many areas these beds are fished commercially using dredges and trawls (nets that drag along the sea floor, picking up anything that gets in their way).  My favourite scallop, the Atlantic sea scallop (Placopecten magellanicus) is found along the eastern seaboard of North America, from the northern shores of the Gulf of St. Lawrence to the coast of North Carolina, but other species are found in every ocean on the planet.

The coolest things about scallops (in my opinion) are the eyes. Unlike other bivalves (most of which don’t see at all), scallops have dozens of bright blue eyes around the edge of their mantles.  These eyes can’t see shapes, but they contain 2 retina types that allow scallops to detect changes in light intensity and movement (like a predator moving in for the kill).

Being able to detect predators moving around gives scallops a chance to escape by – get this – swimming!  I don’t know about you, but swimming is not the first thing I think of when bivalves come to mind (think of mussels attached to a pier or clams hanging out in the mud), but the scallop seems to like to break the mold.  They swim by using their internal muscle to squeeze their two shells together, shooting water out of the gap and propelling themselves forward, all the while looking pretty ridiculous.  Check out this video to see this fantastic feat in action:

http://www.youtube.com/watch?v=_2iXHBuSIJY

They might not be able to get very far, but I still think it’s maybe the coolest thing I’ve ever seen shellfish do.

*Disclaimer: Please do not try to use scallops as a musical instrument.

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