By Dave Sigworth, publicist of The Maritime Aquarium
You’ve probably seen soft-shelled crabs on restaurant menus. But have you ever seen a soft-shelled lobster?
How about a soft-shelled blue lobster?
There’s one at The Maritime Aquarium today (9/4).
Crabs and lobsters have hard shells, or exoskeletons, of course. To be able to grow, they have to break out of their old shell – a process called molting. They’ll squeeze out of a crack in the old shell, take in seawater to swell up to a larger size – about 15 to 20 percent bigger – and then wait for their new exoskeleton to harden. This will take a while, and it is during this period that they are “soft-shelled.” [Actually, the term tends to be “soft-shelled” for crabs but “shedder” is more commonly used for lobsters.]
When lobsters are younger and growing more rapidly, they’ll molt as many as 25 times in their first 5 to 7 years. (Water temperature can affect the growth rate but generally it takes about 7 years for a lobster to reach “legal” size.) Mature lobsters grow more slowly and molt only about once a year.
Inside the new shell, a “shedder” lobster releases some of the seawater it had taken in to swell up. It now has some room to grow – like the strategy parents use when buying slightly oversized clothes for teen-aged boys.
Lobsters are defenseless after molting, so they tend to hide. However, this is also the only time that females can mate. They’ll give off a scent, or pheromone, to lure males into their hiding place.
Meanwhile, aside from one crack, the old shell is a perfect, slightly smaller twin of the lobster – the antennae, claws, legs, mouth parts, even the covering over the eyes.
Often, the lobster will eat its old shell to regain some of the shell’s calcium and other minerals. So as a Maritime Aquarium visitors’ heads-up: if you see what appears to be a lobster eating another similarly sized lobster, that’s what’s happening. No need to be alarmed.
Now back to that lobster that molted overnight at the Aquarium: why is it blue? Lobsters can have odd colorations because of genetic flukes. Blue lobsters are said to be a once-in-a-couple-million occurrence.
The new exoskeleton of our blue lobster is a brilliant unmarred cobalt blue.
And, finally, the obvious question: can you eat a “shedder” lobster? Absolutely. In fact, some people specifically seek out “shedders,” believing the meat to be sweeter. Certainly their shells are easier to crack. The drawback to “shedders”: because the lobster hasn’t grown into its new shell, you tend to get less meat.