Tuesday, May 17, 2016

The softer side of mollusk studies

kw: natural history, natural science, museums, research, collections, photographs

I have about another week to go for my data-gathering project, and then I'll return to snail inventory. A volunteer showed me another project that is going on. A lot of jars of squids are being sorted and prepared for storage in updated cabinets. This is being done in the "wet lab" because the storage medium for soft specimens is 70% alcohol. The wet lab has the best ventilation, and even then the atmosphere can get a bit heady! The current curator is a squid expert, so the squid collection is slated to grow rapidly.

People don't think of squids when they hear the word Mollusk. If they know the word at all, they think clam or snail. There are about 80,000 species of clams and snails and their nearest relatives (mussels, for example), and most folks have seen many different kinds of seashells. But we seldom encounter squids, other than an occasional bowl of Calamari soup or some chunks of "ika" (the Japanese word) at a sushi bar.

There are squids of all sizes in the oceans, from Architeuthis dux, the 50-foot (15 m) Giant Squid, down to Idiosepius pygmaeus, a bit under a half inch long (~1 cm) when at rest. Measuring a squid is tricky. Being boneless, they are very flexible. The standard measurement is mantle length; the mantle is the squid's "body". The arms can be longer or shorter than the mantle. The two tentacles can stretch to much longer than the arms, but at rest are 2-3 times as long. Thus the largest Giant Squid, or its heavier cousin the Colossal Squid (Mesonychoteuthis hamiltoni), may have a mantle length of 6.5 feet (2 m), with roughly equal arm length, but the tentacles can stretch 35-50 feet (10-15 m), leading to maximum "stretched-out" sizes for these two species of 50-60 feet (18 m).

About 300 squid species are known, but almost every mid-ocean collecting cruise brings back specimens or photos of a new species.

This small jar is about 4 inches high (10 cm), holding a specimen about two inches in mantle length. This is a full grown adult of this species. It is a little smaller than the ones used for Sushi or Calamari soup. Species from this size up to about the size of your arm are the most common, and are a food source for sharks and other predatory (and quick-reacting) fish.
The jar seen just above is at the lower right in this image, next to another specimen of similar size and a jar containing three specimens of a much larger spotted squid. Their mantle length is close to a foot (0.3 m). I didn't read the labels, so I don't know the species of any of these.

Keeping a squid collection is a bit like keeping a caterpillar or spider collection. They don't dry out well so you need to preserve them in alcohol. Many people enjoy collecting seashells or insects, because the shells arrive at the beach already cleaned out and easily dried, and insects dry out readily. But softer-bodied critters are only collected by those who really love the subject. I don't think we have any specimens of squid that somebody just walked in saying, "Hi, I picked this up at the beach the other day and I thought the museum might like to have it." It happens with seashells, all the time. Squids? Not so much. But our curator loves studying these softer, but not necessarily gentler, mollusks (all squids are predators).

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