Cephalopods

[Class Cephalopoda]

Cephalopods, the name meaning "head footed", have been here for a very long time, some 500 million years. They first appeared in recognizable form in the last quarter of the Cambrian period. As far as we know, they all originally had shells, but today only the Nautilus has a true external shell, and it is restricted to the tropics of the Southwest Pacific. The most successful shelled cephalopods were the Ammonites (8 orders), which were extremely common for around 340 million years, but met extinction in the same ecological disaster that did in the dinosaurs. Their curled shells, some simple, some ornate, some up to 6 feet in diameter, litter the fossil beds of the world.

The most common cephalopods living today have all given up the protective shell for high mobility, but rather than discarding the shells, they have used them in innovative ways. Squids use it as a body stiffener called a Gladius, and some Octopi also have a Gladius. The Cuttlefish has evolved its shell into a porous "cuttlebone" used to control flotation. One squid-like cephalopod, Spirula, has a shell very similar to a nautilus shell, but entirely within the body, used as a flotation device. The female Paper Nautilus (genus Argonauta, actually a kind of octopus), creates a shell that is both a flotation device and a brood chamber for eggs.

Cephalopods are by far the most intelligent invertebrates. Octopi can even figure out how to remove screw caps from jars. Their intelligence, however, is composed very differently from ours. With the exception of the Nautilus, they have very sophisticated eyes, though they are different in design from ours. Their most amazing feature is the ability to almost instantly change the pattern and colors of their skin to match their background, and in the case of the cuttlefish, even change its texture.   Rendering by Nobu Tamura distributed under license Creative Commons Attribution-ShareAlike v3.0 Unported.

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Three orders of cephalopods are of culinary importance. Each of these orders has multiple detail pages linked from the paragraphs below. Octopus [Order Octopoda] Octopi are considered very good eating everywhere they are found, except North America, though even here they are easily available in our many Asian markets. There are over 300 species of Octopus worldwide, and all are venomous, but only the Blue Ringed Octopi (genus Hapalochlaena) are dangerous to humans. These small octopi carry enough venom to kill 26 adult humans.   Details and Cooking. Squid [Order Teuthida] Squid are the largest, most mobile and perhaps most intelligent of the mollusks. Giant squid grow to over 33 feet from tentacle tip to tail and Colossal Squid can exceed 46 feet. These huge squid are suspected of being among the most intelligent creatures in the sea. You will not be eating one of those because they live too deep to catch and their flesh is laced with toxic ammonia anyway. Market size squid (different species) are, however, plentiful and good eating.   Details and Cooking. Cuttlefish [Order Sepiida Genus Sepia] Cuttlefish are found in coastal waters throughout the world - except the Americas. Since they are not native to our waters, they are not as well known as Squid and Octopus, but they are easily available in our large Asian markets here in California, and very good eating.   Details and Cooking.