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No. 117: May-June 1998

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Kinky Sex Among The Invertebrates

We suspect that the following two items may embarrass some, but they are too weird and amusing to ignore.

Love's arrow. Or, rather, love's giant hypodermic needle. Cupid's arrows are rather benign compared with those of some squid. Some small squid will use their sharp beaks or tentacle hooks to rip open the skin of females. They then insert spermatophores with their penises. In the giant squid, however, the male's penis is formidable, muscular, and almost a meter long. It is powerful enough to insert spermatophores directly under the skin of the females. The males are not always accurate, for males themselves are sometimes impregnated in this manner during the squids' deep-sea orgies.

(Norman, Mark D., and Lu, C.C.; "Sex in Giant Squid," Nature, 389:683, 1997.)

The free-style penis. In the octopus and many cephalopods, the males have a special tentacle with which they insert their spermatophores under the mantle of the female. The tentacle is then retracted for future use.

The male paper nautilus is more profligate with its tentacles. The paper nautilus is cephalopod which, like its cousin, the chambered nautilus, "sails the unshadowed main."* When the male detects a receptive female, he avoids intimacy. It's sex at a distance. His spermatophore-bearing tentacle detaches itself from the body and swims -- under its own power -- to the female, being in effect a swimming penis.

Just how this peculiar arrangement evolved is anyone's guess. Perhaps it has something to do with the fact that the female paper nautilus still retains a molluscan shell, while the male has lost this armor and looks more like an aspiring octopus. Without a shelly defense, the male may not want to get too close to the female!

(Anonymous; "The Shell of Aphrodite," Nature, 391:550, 1998.)

*Apologies to Oliver Wendell Holmes for using his words in this racy context.

From Science Frontiers #117, MAY-JUN 1998. � 1998-2000 William R. Corliss