Sex, manual

PZ Myers sure loves squid. (And who doesn't? I like mine best a la plantxa, served with a bit of lemon and a glass of Milmanda.)

Someone (was it the earl of Rochester?) once said that sex feels so good to compensate for its looking so ridiculous. Myers shows us what it looks like when squid do it, and for their sake it ought to feel very good indeed.

Myers also told me something I did not know:

Male squid do not have a penis. Instead, they have a pouch that opens into the mantle cavity, called Needham's sac, where spermatophores are stored, and they have a specially modified tentacle, the hectocotylus, which is used to reach into the sac, scoop out a spermatophore, and and place it inside the buccal or mantle cavity of the female. In some cephalopods, the end of the hectocotylus snaps off and remains imbedded in the female.

Now that I found very interesting. Squid are not the only creatures that employ this indirect and we might say manual method of insemination. (This means of impregnation has not, of course, evolved among humans, though I believe it played a role in Vonnegut's Galapagos.) Spiders do something very similar. Pick up a male spider and look at him carefully. You'll note what seems to be a smaller, fifth pair of legs, just in front of the first pair of 'real' legs. These are the pedipalps (and they are homologous to the lobster-like claws of the spiders' cousins, the scorpions). Your male spider will look as though he is wearing a wee pair of boxing gloves on the ends of his palps. Before he goes looking for love, he secretes a droplet of sperm onto a bit of web, then sucks it up into his boxing gloves. Assuming he gets lucky, he will insert his palp into his mate and fill her with sperm (though the eggs will not be fertilised until they are laid). In the 'higher' spiders, the tip of the palp fits into the epigyne, a sclerotised plate on the female's abdomen, much as a key fits into a lock. (It's thought that this prevents breeding between species, though differences in mating behaviours might well be what really does that.) And like some of Myers's squid, some male spiders leave the tip of their palp in the female, the better to frustrate their rivals.

We may add male spiders, then - and, as I have now learned, male squid - to that select group of animals (including teenage boys) for whom the hand is the primary sexual organ.