To mate, this octopus gives life and limb

The tiny male argonaut lodges a detachable, sperm-bearing tentacle in a female up to 30 times his size.

Lest you doubt the awesome power of the drive to procreate, consider what Mr. and Mrs. Argonaut (Argonauta argo) must go through to send baby argonauts out into the world.

This octopus species lives in open water in Earth’s tropical and subtropical seas. It’s not the easiest place to find a mate, especially since the male is tiny—less than three-quarters of an inch long—while the female can be up to 30 times his size. She has two specialized dorsal arms that secrete a chalky substance, forming a pleated shell in which she can hide, float, and brood eggs. The male is sans shell, but he too has a specialized arm: a tentacle-like, detachable copulatory organ called a hectocotylus.

After attaching to the female, the male releases his hectocotylus, which worms its way into the female’s mantle cavity. She may stockpile these disembodied sperm arms from several mates and use them to fertilize her eggs over time. She’ll lay strings of eggs tethered to her shell (also called an egg case) where she can tend them as they develop. Scientists know this because they’ve been able to observe argonaut mothers live—but not fathers.

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