National Geographic : 1991 Mar
SHYNESS diminishes among males when the urge to mate peaks in winter. This boldness may explain the behavior of the octopus I had struggled with. With plenty of arms for grap pling, males appear to writhe in combat with females. Mating (bottom left) can take hours. In this case the male, on the left, has enveloped the female's mantle with his web. The third right arm of a male octopus has a modified end called a hectocotylus, which transfers sperm-carrying tubes called spermatophores. During mating the hectocotylus is inserted into the female's mantle cavity, and a spermatophore is attached near one of her oviducts. In her den a female stares out from beneath her nest (right), which contains as many as 80,000 eggs. Using a mucous secretion, she attaches them to the ceiling in strands of 150 to 200 eggs, each about the size and weight of a grain of rice. In another den, nascent eyes show through egg membranes (bottom middle). Hatchlings burst forth and head for the surface, where they will begin feeding on plank ton. If they survive to maturity, these specks of life will increase their weight by a hundred thou sand times. But the odds are against them; in areas with sta ble octopus populations, an av erage of only two offspring from a clutch make it to adulthood. Always on guard, the female aerates the eggs by shooting water through her siphon and removes bits of foreign matter with her arms. For six months or longer she perseveres, rarely if ever eating, and nearly always dies of starvation. James A. Cos grove, a biologist at the Royal British Columbia Museum in Victoria, examines a female who had just died (far right). Already, crabs and small fish were feeding on her eggs.