After being tended by their mother for almost a year, thousands of Giant Pacific Octopus eggs are beginning to hatch at the Alaska SeaLife Center (ASLC).
The eggs were laid by Gilligan, the ASLC’s eldest female Giant Pacific Octopus, beginning in May 2017. For the past year, Gilligan guarded her eggs, blew water over them, and groomed them to remove algae. About two weeks ago, aquarists noticed tiny Octopus babies – each about the size of a pea - floating in the tank.
The eggs are expected to hatch by the end of May, with about a hundred hatching so far. Each Octopus hatchling looks like a miniature adult, with all eight arms, sucker discs, and well-developed eyes. The babies swim by jet propulsion, just like adults.
As the babies rise to the surface of their tank, the staff collects them and places them in a rearing tank where they float and eat zooplankton.
Hatching and successfully rearing Giant Pacific Octopuses in an aquarium setting is extremely rare, with only one documented case of this species being reared to adulthood at the Seattle Aquarium in the 1980s. In the wild, the survival rate of hatchlings is about 1 percent. In an aquarium, the odds of survival are very low as the hatchlings are extremely delicate and have complex nutritional needs. This is ASLC’s third opportunity to raise Giant Pacific Octopus babies and staff remains hopeful as they begin rearing.
Giant Pacific Octopus mate only once in their three- to six-year lifespan. The male passes a spermatophore into the female’s mantle during mating. The female has up to 6 months to use it to fertilize her eggs. She then lays 20,000 to 80,000 eggs in long, braided strands that look like white, tear-shaped grape clusters. The process of laying the eggs can take about a month.
As for Gilligan, the hatching of her babies signals the end of her life. Because the female Octopus continuously guards her eggs for many months without hunting or feeding, she typically dies after her babies begin to hatch. Octopus hatchlings receive no maternal care, hence the low odds of survival to adulthood in the wild.
Giant Pacific Octopus are the largest of all Octopus species, with an adult weight of about 30 pounds and an arm span of about 14 feet. They feed on crabs, scallops, snails, clams, fish in the cold waters of the North Pacific Ocean to depths of 2,000 feet.