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.
Photo Credit: Alaska SeaLife Center
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.
Octopi reproduction is really quite interesting. Males have a specially adapted arm, called a hectocotylus, which they use to transfer sperm packets called spermatorphores into to a female's mantle cavity. Octopi lead short, solitary lives of one to two years; the pair do not remain together, and males die within a few months of mating.
Photo credit: Mote Marine Lab & Aquarium
A female can store the sperm in her mantle until she is ready to fertilize and lay her eggs. A female may lay hundreds of thousands of eggs, which she anchors to a hard surface in a protected den.
After eggs are laid, she devotes the rest of her life to caring for them. She will guard the eggs and keep water circulating around them so that the developing offspring receive enough oxygen. The mother stops eating after her eggs are laid, and she will die soon after they hatch.
Newly-hatched octopi are called larvae, and will develop into hatchlings or fry. The newborn octopi, though tiny, are independant and require no more maternal care. Survival in the ocean is often a matter of luck, and very few of these offpspring will survive to adulthood— which is why so many eggs are laid to begin with.
A wondrous spectacle of nature
began unfolding on March 6 at the Alaska SeaLife Center: LuLu, a Giant Pacific Octopus,
has been tenderly guarding her brood of eggs, which she began
laying in March 2012. Now, over a year later, tiny hatchlings known as
paralarvae have begun to emerge, and the baby Octopuses are captivating visitors and staff.
LuLu laid eggs
throughout the spring of 2012 after an encounter the previous fall with Felix,
a male Giant Pacific Octopus. A female will lay up to
30,000 eggs only once in her lifetime, and she will brood and guard the eggs until
they hatch. A male may mate with several females but will
expire following this reproductive period. Lulu's lifespan will end when the last of her eggs hatch.
Photo Credit: Alaska SeaLife Center
"LuLu is not feeding at this time but continues to groom and fan the eggs
as attentive Octopus mothers do in this final reproductive phase of their
lives," said Richard Hocking, the Center’s aquarium curator.
While other Octopus species are
frequently raised from eggs in aquariums, that is not the case with the Giant
Pacific Octopus. Only once, in the mid-1980s, has a Giant Pacific Octopus been
successfully reared from egg to maturity in an aquarium. Giant Pacific Octopuses
are difficult to rear due to the delicate nature of the newly-emerged paralarvae
and their unique nutritional needs. To increase the odds of raising the
hatchlings to adulthood, aquarium staff are harvesting both wild and cultured
zooplankton to feed the paralarval Octopuses and have also constructed special
In the wild, the tiny hatchlings,
which are about the size of a grain of rice, swim toward the ocean surface and can spend
several weeks or even months drifting in the plankton-rich water until they are
large enough to hunt in the depths. Once they settle to the bottom, juveniles take
refuge in crevices and under rocks, where they are protected from predators while
they feed and mature. Octopuses eat crustaceans and mollusks along with other
bivalves, snails, fish and smaller Octopuses.
As adults, Giant Pacific Octopuses live in the cold waters
of the northern Pacific Ocean off the coasts of Canada, Alaska, Japan, and
Siberia at depths of over 200 feet (65 m).
Adults attain an arm span of up to 14 feet (4.3 m) and weigh about 33
pounds (15 kg). They are considered the
largest of all Octopus species. Little is known about these animals in the
wild, so they are not protected by international treaties.
Shortly after being put on exhibit at the California Academy of Sciences, this Caribbean Octopus vulgaris took up residence inside a glass bottle, on full view for adoring fans. Just as quickly, it moved back under a rock and started denning, and laying eggs. While eggs being laid in captivity is generally an exciting event, this particular species, like many but not all octopus, stops eating after it lays eggs and dies soon after they hatch which tends to put a damper on the joyous occasion. The biologist responsible for their care, Richard Ross, caught the hatching of the eggs from start to finish on film, and describes it as a waterfall flowing upwards toward the water's surface. Now, Ross faces the difficult task of trying to support thousands of tiny hatchlings. This species is "small egged" meaning it produces large numbers of very small planktonic 'paralarvae' which are notoriously difficult to feed and raise. The adult female and hatchlings will be on display for as long as possible in the Staff Picks area of Steinhart Aquarium at the California Academy of Sciences.
Yup, those little guys are what you think they are. Lots of baby octopuses! Video and stills taken by Rich Ross, California Academy of Sciences