If you’ve visited the GSC in the last couple of weeks, it’s likely you’ve heard from a staff member or volunteer that our Giant Pacific Octopus (Enteroctopus dofleini) recently laid eggs. While this is very exciting news, it also means that the end of our female’s life cycle is drawing near.
Our Giant Pacific Octopus (GPO) has been here for about one year, weighing 9 lbs. at the time of her arrival. As of May 2018, she weighed 30 lbs. and stretched 6 ft. from arm tip to opposite arm tip. We can estimate from these numbers that at the time of laying eggs, she weighed around 40 lbs. Though ours is slightly below the average weight (around 50 lbs.) for GPOs, she’s very healthy. It’s always difficult to determine the age of an octopus, but we estimate her to be roughly 2.5 years old.
The average lifespan for a GPO is about 3 years, near the end of which they enter a stage referred to as senescence. Senescence occurs at the end of a mature octopus’ natural life; this is a roughly month-long period in which they mate. GPOs are one of many octopus species that are “semelparous,” meaning they reproduce once and then die. Salmon are another example of a marine species that does this. Senescence is characterized by several things, including loss of appetite, retraction of the skin around the eyes, laying and brooding of eggs (in females), uncoordinated movement or undirected activity (in males), and the appearance of white lesions on the body.
The process of laying eggs can be taxing on the female octopus, unfolding over the course of approximately a week. Eggs resemble grains of rice on strings, woven together to create a holdfast that attaches to a hard surface. The female octopus will lay eggs in her den (in which she’ll spend a good portion of her time) and prefers to attach them to an overhang. Brooding of the eggs occurs for five months to a year, during which time the female will aerate and clean them until her body succumbs to the stress of this process. During the brooding process, an octopus will start to lose her appetite and refuse food – all due to hormonal changes in the body. This leads her to becoming anorexic during the egg-guarding period – losing between 50-71% of her body weight – eventually leading to her death.
As all Giant Pacific Octopuses are wild-caught, it is unknown if the eggs are viable. Mating can occur early in life, with the female holding on to the spermatophores deposited by the male until she is mature and ready to use them. To date, only one successful rearing attempt has been recorded in captivity, occurring in 1986. This one male (who came from a population of 200 individuals from approximately 20,000 eggs) lived to 38 months. The process of keeping him alive was heavily labor intensive, requiring 6-8 hours per day for feeding and fastidious cleaning during the first 9 months of his care.
As for us, we’re excited for this opportunity to learn more about how Giant Pacific Octopus females behave while caring for their eggs and will be recording our observations extensively. Though we are not likely to have viable eggs, we’re excited to share this unique stage with all of you as the Greensboro Science Center experiences our first female octopus’ life cycle completion. Please feel free to find a volunteer or staff member during your next visit to ask questions. We look forward to seeing you.
Source: AZA Aquatic Invertebrate Taxon Advisory Group (AITAG) (2014). Giant Pacific Octopus (Enteroctopus dofleini) Care Manual. Association of Zoos and Aquariums, Silver Spring, MD.