Due date narrows for octopus mom
Over the last ten months the giant Pacific octopus LuLu, a resident of Alaska SeaLife Center, has proven to be an attentive mother to the hundreds, or thousands, of eggs she laid last spring. She’s sucking water in through her mantle, and blowing it over them, and fanning it to give them plenty of oxygen and keep the water circulating. Day in and out she’s hovering over these pearly white curtains of rice-like eggs that hang off separate threads like grapes, rarely leaving them to feed herself. She’s visibly losing weight in the process. Any approaching starfish or aquarium personnel she aggressively pushes away with her long arms. Large rocks that she picked up, and with which she had hoped to barricade herself and her eggs behind, lie scattered below her on the tank floor.
Meanwhile, scientists like ASLC Aquarium Curator Richard Hocking, and Aquarium Coordinator Jared Guthridge are carefully observing her behavior, and learning new things about the and reproductive cycle of this fascinating alien-like creature.
Guthridge will be responsible for rearing any eggs that may begin to hatch this spring. He confirmed the first signs of embryonic development on Oct. 21 when eyespots appeared inside several eggs. On Dec. 12, dark eyes and pigment spots appeared on the embryos. Given their past experience, the aquarium staff expects hatching to begin in about three or four months.
Each time they allow their giant Pacific octopuses to mate at the center they learn new things which are of interest to octopus researchers everywhere, and which could help them improve their care and rearing of young in the future. But it doesn’t happen often. The last time they successfully mated one which laid fertile eggs at ASLC, was nine years ago, when Aurora mated with J-1 in 2004. That mating, J-1’s subsequent post coital natural death, and Aurora’s brooding, and slow deterioration and death, as happens after eggs hatch, received intense national and worldwide media coverage.
The eggs hatched, but did not survive long enough in their special tanks to produce viable octopuses. Octopuses have never been successfully reared from the egg stage in an aquarium setting.
On Sept. 15, 2011, LuLu was introduced to an older, larger male named Felix, who was already living in the Denizens of the Deep exhibit and appeared to have entered senescence, meaning that he was nearing the end of his life, and was acting ready to mate. Seeing that Lulu was between three and four years old, and weighed about 46 pounds, they hoped that she was large enough or mature enough to mate. They mated as fascinated staff watched and videotaped their brief union in real time, and Felix was removed soon after so that LuLu would be more comfortable laying her eggs. He died not long after that.
From the previous mating experiment with Aurora and J-1 center staff had learned that it might be best to remove the male octopus from the female soon after mating, because Aurora did not lay eggs until after they finally removed J-1, he became aggressive toward her. Previous to that, a female octopus had killed the male with whom she had mated.
With Aurora, and again with LuLu, ASLC scientists have confirmed through their observations that a female giant Pacific octopus will retain its eggs inside her body until the time she feels is right to lay them.
What surprised them most about LuLu’s mating however was how long she managed to retain those eggs: from their mating on Sept. 15, 2011 until March 19, 2012 six months later. She continued laying eggs bit by bit over the next two months.
“This is interesting to us because of the six month delay between mating and egg laying, suggesting that if these eggs turn out to be viable, she delayed fertilization until some other criteria were met,” said Hocking. Those criteria could have to do with her age or physical maturity, the season, or even the water temperature, said Hocking. Their observations may demonstrate that a female giant Pacific octopus that is large enough to mate, but not yet fully mature, can hold the eggs inside until she is fully mature.
There is not enough adequate data available from giant Pacific octopus in the wild that are captured and studied, to prove their length of gamete egg retention, but since the sea life center aquarium scientists know all about LuLu, with whom she mated, and when, their observational data may interest the scientific community, said Hocking.
Because none of Aurora’s thousands of tiny hatchlings or octopus paralarvae survived in 2004, Guthridge believes they might increase their chances of survival by leaving some inside LuLu’s tank longer before removal, while rearing the remainder in separate holding tanks dedicated to the purpose, and modified differently for these small, mobile and delicate swimming organisms to avoid abrasions from contact with tank surfaces.
The paralarvae live in the water column feeding on plankton for several months until they settle to the bottom and find dens to occupy. They will be fed various foods, including live zooplankton harvested from their incoming seawater to approximate what these baby octopuses find in nature. They’re hopeful that a small number will reach the stage where they settle to a bottom dwelling life stage and care is easier, and that LuLu will continue to feed herself long enough to see her eggs hatched, before stopping eating altogether.
Alaska residents can visit the ASLC free of charge on Wednesdays throughout this month from 10 a.m. to 5 p.m.