The chance rescue of a deep-sea octopus from a line trap off La Jolla gave researchers at Scripps Institution of Oceanography the unique opportunity to study the maternity cycle of a rare creature.
The female North Pacific bigeye octopus was recovered from a trap set for 200 to 250 meters. Deep-sea specimens are notoriously difficult to keep alive in captivity, yet this octopus went on to lay fertilized eggs at the Scripps Experimental Aquarium.
For the first time, researchers observed as baby octopuses from a deep-ocean species developed and hatched and witnessed the octopus’s behavior before and after she laid the eggs.
“Even though this species was discovered over a century ago, we didn’t know how long incubation would take or anything about its early life history. They’ve rarely been raised in captivity and there were no other known records of fertilized eggs,” said Adi Khen, a Scripps Oceanography graduate student and lead author of the study released Nov. 3 in the journal Ecology and Evolution.
Eye spots were noticed within the octopus eggs after four months. The female octopus demonstrated typical maternal behavior of constantly guarding the eggs, cleaning them with her suckers and blowing water on them.
Khen said the 10-month development period until all eggs finally hatched was a victory for science but bittersweet nonetheless. After five months caring for the eggs, the female octopus was found dead after having climbed out of the tank overnight.
At that point, Khen and colleagues took over caring for the eggs, aerating them with a turkey baster to simulate movement by the female’s arms and to prevent bacterial or fungal growth.
It is inevitable for brooding octopuses to die when their eggs hatch, but “I’d like to believe she trusted us and thought we had it handled,” Khen said.
The eggs hatched over the course of two and a half months. None in the first group survived, but later hatchlings did, being developed enough to eat the amphipods, frozen krill and fish fed to them. Several were donated to aquaria throughout California.
The specimens that did not survive were frozen, preserved and permanently housed in the Benthic Invertebrate Collection at Scripps Oceanography.
“Despite their loss, they can still contribute to science,” Khen said.
Study co-authors include Lillian McCormick, Christine Steinke, Greg Rouse, and Phil Zerofski, all from Scripps Oceanography.