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 Scientists on Wednesday described how the female of an octopus
species that dwells almost a mile below the sea surface spends about
4-1/2 years brooding her eggs, protecting them vigilantly until they
hatch while forgoing any food for herself.
It is the longest known egg-brooding period for any animal, they
wrote in the scientific journal PLOS ONE.
The scientists used a remote-controlled submarine to monitor the
deep-sea species, called Graneledone boreopacifica, off the coast of
central California.
They tracked one female, recognizable by its distinctive scars, that
clung to a vertical rock face near the floor of a canyon about 4,600
feet (1,400 meters) under the surface, keeping the roughly 160
translucent eggs free of debris and silt and chasing off predators.
This mother octopus never left the oblong-shaped eggs - which during
the brooding period grew from about the size of a blueberry to the
size of a grape - and was never seen eating anything. The octopus
progressively lost weight and its skin became pale and loose. The
researchers monitored the octopus during 18 dives over 53 months
from May 2007 to September 2011.
Bruce Robison, a deep sea ecologist at the Monterey Bay Aquarium
Research Institute in Moss Landing, California, said this species
exhibits an extremely powerful maternal instinct.
"It's extraordinary. It's amazing. We're still astonished ourselves
by what we saw," Robison said.
Most octopus females lay a single set of eggs in a lifetime and die
shortly after their offspring hatch. The newborn of this species are
no helpless babies. The long brooding period enables the hatchlings
to come out of their eggs uniquely capable of survival, emerging as
fully developed miniature adults able to capture small prey.
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At this tremendous depth, there is no sunlight - the only light
comes from bioluminescent sea creatures - and it is very cold - 37
degrees Fahrenheit (3 degrees Celsius). "It may seem nasty to us,
but it's home to them," Robison said.
During the brooding period, the mother octopus seemed to focus
exclusively on the welfare of the eggs.
"She was protecting her eggs from predators, and they are abundant.
There are fish and crabs and all sorts of critters that would love
to get in there and eat those eggs. So she was pushing them away
when they approached her," Robison said.
"She was also keeping the eggs free from sediment and was
ventilating them by pushing water across them for oxygen exchange.
She was taking care of them," Robison added.
This species measures about 16 inches (40 cm) long and is a pale
purple color with a mottled skin texture. It eats crabs, shrimp,
snails - "pretty near anything they can catch," Robison said.
(Reporting by Will Dunham; Editing by Cynthia Osterman)
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