Can you imagine sitting over a nest of eggs and protecting it for four-and-a-half years without eating or sleeping at all? Sort of makes normal human child-rearing sound somewhat easier doesn’t it? Well, that’s apparently exactly what a deep-sea octopus was recently observed doing by researchers at the University of Rhode Island and the Monterey Bay Aquarium Research Institute.
The new observation means that the octopus species in question spends more time brooding its eggs than any other animal currently known. The behavior is of course common to all (or nearly all) octopus species — an octopus mother spending all of its time and energy keeping its eggs clean and guarding them from predators, until it literally dies from exhaustion. Four and a half years of that is pretty impressive when you think about it.
“This research demonstrates how little we know about life in the deep-sea and life generally,” noted Brad Seibel, a URI associate professor of biological sciences. “From shallow-living species we have developed limited and limiting ideas about the capabilities of animals.”
Previous work had suggested that the eggs of some deep-sea octopuses could take years to develop — something that this new work proves.
“While we predicted a long development time, our confidence in that prediction was not high and our result was still surprising.”
The press release provides more:
<blockquote>Every few months for the last 25 years, a team of Monterey Bay researchers led by Bruce Robison has performed surveys of deep-sea animals at a research site in the depths of Monterey Canyon that they call Midwater 1.
In May 2007, during one of these surveys, the researchers discovered a female octopus clinging to a rocky ledge just above the floor of the canyon, about 4,600 feet below the ocean surface. The octopus, a species known as Graneledone boreopacifica, had not been in this location during their previous dive at this site in April.
Over the next four-and-a-half years, the researchers dove at this same site 18 times. Each time, they found the same octopus, which they could identify by her distinctive scars, in the same place. As the years passed, her translucent eggs grew larger and the researchers could see young octopuses developing inside. Over the same period, the female gradually lost weight and her skin became loose and pale.
The researchers never saw the female leave her eggs or eat anything. She did not even show interest in small crabs and shrimp that crawled or swam by, as long as they did not bother her eggs.</blockquote>
A month after the last sighting of the brooding octopus in September 2011, the researchers returned to find the female gone, and nothing but the remains of egg capsules. “The rock face she had occupied held the tattered remnants of empty egg capsules.”
By the researchers count, at least 160 egged were being protected by the octopus.
A bit more background:
<blockquote>Most female octopuses lay only one set of eggs and die about the time that their eggs hatch. The eggs of Graneledone boreopacifica are tear-drop-shaped capsules the size of small olives. As the young develop inside the eggs, they require plenty of oxygen. This means that the female octopus must continuously bathe the eggs in fresh, oxygenated seawater and keep them from being covered with silt or debris. The female must also guard her eggs vigilantly to prevent them from being eaten by predators.
Because the young octopus spend so much time in their eggs, by the time they hatch they are fully capable of surviving on their own and hunting for small prey. In fact, the newborns of G. boreopacifica are larger and better developed than the hatchlings of any other octopus or squid.</blockquote>
“The ultimate fate of a brooding female octopus is inevitably death,” the researchers wrote, “but in this first example from the deep sea, brooding also confers an extension of adult life that greatly exceeds most projections of cephalopod longevity.”