Something extraordinary is happening about 80 miles off the central coast of California: Thousands of pearl octopuses have come together for what scientists call an octopus garden. Researchers discovered the garden in 2018 but didn’t know why the cephalopods were gathering there. Now they have a theory: This area, on the side of an extinct underwater volcano, is an ideal place for the octopuses to mate and nest because it's warmer waters help the octopuses’ eggs hatch faster and help more baby octopuses survive longer. That’s all part of a new study from the Monterey Bay Aquarium Research Institute.
James Barry is a co-author of the study and a marine ecologist with the institute. He says it was startling when all the octopuses came into view of the researchers’ small submersible. “As they zoomed in to get a good close of the octopus, they saw this shimmering water that they hadn't noticed until they looked close. That shimmering water indicates warm springs that are bathing these nesting mothers.”
He explains that most octopuses breed in whatever temperature of water they live in. And for these creatures who live on the seabed, they glue their eggs to a rocky spot, and mothers tend to them for however long it takes to brood them.
“In shallow warm waters, that might be just days to weeks. When you get into cold waters, it's a different ball game altogether. … It's dark, it's deep, high pressure. The incubation times for deep-sea octopuses are on the scale of years, not weeks.”
He continues, “And these octopus [sic], we think have figured a way to short-circuit the system a bit, putting their eggs in these warm springs, where their metabolic rates will increase the rate of development.”
After hatching, the newborns struggle to get out from beneath their moms, while predators like anemones, shrimp, and snails are in the area. Some hatchlings swim away into the darkness and disappear, then decades later migrate back as adults.
Barry says octopuses usually live for 10-15 years, and one-third of that is spent breeding. However, scientists are trying to figure out their precise lifespan.
Are these sea creatures highly intelligent? “We don't know for sure. They definitely protect their young. … They'll repel disturbance, although we can get quite close to them, even within just a few inches, they don't seem to mind,” he explains. “But if we touch them, they immediately respond. And they're thinking about things and taking care of their young. So I want to think they're pretty smart. But that's another mystery. There are plenty of mysteries remaining, I guess.”