As many as 20,000 octopuses congregate in a deep sea ‘Octopus Garden,’ strewn like pearls on the seafloor off the coast of California. The adult cephalopods are about the size of grapefruits, and there are so many that it’s the largest known consortium of octopus on the planet. It wasn’t until a few years ago that anyone knew about what was hiding 80 miles southwest of Monterey.
Mother octopuses are here to protect their eggs, laying upside down so that scientists thought they appeared like iridescent pearls at first glance. That’s why researchers nicknamed them pearl octopus (Muusoctopus robustus).
An Octopus Garden in Deep Sea Hot Springs
First discovered in 2018, teams of scientists have now determined that gathering adult pearl octopuses can incubate their eggs much faster here. Previously unknown hydrothermal springs can reach 51 degrees Fahrenheit (11 degrees Celsius) in pockets among the rock crevices. Elsewhere, waters at the same depths are near freezing.
By staying in the warmer water, the eggs can fully incubate in under 2 years versus the typical 5-8+ years it would take in cooler water. By incubating the eggs so much faster, the mothers give their babies the best chance for survival. As with other octopuses, they die soon after reproducing. However, the mothers usually live long enough to see their eggs hatch.
Why Mother Octopuses Tend to Die After Eggs Hatch
In 2022, scientists learned more about why mother octopuses torture and eat themselves when their eggs are near hatching. There are multiple chemical changes and their optic glands produce bile acid components, sex hormones, and toxic precursors of cholesterol. (Which people also produce temporarily) Why all these changes happen remains unclear. But, since octopuses tend to eat each other, it may be the ultimate sacrifice. Their bodies push a “self destruct button” to ensure the adults can’t eat their young.
When they die, the garden becomes a microcosm of creatures relying on the abundant food source left behind.
Today, the Monterey Bay National Marine Sanctuary protects the Octopus Garden, located near an extinct underwater volcano. They suspect many other sites like this one haven’t been discovered yet. Although nobody had seen this phenomenon a few years ago, scientists now think it may be widespread. Such an amazing discovery shows how little we know about the deep sea and why it’s critical to protect the oceans.
Related: Octopuses Live in Underwater Cities and Other Recent Surprises
Video by MBARI about the Octopus Garden:
