Now we know why these incredible creatures gather in this and other warm springs underwater.
In a video narrated by Jim Barry, the author of this article, scientists from the Monterey Bay Aquarium Research Institute will take viewers on a trip to Davidson Seamount. Credit: (c) MBARI.
We explain in a brand new study that involves scientists from different fields why octopuses migrate toward the Octopus Garden. The Octopus Garden is both a breeding site and a nursery, where the octopus’ young develop faster than they should, giving them a better chance of survival in the cold, deep sea.
Octopus Garden: A Garden of Life
The female octopus will seek out cracks in the rocks, where warm water seeps. They guard their young there. These mothers are unable to eat because they rely on their energy reserves. They make the ultimate sacrifice to protect their offspring and die when their eggs hatch.
The Octopus Garden is located at the base of Davidson Seamount, about 80 miles (130 km) southwest of Monterey in California. It’s the largest of a few octopus nurseries that have been discovered recently in the Eastern Pacific. Many of them have been found near hydrothermal pools where warm water seeps up from the seafloor.
It is located near Davidson Seamount (an inactive volcano) off the Central California Coast. The Monterey Bay National Marine Sanctuary contains the Octopus Garden. Esri, GEBCO, DeLorme, NaturalVue
We wanted to find out what makes nesting octopuses so attractive in these environments.
We assembled geologists, engineers, and biologists to solve this mystery. Using Monterey Bay Aquarium Research Institute deep-sea robotics and sensors, we studied and mapped the Octopus Garden over several visits over three years. We were interested in the relationship between breeding success and thermal springs. Nearly 6,000 nests were found in a 6-acre (2-hectare) area. This suggests that more than 20,000 pearl octopuses inhabit this site.
A six-month time-lapse video of a grouping of nesting mothers opened a window to the dynamic lifestyle in the Octopus Gardens.
The Octopus Garden has a female pearl octopus who is brooding eggs. Credit: 2020 MBARI
We saw male octopuses approach and mate with females. We were delighted to see the hatchlings emerge, looking like miniatures of their mothers. We mourned for the mothers who had died and their young.
A different mother octopus quickly filled in the nests that became empty. At the Octopus Garden, we saw that no food was wasted. The dead octopus was a valuable food source for many scavengers like sea anemones or snails.
The warmer water accelerates embryo development.
Before hatching, a new generation of Octopuses must overcome two obstacles.
They must first develop from an egg into a hatchling. Initially, they are opaque eggs in the shape of sausages that are cemented to rocks. Over time, the tiny black eyes and eight arms become visible. Second, and equally important, the embryos must not succumb to external threats such as predators, infections, or injuries. The longer a source is incubated, the higher the chance that it will not hatch.
The photomosaic was created after surveys were conducted in the Octopus Garden using the MBARI remotely operated vehicle Doc Ricketts and the Low-Altitude Survey System Sensor Suite from the Seafloor Mapping Lab of Monterey Bay Aquarium Research Institute (MBARI). Researchers were able to estimate nest numbers and count nests using the photo. Credit: 2022 MBARI
Brood Periods are short for octopus species that live in shallow, warm waters. In the abyss, however, a different scenario is played out. Coldblooded animals such as octopuses are affected by temperatures near freezing. The longest known brood period of any animal is actually from a deep-sea species of octopus, Graneledone Pacifica. A mother will tend her nest for an amazing 4 1/2 years. A nursery of this species has been discovered off the coast of Canada.