Smart News | January 31, 2024

One species was found brooding eggs near low-temperature hydrothermal vents, a rare sight that could unlock new information on deep-sea cephalopods

an octopus with several of its tentacles facing out and draped over its mantle, or its body

an octopus with several of its tentacles facing out and draped over its mantle, or its body

A mother "Dorado" octopus, one of the newly announced species, protects her eggs some 3,000 meters under the ocean's surface. ROV SuBastian / Schmidt Ocean Institute under CC BY-NC-SA 4.0 DEED

Roughly two miles deep in the Pacific Ocean, on a dark and rocky outcrop near Costa Rica nicknamed El Dorado Hill, scientists from the Schmidt Ocean Institute observed the miracle of life—pinkish octopus hatchlings emerging from their warm, potato-shaped eggs.

These babies were the centerpiece of a two-part discovery announced earlier this month: Biologists found four new species of octopus, which have not yet been formally described, and examined an underwater ecosystem of hydrothermal vents, offering clues as to where more deep ocean species may be living.

“It was unexpected to find so many species of octopus in a small area, first, and second, at 3,000 meters depth,” Jorge Cortés-Núñez, a researcher at the University of Costa Rica and co-chief scientist with the Schmidt Ocean Institute, tells DW News.

a couple dozen brooding octopuses on the seafloor, lit by the ROV's light, curled into balls with their suckers facing out — Brooding mother octopuses curl up, facing their suckers outward in a defensive position. ROV SuBastian / Schmidt Ocean Institute under CC BY-NC-SA 4.0 DEED

One part of the discovery came last June, when researchers spotted the rare hatchery for the first time. Using a remotely operated vehicle named SuBastian, they identified two hydrothermal springs, two octopus nurseries and one skate nursery in the area. The second expedition, which occurred in December, verified for the team that these octopus nurseries seem to be active year-round.

Curled up on the black seafloor, defensively wrapped in their tentacles and facing sucker-side out, the cephalopod mothers had chosen this location strategically. Octopuses do not eat while brooding their eggs—a process that can sometimes take years in the cold, deep ocean. But by brooding near the region’s vast array of hydrothermal vents, which discharge water at around 54 degrees Fahrenheit, they seem to shorten the incubation period and give their offspring a better chance of survival.

a close-up on a nest of octopus eggs, with one small octopus breaking out and beginning to swim — An octopus hatchling emerges from its egg at Tengosed Seamount, off the Costa Rican coast. ROV SuBastian / Schmidt Ocean Institute under CC BY-NC-SA 4.0 DEED

For some scientists, the discovery of these hydrothermal habitats has been as exciting as finding the creatures they warmed. Only one other deep-sea octopus hatchery had ever been discovered before, off the Californian coast. The fact that cephalopods—which are usually solitary creatures—are being found congregating near vents, scientists say, could open new doors to octopus study and discovery.

“It was less than a decade ago that low-temperature hydrothermal venting was confirmed on ancient volcanoes away from mid-ocean ridges,” Beth Orcutt, a scientist at the Bigelow Laboratory for Ocean Sciences and a lead scientist aboard Schmidt Ocean Institute’s research vessel Falkor (too), says in a statement. “These sites are significantly difficult to find, since you cannot detect their signatures in the water column.”

a female researcher in a lab coat, glasses and a mask sits in a chair in front of a glass case with materials for processing samples — University of Costa Rica researcher Fiorella Vásquez studies a deep-sea octopus sample during the expedition. Conor Ashleigh / Schmidt Ocean Institute under CC BY-NC-SA 4.0 DEED

The new species spotted near the vents has been dubbed the “Dorado” octopus after the outcrop where it was found, making it the only one of the four to receive an unofficial nickname. Initial tests show the Dorado octopus shares many similarities with the pearl octopus (Muusoctopus robustus)—the most common species found among the vents off the Californian coast, reports Scientific American’s Ashley Balzer Vigil. The species displays short arms and small eyes.

Meanwhile, the other three species were found farther away from the vent ecosystem. Two of them also display traits indicative of the medium-sized octopuses that belong to the Muusoctopus genus, boasting two rows of suckers on their longer arms, no ink sacs and, notably, bigger eyes than the Dorado octopus.

a newly hatched octopus swims upward in a dark ocean — A new octopus hatchling swims up and away from its egg. ROV SuBastian / Schmidt Ocean Institute under CC BY-NC-SA 4.0 DEED

The fourth species, however, continues to puzzle the team. Its bumpy, pale skin and single row of suckers per arm are not easy-to-place traits, as Fiorella Vásquez and Janet Voight, the two lead researchers tasked with classifying the specimens, tell Scientific American.

In all, about 310 deep-sea specimens were collected across the June and December expeditions and taken to the Museum of Zoology at the University of Costa Rica. This marks one of the first times that all specimens from an octopus discovery are remaining within the Latin American country where they were found, rather than being transported to the United States or Europe, Popular Science’s Laura Baisas reports.

“The impact of the R/V Falkor (too) expeditions on understanding the deep Pacific waters of Costa Rica will last into the future and hopefully create awareness that evolves into policies to protect the deep sea of the country,” says Cortés-Núñez in the statement. “I hope that the expedition serves as an inspiration for new generations. We need more international collaborations to advance knowledge of our deep-sea heritage.”

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