Black-Eyed Squid Glides Through Inky Waters With Thousands of Eggs Suspended From Its Arms Like Cape [Watch]

One of the squids known to brood their eggs -- the black-eyed squid -- was filmed swimming through the inky water. The spectacular sight was like no other as the thousands of eggs attached to its arms appeared like a cape.

Black-Eyed Squid Brooding Thousands of Eggs

Researchers spotted the black-eyed squid (Gonatus onyx) - one of the few squids known to brood their eggs - off the coast of Costa Rica in December. Mesmerizing footage shows the squid trailing its cargo of eggs like a long gown and flapping the fins protruding from its head to move through the water.

"The large egg mass is suspended from hooks on the squid's arms, and while carrying it for several months, the cephalopod will go without feeding," representatives of the Schmidt Ocean Institute, which organized the expedition, wrote in a post on Instagram.

While brooding squid are neutrally buoyant (i.e., they don't need to swim or float; instead, they can preserve energy by staying still), they are not extremely fast swimmers, which makes them potential prey for deep-diving marine mammals like whales and elephant seals. However, the advantages of mother care for the young squid exceed the danger of entanglement in food.

For a considerable amount of time, marine scientists believed that squids, including black-eyed squid, lay their eggs in groups on the seafloor and then let the eggs mature and hatch separately. Postdoctoral fellow Brad Seibel of the Monterey Bay Aquarium Research Institute (MBARI) challenged this notion in 2001, nevertheless. Seibal saw a black-eyed squid brooding an egg sack in Monterey Canyon off the coast of California through the lens of a remotely operated submarine.

Seibel and colleagues documented G's brooding habit in a 2005 study. Onyx females can transport up to 3,000 eggs over open water before the eggs hatch and the young leave the body. The squid may maintain their oxygen supply by pumping new water through the egg mass with their limbs.

Squids Don't Usually Brood

In order to breed, the majority of female squids either release their eggs in a gelatinous mass that floats and flows in open water or deposit their egg cases on the ocean floor. Squids typically die shortly after laying their eggs and do not typically brood them, per Chau Tu in 2016. So, capturing footage of a squid holding its eggs is extremely rare.

Only three species of squid are known to brood their eggs, and scientists don't know why. However, they believe it's to give the hatchlings a better chance of survival by keeping the eggs from being consumed by predators.

Scientists think that more deep-dwelling squids may be brooders due to these discoveries. There have been more reports of brooding habits in octopuses.

The value of venturing into deeper waters and learning about elusive species is demonstrated by documenting footage like the one featuring the squid and her eggs.

"The deep ocean is challenging to study, and we only get brief glimpses into the behaviors of deep-sea animals," MBARI researchers say. "Each observation logged by our ROVs provides another piece of the puzzle and helps improve our understanding of life in the deep."

Check out more news and information on the Giant Squid in Science Times.