After a massive iceberg broke away from Antarctica, it revealed a long-hidden world of creatures on the seafloor

Aylin WoodwardMar 25, 2021, 02:53 IST

The research vessel Polarstern in the gap between iceberg A74 (right) and Brunt Ice Shelf (left).Alfred-Wegener-Institut (AWI)/Ralph Timmermann

Last month, an iceberg the size of Los Angeles, called A74, broke off of Antarctica's Brunt Ice Shelf and floated away.
Researchers aboard the Polarstern vessel happened to be nearby, so they investigated the area of the seafloor that had been covered by the iceberg, half a mile down.
They found marine creatures that had been hidden for decades, including anemones, sea stars, sponges, marine worms, fish, and sea pigs. They also collected samples.
The researchers captured hours of video footage and thousands of underwater images. A selection of their most interesting photos are below.

The researchers aboard the Polarstern research vessel found themselves in the right place at the right time last month. They were sailing near Antarctica's northern rim when a giant iceberg broke off the continent.

Crew members of the Polarstern prepare to deploy an underwater camera system. Alfred Wegener Institute (AWI)/ E. Horvath

The researchers aboard the Polarstern research vessel found themselves in the right place at the right time last month. They were sailing near Antarctica's northern rim when a giant iceberg broke off the continent.

The iceberg, named A74, is about the size of Los Angeles, and more than 20 times the size of Manhattan. As it moved away from Antarctica, it revealed a part of the sea floor that hadn't seen sunlight in 50 years.

A view of the gap between iceberg A74 (right) and the Brunt Ice Shelf, where new ice has started to form. Alfred-Wegener-Institut (AWI)/Tim Kalvelage

The iceberg, named A74, is about the size of Los Angeles, and more than 20 times the size of Manhattan. As it moved away from Antarctica, it revealed a part of the sea floor that hadn't seen sunlight in 50 years.

The Polarstern crew deployed a camera instrument called the Ocean Floor Observation and Bathymetry System, or OFOBS.

Crew members of the Polarstern prepare to submerge the Ocean Floor Observation and Bathymetry System. Alfred Wegener Institute (AWI)/ George Brenneis

The OFOBS recorded five hours of footage and took thousands of photos.

Once OFOBS reached the sea floor, it spotted various creatures living among stones that had tumbled into the water from the ice shelf above.

A sea anemone attached to a stone under the Antarctic ice. Alfred-Wegener-Institut (AWI)/OFOBS-Team PS124

Most of the species were filter feeders, like sea sponges.

A sea sponge nearly a foot wide is affixed to a small seafloor stone. Alfred-Wegener-Institut (AWI)/OFOBS-Team PS124

According to Autun Purser, a member of the OFOBS team, the presence of these filter feeders wasn't a surprise. But some of the findings shocked his team.

A 1.5-foot-wide stone heavily populated by filter feeding animals, including large sponges. Alfred Wegener Institute (AWI)/OFOBS-PS124

Purser's team was startled to see many creatures swimming around, rather than staying stationary.

A marine worm leaves a spiral trail of poop on the sea floor. Alfred-Wegener-Institut (AWI)/OFOBS-Team PS124

The OFOBS spotted sea cucumbers, brittle sea stars, mollusks, worms, at least five fish species, and two types of octopus.

A stone housing a brittle sea star, or ophiuroid. The white curled features are the starfish's arms, raised to help it capture prey and food. Alfred-Wegener-Institut (AWI)/OFOBS-Team PS124

The OFOBS also glimpsed a cute type of sea cucumber called a sea pig.

Sea pigs, or holothurians, feed on organic material on the ocean floor. Alfred Wegener Institute/OFOBS-PS124

It's a bit of a mystery what, precisely, sustained this diverse, underwater ecosystem in the absence of sunlight. Most organic food stuffs and algae hang out in parts of the ocean where they have access to the light they need to survive.

An anemone surrounded by the poop trails of a long-departed marine worm. Alfred-Wegener-Institut (AWI)/OFOBS-Team PS124

It's a bit of a mystery what, precisely, sustained this diverse, underwater ecosystem in the absence of sunlight. Most organic food stuffs and algae hang out in parts of the ocean where they have access to the light they need to survive.

Purser said the team's observations show that marine ecosystems can be quite diverse and abundant, even if there's only a moderate amount of food available.

A view of the Weddell Swa between the Brunt Ice Shelf and the A74 iceberg that broke off the shelf in February 2021. Alfred Wegener Institute (AWI)/ Ralph Timmermann

This isn't the first time Antarctica has lost a giant iceberg, and it won't be the last.

A crack in the Brunt Ice Shelf that eventually birthed iceberg A74, as seen from the air on January 12, 2021. Andy Van Kints/British Antarctic Survey

Researchers aboard the Polarstern said icebergs the size of A74 slough off every decade or so.

A TerraSAR-X satellite image of the A74 iceberg, left, in the Weddell Sea of Antarctica as it breaks off from the Brunt Ice Shelf. TSX data © DLR 2021/ Courtesy of Alfred-Wegener-Institut (AWI)

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After a massive iceberg broke away from Antarctica, it revealed a long-hidden world of creatures on the seafloor

The researchers aboard the Polarstern research vessel found themselves in the right place at the right time last month. They were sailing near Antarctica's northern rim when a giant iceberg broke off the continent.

The iceberg, named A74, is about the size of Los Angeles, and more than 20 times the size of Manhattan. As it moved away from Antarctica, it revealed a part of the sea floor that hadn't seen sunlight in 50 years.

The Polarstern crew deployed a camera instrument called the Ocean Floor Observation and Bathymetry System, or OFOBS.

The OFOBS recorded five hours of footage and took thousands of photos.

Once OFOBS reached the sea floor, it spotted various creatures living among stones that had tumbled into the water from the ice shelf above.

Most of the species were filter feeders, like sea sponges.

According to Autun Purser, a member of the OFOBS team, the presence of these filter feeders wasn't a surprise. But some of the findings shocked his team.

Purser's team was startled to see many creatures swimming around, rather than staying stationary.

The OFOBS spotted sea cucumbers, brittle sea stars, mollusks, worms, at least five fish species, and two types of octopus.

The OFOBS also glimpsed a cute type of sea cucumber called a sea pig.

It's a bit of a mystery what, precisely, sustained this diverse, underwater ecosystem in the absence of sunlight. Most organic food stuffs and algae hang out in parts of the ocean where they have access to the light they need to survive.

Purser said the team's observations show that marine ecosystems can be quite diverse and abundant, even if there's only a moderate amount of food available.

This isn't the first time Antarctica has lost a giant iceberg, and it won't be the last.

Researchers aboard the Polarstern said icebergs the size of A74 slough off every decade or so.