
Antarctica's hostile environment makes it an incredibly challenging place for humans to work -- which is why researchers have enlisted the help of seals. Scientists from the Seal Mammal Research Unit at St Andrews University in Scotland have attached small devices to seals, which collect data year-round.

Antarctica is the world's fifth-largest continent and 98% of it is covered in ice. The inhospitable climate means there are no permanent human inhabitants -- but it's home to millions of seals, 20 million penguins, and countless seabirds.

In 2014, seals were tagged in the Amundsen Sea in West Antarctica, to gather more data about the rapidly melting Pine Island Glacier. Researchers tagged 14 seals in this first trip -- seven Weddell seals and seven elephant seals -- with smartphone-sized devices to track data on depth, temperature and salinity of the water.

These seal species were chosen because of the extreme depths they swim to while hunting. Weddell seals like this one, which wasn't involved in the research, can weigh up to 1,100 pounds, and dive to depths of up to 2,300 feet in search of prey -- mainly fish from the lower layers of the ocean, along with squid and octopus.

Named for the trunk-like noses of adult males, southern elephant seals are excellent divers that have been known to swim more than 5,000 feet below the surface. Storing extra oxygen in their muscles, elephant seals have adapted to spend up to two hours underwater without air.

In Antarctica, seals have no land predators, making it easy for scientists to approach them and tag them. For these seals, their main threats are in the water -- mainly orcas (known as killer whales) and larger seals.

Antarctica has 90% of the world's ice. Melting ice causes sea levels to rise. "Calving" is when icebergs break off from a glacier, which can cause huge parts of the ice sheet to collapse.

Between 1992 and 2017, the continent lost around 2.7 trillion tons of ice. Climate change in Antarctica will have a knock-on effect around the world. For some of the animals that live there, it could be catastrophic: a recent study suggests the emperor penguin population may be reduced by 50%.

After the first tagging trip in 2014, the team tagged seals in the Amundsen Sea again in 2019 and 2020, and are planning a trip for 2022. Pine Island Glacier and Thwaites Glacier, both located in the Amundsen Sea, are rapidly melting -- this data could help scientists better understand why, and more accurately predict environmental changes such as rising sea levels.