“He approaches slowly.” Filmmakers built a robot otter and released it into the Alaskan sea. What it saw was astonishing

Tool use was once believed to be exclusive to humans, but plenty of animals have since been seen using objects to help them forage for food, clean themselves and create shelter.

One of these species is sea otters.

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While sea otters do eat fish, they prefer to eat clams, mussels and crabs. And as they spend most of their time floating in the water (even giving birth in it), they’ve had to come up with an ingenious solution to cracking open tough shells.

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So, to capture this incredible behaviour, filmmakers and scientists teamed up to create a robotic ‘Spy Sea Otter’ camera for the BBC TV series Spy in the Wild.

And when Spy Sea Otter is deployed in the Alaskan sea, it “approaches slowly and soon captures some of the closest and most intimate views possible”.

A distance of at least 60 feet (or five kayak lengths) is recommended if you encounter sea otters. However, with Spy Sea Otter, an otter quickly comes up to inspect it – and the spy seems to pass the test.

“Filming sea otters in Alaska was quite difficult,” explained Matthew Gordon, one of the producers of Spy in the Wild, in a Reddit thread in collaboration with broadcaster PBS.

“Not only did our spy creature have to be waterproof, but we had to be sometimes over 1km away and we had to deal with small icebergs interfering with our transmitter signals.”

Sea otters most commonly use rocks as anvils, resting it on their chest and cracking open shells against it. However, they have occasionally been observed using rocks as hammers.  

But what’s particularly special about sea otters is that they have specialised pouches of loose skin underneath their forearms. They often store a rock in these pouches, leading to the widespread belief that sea otters have a ‘favourite rock’ that they like to keep hold of.

However, it’s more likely that once they’ve found a particularly effective rock, it’s useful to keep hold of it, rather than diving to the seabed to find another.   

Top image: a screenshot from a video filmed using Spy Sea Otter. Credit: John Downer Productions/Getty