By Ella Davies
Earth News reporter
The attack was caught on camera
A spectacled caiman attacked wildlife presenter Steve Backshall during filming for the BBC in Argentina.
Backshall was looking for yellow anacondas as he waded through wetlands but was taken by surprise by the crocodilian reptile.
The presenter was treated for puncture wounds to his calf before completing filming.
The incident was caught on camera by crew filming for the current series of CBBC's Deadly 60.
Presenter Steve Backshall witnessed first-hand the powerful bite of the spectacled caiman when he surprised one in the marshes of northern Argentina, close to the border with Paraguay.
Filming for the children's television series Deadly 60, the wildlife presenter's mission for the day was to find yellow anacondas, one of the largest species of snake.
The film crew were travelling by horseback, searching for snakes from a safe height.
As they traversed the marshes, one of their horses reacted to something in the water.
Steve Backshall's injuries
Video footage captured the moment when Backshall investigated what had caused the animal's panic.
"I jumped down into the water to try and catch it, and waded around in the muddy water trying to find it. Suddenly, my foot hit what felt like a log lying on the bottom of the swamp," he told the BBC.
The caiman struck the wildlife presenter in the left leg, tearing his trousers and puncturing his flesh.
"It was purely acting in defence, and trying to drive me away, and made no attempt to follow up the attack," he said, confirming reports that spectacled caiman are not known to attack unprovoked.
"However, it left a series of deep gashes running down my calf, which were pretty gory looking," the presenter added.
The crew immediately radioed for back-up and Backshall was taken to the nearest medical clinic for stitches, anti-inflammatories and antibiotics.
"This is the biggest thing I've ever been bitten by - well, apart from my sister's horse when I was a kid!" he said.
Backshall and the crew were able to complete filming after a short break for recuperation.
Spectacled caiman are the most common member of the crocodilian family, found from Peru and Brazil in the south to Mexico in the north.
They are named for the bony ridge that appears to join their eyes like a pair of spectacles.
Adults can reach a maximum of 3m in length and have a varied diet, feeding on fish, crustaceans, amphibians, reptiles and water birds.
Find out whether the spectacled caiman makes it on to the Deadly 60 list on CBBC at 1715 GMT, Thursday November 10.