Somebody's Teething!
Via Alaska SeaLife Center, which writes:
Let this video remind you that, at only an estimated two weeks old when he was admitted, this otter pup already has a strong jaw and sharp teeth growing in!
We know sea otters are incredibly adorable, but they are also animals with a strong bite force that can potentially be dangerous. When you spot a sea otter in the wild, always keep your distance and appreciate them from afar.