Have you ever seen a picture of two otters floating on their backs, holding each other’s paws? If you have, you might have wondered why they do that. Well, it turns out that otters have a very good reason for this adorable behavior: it helps them survive. Otters are semi-aquatic mammals that live in rivers, lakes, and coastal waters. They are very social animals that form groups called rafts, which can consist of a few individuals or up to a hundred. Otters often rest and sleep while floating on the water surface, but they face some challenges in doing so.   First, otters are warm-blooded and…