THEY CAN LEARN

In the 1950s, US biologist Eugenie Clark first showed that sharks can be trained using food rewards, just like lots of other animals. More recently, researchers in the Bahamas taught captive lemon sharks to press a target with their snout in return for food (image of lemon shark on previous page). When sharks were kept with others that already knew what to do, they learned the task faster than when they were left to figure things out for themselves. This kind of social learning is another important aspect of animal intelligence. Other studies have shown that young lemon sharks prefer to hang out in gangs with other sharks they already know. It’s not yet known if they simply distinguish between familiar versus unfamiliar sharks, or if they recognise individuals.

LEFT: Marine biologist Eugenie Clark, seen here examining deep-sea sharks, was the first to show that sharks can be trained using food BELOW LEFT: Studies on manta rays suggest they may be self-aware, yet it’s likely that the fishy world contains more...