大象传媒

Hearts have adapted to do some truly amazing things. There are animals that can use tricks to repair their own damaged cardiac cells, and there are those that have found biochemical ways to protect their hearts from an extremely high-fat diet. But the crocodile uses its heart to do something a little more unexpected.

The croc has a heart that's fundamentally similar to ours, but with a twist. In mammals, like us, the heart is a four-chambered pump that sends the blood on two distinct circuits. The right side of the heart sends the blood to the lungs to pick up oxygen. The blood then returns to the left side of the heart, which dispatches it on a long-haul journey, delivering oxygen to cells all over the body. After the blood has dropped off its oxygen, it picks up carbon dioxide, the waste product of respiration, to take back to the lungs after a pit stop in the heart again. This is how our heart works and it's how the crocodile's heart works. But unlike us, the croc has an additional option. Crocodiles have an extra aorta leading from the heart. Whenever it wants, the croc can use this extra pipe to bypass its lungs and instead send blood straight to its stomach. The carbon dioxide in this blood is a key ingredient for the production of gastric acid. Pumping this blood directly to the stomach allows crocs to secrete this gastric acid 10 times faster than mammals, allowing it to quickly dissolve bones in the chunks of prey it swallows.

If we could send our blood elsewhere at will, what would we do with it?

Some birds boast the world’s most acute eyesight, and there is one crustacean that takes colour vision to the extreme, but some would argue that the best eyes in the animal kingdom belong to the chameleon.

Stare into the chameleon's eye and you will see many things that might surprise you. For a start, it's unblinking; it has a single cone-shaped eyelid that fuses to its eyeball, making a turret and leaving only a tiny slit exposing the pupil. Chameleons have terrific colour vision and can even see ultraviolet light. They have very high photoreceptor density and their visual acuity is far better than our own.

The most amazing thing about the chameleon's eye though, is that its other one might be doing something else altogether. When focusing on prey, like a juicy cricket, the chameleon uses binocular vision, just like we do. But when moving around, surveying its surroundings, the chameleon can use each eye independently and so scan 342 degrees around its head. It could spot a predator on one side of its body and simultaneously have spied an escape route on its other side. A chameleon could easily watch TV and Tweet about it at the same time.

In addition to its eyes, the chameleon is also famous for its colour-changing capabilities. But other members of the animal kingdom can do remarkable things with their skin too.

Melanin is one of the main pigments in our skin. It comes in a few forms, varying in hues from pinkish to brown. It is a pigment we share with our sister kingdom, the fungi. Our melanin protects us from the radiation of the sun, but some fungi have been found using it to protect them from the radiation at Chernobyl. Fungi are an ancient form of life. They have retained some of the characteristics that allowed them to flourish when Earth was much harsher, before we had a thicker atmosphere that could insulate us from more of the sun’s rays. This means that black fungi in particular wear their melanin like a radiation-repelling lead apron. Unlike us, who keep our melanin locked up inside our cells, they incorporate theirs into the cell wall. But what is even more incredible is that they don’t just survive phenomenal levels of radiation, they can also use it to make food, in a way similar to how plants photosynthesise. This fungus has been found living happily inside the melted down nuclear reactors of Chernobyl, making food from levels of radiation that would kill a human. If we had skin that could do that, we would at least have some comfort food for the nuclear apocalypse.