大象传媒

Mudskippers are unusual fish. As they spend much of their life out of the sea, they can walk on land and breathe air. Rich mud flats exposed at low tide, like these in Japan, are the secret to mudskipper existence. Sunlight hitting the mud allows small plants and animals to flourish almost instantly, providing a rich food supply. Though food is easily come by, life on land becomes hard work when it comes to finding a mate. A mudskipper needs to get noticed, and does this by jumping as high as it can. Eyes on the top of the head allow him to keep a look out and spot any intruders, which are then fought off. Another issue for aquatic species on land is keeping moist. A smaller species of mudskipper deals with this problem by creating tunnels under the mud. The male digs out a u-shaped tunnel advertising his hard work with the spoil heap surrounding the entrance. As the tide comes in and out, the tunnel is flooded and requires constant attention to keep it open. At the far end of the tunnel is an air chamber whose walls are lined with eggs. The eggs get more oxygen from air than they would from water, but as it's cut off from the outside air, the male constantly has to swim back through the tunnel, take a gulp of air at the entrance, and return to the chamber to expel it and replenish the oxygen. It's hard work for a fish living on the land!