Animal tails are usually round, but seahorses' are square-shaped. A 2015 study showed that this could enhance the fish's grip by increasing the surface area of the tail in contact with an object.

As the fish closes its mouth, the flap opens. Oxygen is extracted from the water as it passes over the gills. Other fishes have gill slits. Tails: Fish tails also take many shapes. A crescent ...

As the fish closes its mouth, the flap opens. Oxygen is extracted from the water as it passes over the gills. Other fishes have gill slits. Tails: Fish tails also take many shapes. A crescent ...