The Bam-Bam Frog
The bam-bam frog, Bombina Bambam, is closely related to the European yellow-bellied toad, and is found most commonly in southern Europe. Except for the crab-eating frog, Fejervarya cancrivora, it is the only known modern amphibian which can live in saltwater. However, the crab-eating frog can only sustain short excursion into ocean waters, whereas the bam-bam frog spends the entirety of its life-cycle in the salty marches found on the Mediterranean shore. But its uncommon habitat is not the most striking feature of this marvelous creature.
The Mediterranean marshes are the ideal nesting places for a huge number of birds, and also a preferred spawning ground for fish, crustaceans, and other marine animals. As such, it is an extremely rich environment, abundant not only in food, but also predators. To be able to survive in such a competitive landscape, the bam-bam frog has pushed the characteristics of his ancestors to the limit.
Frogs are known for their well-developed hind legs, and the ensuing jumping power. In the bam-bam frog, however, this feature has been polished to its peak. The hind legs of the bam-bam frog make up as much as 90% of its total body mass, and allow the frog to break the sound barrier. The maximum velocity of a jumping bam-bam frog measured to this date is 398 m/s (1433 km/h or 888 mph). The loud “bang” produced when the frog breaks the sound barrier also gave it its name. This immense burst of speed, however, has two draw-backs, which evolution has addressed rather elegantly.
The sudden burst of speed, which allows the bam-bam frog to accelerate from zero to the speed of sound in a few milliseconds, puts a tremendous strain on its muscles, and its body is heavily compressed by the air in front of it. At the same time, remaining in mid-air exposes it to the avian predators that can be found in abundance in its habitat. To deal with this, the frog has developed a number of mechanisms.
First, in addition to an extremely stream-lined body, bam-bam frogs have a much thicker layer of mucus on their skin than other amphibians, and their secretions have a much higher viscosity than that of related species. Second, the bam-bam frog has a loose flap of skin on its back.
Under normal circumstances, the excess skin is held together by the mucus. However, when the frog jumps, its muscles release a huge amount of lactic acid to compensate for the effort. This acid, in turn, liquefies the mucus. The liquefied mucus allows the frog to endure the rapid acceleration by absorbing the brunt of the compression. As the mucus is stripped away by the air, the skin flap becomes loose, and unfolds like a parachute, slowing down the animal. This ensures that the frog can jump in a relatively small angle without excessive risk of collision, which allows it to reduce the time it spends defenseless in mid-air. This has caused the bam-bam frog to be known by another name, the “paratroopers”.
Nonetheless, it can happen that frogs jump straight up, in which case they are easy prey for seagulls and other birds while the float gently back to the ground. In Camargue, France, seagulls are known to follow herds of wild horses, waiting until the mammals stumble upon a cluster of bam-bam frogs, and then feasting on the stray frogs who have miscalculated the angle of their jump. It has also been observed on numerous occasions that the loud noises of a startled group of bam-bam frogs can attract predators from miles away.
Recent studies suggest that in certain places, land and air predators seem to collaborate in capturing the amphibians. Since the frog is less likely to jump when there are birds in the air, snakes have been observed to hunt the frogs more intensely when there are seagulls or other predators flying above. Whether this collaboration is intentional or merely coincidental has yet to be determined.