You are probably well aware of the life cycle of most frogs. They lay their eggs in water and when the tadpoles hatch they are on their own with no parental intervention. The lucky few will develop through this larval stage in to frogs. Yet there are a few South American species, such as the Mimic poison frog (above) which do things a little differently. They carry their tadpoles about on their backs.
The strawberry poison dart frog,
Dendrobates pumilio, (above and below) is transporting her tadpoles to somewhere she has chosen for its relative safety. This is not, of course, something which happens until the tadpoles fully develop but it is a vital element in the process of ensuring the next generation has the greatest chance of survival in to adulthood. These species usually live near water which flows too fast for spawn and newly hatched tadpoles to survive without being swept away.
So the frogs had to develop a system that ensured the tadpoles are as safe as they can be. The female deposits her eggs in a cluster of jelly under leaves on the forest floor. Some species will dig small burrows where the soil is moist enough so the eggs will not dry out. The male fertilizes them and then watches over the eggs until they hatch. Above you can see the eggs of the splash-back poison frog (
Ranitomeya variabilis).
Once they hatch the tadpoles will wriggle on to the back of the male or female (this depends on the species) and they are taken to a place of greater safety. For some species (like the three-striped poison frog,
Ameerega trivittata, above) this will be the local pool or water filled crevice but for the poison-arrow frogs such as the Panama (
Colostethus panamensis, below) and others, this involves something of a climb.
Once the tiny tadpoles are on board, the female climbs among the forest canopy. She takes them to a bromeliad that she has previously chosen as their new home. A bromeliad is a flowering plant which is able to store water in a structure formed by their tightly-overlapping leaf bases (think of the leaves on top of a pineapple). She pops the tadpoles one by one in to a separate pool created by these closely bound leaves. Altogether from the forest floor to the canopy, the journey can take several days.
Once they are in their miniscule domain the tadpoles are hopefully safe from predators and can develop in peace. They will eat algae in the water as well as any mosquito larvae they can find in their little pool. However, to ensure that getting enough to eat is not left to chance the female will come back and do something quite extraordinary.
She will return to her brood and in each of the pools she will lay an unfertilized egg which her ravenous offspring will devour. She will do this again and again over the next six to eight weeks until the tadpoles have undergone metamorphosis in to tiny versions of herself and are ready to leave their pool and brave the outside world and look after themselves.
Parental care depends on the species. For example, with the green-and-black poison dart frog, above, it is the male that does the carrying in to the canopy. He deposits the tadpoles and that, for him, is job over in terms of food. He does, however, stand guard over them while they develop.
This kind of behavior is not reserved to a few endangered species. The rainforest rocketfrog (
Silverstoneia flotator) above is very common in Costa Rica and Panama. It, like these other remarkable species, carries its tadpoles on its back.
Yet some species take this trait to perhaps its natural extreme. The Golden dart-poison frog (
Colostethus beebei, above), is a small brilliantly colored tree frog that spends its entire life-cycle inside the micro-ecosystem of the cloud forest's bromeliads. It cuts out that long trip up the trees, so why not.
First Image Credit Flickr User leeinhisroom
