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Red-backed Poison Frog (Ranitomeya reticulatus)

Red-backed Poison Frog (Ranitomeya reticulatus or Dendrobates reticaltus), Rio Napo rainforest area, Amazonian rainforest area, Loreto, Amazonia, Peru


It is the second-most toxic poison frog in the Ranitomeya genus, however, compared to other poison frogs it is moderately toxic. But the bright and characteristic colors and patterns alert possible predators: Do not touch me!


It is an arboreal and diurnal living frog, only 12-14 mm of length. The poison is not produced by the frogs themselves but for example from toxic fire ants and other insects which they feed on.


As you may know I use reduced flash and a paper tissue before the flash with frogs and almost no direct shot on the frog. So that's the reason why depth-of-field is not exactly what I am used to reach and remember: frogs are usually fast moving and following the frogs in the jungle is sometimes tricky: You are always on the risk to touch or sit or knee in ants, and that is definitely not very funny!!


Interesting facts: In a previous post I asked the question why some of the frogs in the neotropical rainforest are dependent on water but are not living directly in the water, as these little jewels will not do. Open water is too dangerous for the frogs. there are too many predators like fishes and dragonfly larvae wich will feed on the frogs and also tadpoles. So they choose another strategy for survival. Some species lay their eggs on leaves above the water surface to avoid direct killing by predators but they have still enough humidity not do dry out. Remember: Neotropical frogs have a sophisticated and very intensive and individual parental care. They do not produce masses of eggs and tadpoles to survive like most of the frogs do it out of the rainforest.


Another reason for the developing outside the water is the fact, that natural water resources are almost de-ionisied meaning there are no minerals and ions in it. Therefore there is an intense osmotic pressure on organism without a water-proof surface like frogs. The process of dilution will lead to an unilateral gradient with entrance of water in the organism and its cells and will destroy the tissues. Poison frogs and their eggs do not have a protection against this osmotic dilution. Some species solve this problem with establishing a system of eggs within a layer of spume/foam. Remember the last time when you have made egg white stiff? Some frogs do this with their legs. The result is a "stiffy" spume around the eggs and they are even protected against dehydration.


The skin of frogs is water-permeable, so they need water, but they do not live directly in the water or at the edges of little ponds. There are some African frogs which will change everyday their dried skin. That needs a lot of protein to rebuild this skin. In the neotropics there is not enough food available for doing this. Poison frog has choosen another way of protection. Humidity means constant challenge by bacteria and fungi to the thin frog's skin. To avoid infection and stabilize the skin they exude ... poison! The digestion process of these toxin by liver and kidney would be an extremely stress for these little frogs. Exuding by skin is much easier and they have even developped an effective protection mechanism against bacterial and fungal infection, detoxification of nutritiants, dehydration and several predators! This stretegy is so effective that they are almost not be hunted (however there are some snakes which were some kind of immune against the poison), they are allowed to live also diurnal and must not hide themselves due to the warning colors. And still: there are no masses of these frogs in the rainforest as it might be expected after installation of this sophisticated protection mechanism. The reason is again as I previously pointed out. There is not much food resources available.

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Taken on March 12, 2011