Sunday, August 14, 2011

Species Spotlights: Poison frogs and Glass frogs

Epipedobates tricolor | Phantasmal poison frog (Morispunga morph) Male transporting tadpoles.
Frogs are among the most diverse groups of vertebrates. They occur globally from the tropics to the sub-arctic regions, and in just about every conceivable habitat, one can find a frog species that has specialized to live there. Despite this diversity, it is generally easy to tell a frog from any other type of animal. Thanks, in part, to the absence of a tail like most other critters.

Due to the range of unique requirements these habitats demand of frogs, each species has specialized behaviors and/or characters and some of these specializations are quite spectacular.

Today, we are featuring two species which possess unique, prominent physical attributes. First, and one of the author's favorites is the Phantasmal poison frog | Epipidobates tricolor, which has been living, breeding, singing and hopping around the Fuqua Conservatory since 1995. Most poison frogs (family: dendrobatidae) have brilliant colors, which almost make them look fake. This trait is described as aposematic coloration, a terms that means the bold colors serve as warnings to potential predators. In the wild, many of these frogs contain enough toxin in the granular glands of their skin to disable or kill would-be predators. Most poison frogs are not lethal to humans, but many of them could at least ruin your day.

Some poison frogs, like the Phantasmal poison frogs lay their eggs terrestrially, where the male parent guards the eggs until they hatch. After the eggs hatch, he approaches the tadpoles, which then wiggle up his back. Once all the tadpoles are in place, he transports them to a puddle of his choosing (see picture). That is quite a commitment for a frog, as most species abandon the eggs immediately after fertilization and leave them to develop on their own. Once deposited into the water, the male has concluded his responsibilities until next time.

Cochranella granulosa | Ranita De Crista, gravid female, looking in at GI tract and eggs

The second species is a Glass frog | Cochranella granulosa (family: centrolenidae), which is not currently on display, but we are working with in one of our frog labs. When you look at the picture, you can see why they are called glass frogs—the skin on their ventral surface is transparent, allowing you to look right through the frog. I am not familiar with any theories suggesting why their skin is transparent, but it sure is easy to tell if they have eaten anything recently.