What is it about frogs and popular culture? They seem to be a very fashionable small animal. Unlike insects or snakes, almost everybody likes frogs. It could be that there is not a natural aversion toward frogs because they will generally not bother you if you don’t bother them. Human’s evolutionary history does not include natural selection for avoidance of frogs like it does for avoidance of snakes. A frog jumping underfoot seen out of the corner of the eye catches attention. A snake slithering through the grass underfoot caught with the corner of the eye causes me to jump. Some princesses are even willing to kiss frogs (not a snake or a rat, but a frog, yes).
Some species of frogs have extremely potent toxin in their skins (the legendary poison dart frogs), but it is only dangerous if you eat or touch them. So, while we have a long evolutionary history of avoiding more aggressive toxic snakes and spiders, there is no similar danger from frogs through human history. Frogs have big eyes, and seem mostly un-threatening. Better yet, there are fantastically colored and shaped frogs that are fascinating to anybody who appreciates the natural world. Frog enthusiasts may not be as common as bird lovers, but there are plenty of them out there.
This attraction to frogs makes it all the more ironic that they are disappearing from under our very noses. If all the ticks and chiggers were disappearing, I would have difficulty working up as much emotion over it.
I asked Scott Connelly to send me pictures of frogs from the El Valle forests, and those that were dying from the disease in Panama. I had not seen many of these frogs when I was in Panama before because some are quite rare or active in other seasons. Still, I was curious about what was being lost. Scott is also deeply affected by the extinctions. He takes any chance he can to give public lectures using his extensive collection of photographs. He is surprised by how few people know about these frog extinctions, including other biologists. My experience parallels his on this score.
What Scott finds most amazing about these frogs is the astonishing diversity of form and function. For example reproductive strategies vary widely among species. Some frogs simply lay their eggs and leave, others care for the young. Male poison dart frogs of some species keep the eggs they fertilize on leaves wet by bringing water from nearby pools or tree holes. When the eggs hatch these males then transport the tadpoles on their backs to a suitable small pool and release them there to mature. Some frog species live in trees, others only on the ground. They all have different diets or other variations in their way of life.
Bufo coniferous is the green climbing toad found in El Valle. The adult looks like a typical warty (but attractive) greenish toad, but as a juvenile, it has brilliant red dots on its “warts”. Another member of the same genus, Bufo haematiticus is the blackbelly toad. This toad is light tan or grey on top and dark brown on bottom, with an attractive mottling of dark and light brown on the inside of its legs. It is thought to be abundant and not in much threat of extinction, but the chytrid was recently found to infect this species in high altitude areas.
Then there is Cochranella euknemos, the San Jose chochran frog. It is a pleasing, small, light green frog with all black eyes and a body covered with tiny neon yellow dots. This frog lives near streams in the vegetation and its populations are declining according to the Global Amphibian Assessment.
And there are more- Eleutherodactylus musous is a small, green, splotched frog that has protrusions of green and brown all over its body, and looks more like a clump of moss than a frog. Up to now this adaptation has aided the species survival because the camouflage helps it escape predation. This adaptation will do it no good against the chytrid. This frog only lives in the mountains of Panama and will probably go extinct from the disease. One cousin of this frog, Eleutherodactylus bufoniformis, the rusty robber frog, is an inch long round bodied animal that lies very flat to the ground. It has a splotchy skin that makes it look like a rock in the bottom of the stream or in the forest where it sits completely camouflaged.
There are even more colorful frogs. Rana warszewitchii, the brilliant forest frog, lives close to streams in forested areas and its tadpoles develop in the streams. It has a short trilled soft call. This forest frog is slender and brown with bright green splotches on its back, a yellow stripe in its groin and two bright yellow spots on the backs of its upper hind legs. One side of the bottom of each back leg is brown with black spots and the other side is pinkish red. It truly is a brilliant forest frog.
The coronated tree frog, Anotheca spinosa has striking strips of silver and pearl on its sides. It looks like a cross between a grey zebra and a triceratops dinosaur. It is three or four inches long, with bone spines on its neck; supposedly these spines are used to fight other male frogs to defend breeding holes high in the trees. After breeding, the female continues to return to the hole and lay additional eggs. The earlier batch of larvae consumes the eggs that the female lays. Presumably the purpose of the later eggs is to feed the earlier tadpoles.
Hemiphractus fasciatus is a 3 inch, buff, tan-colored, horned tree frog, with a flat five-pointed head. It has irregular splotchy bumps over its body. This frog looks more like a leaf than an animal. Initially scientists could not keep it alive in culture until they figured out it only eats other frogs. The habit of eating other frogs explains why it is only found in areas with high densities of other frogs. This frog does not need standing water to breed, although it is found in extremely humid forests, because the eggs are carried on the back of the female.
The jungle around Rio Maria is also the habitat of Dendrobates auratus, the green and black poison dart frog. These frogs have active males that sing a trilling note while perched on twigs or rocks above the ground. If multiple females are attracted they wrestle each other to mate with the male.
This is a personal favorite because we have some as family pets in aquaria at home and at work. We purchased frogs that were bred by a co-worker in the US, but unwittingly contributed to pet frog collection just by buying them. It is possible that much of the spread of the chytrid disease is caused by the pet trade in frogs. Furthermore, some species of frogs have been collected toward extinction for the pet and zoo trade. While this may be a way to preserve species, rarely are adequate records kept of collection location and breeding lines, so the genetics of the frogs is not preserved.
Dendrobates minutus, is the blue-bellied poison frog. This tiny frog is one of the few poison dart frogs that is not collected for the pet trade. It is a beautiful frog with alternating yellow and black stripes along its entire body. It has bright blue spots on its lower belly.
The above are only a few of the more than hundred species of frogs that could be found at El Valle. The main remaining species of frogs from this area now are in quarantined aquaria or have populations that also occur in lower, warmer elevation areas where the disease apparently is not fatal.
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