Golfodulcean Poison Frog
(Phyllobates Vittatus)
by Judit (Resident Biologist from the University of Cambridge)
After walking for about an hour in the rainforest and finally arriving to our destination, Golfo Dulce Retreat’s beautiful waterfall, the last thing on my mind was to hope to find one of the most unique, endemic animals of Golfo Dulce under the wet logs and rocks near the water. Whilst most other frog species found around the retreat are nocturnal, the Golfodulcean Poison Frogs (Phyllobates Vittatus), albeit a bit more shy, are diurnal (active during the day), so they can be spotted quite often on our hikes near water. The small frog is just 3cm long and has a deep, almost glittery black back, and green legs. The latin name of the species vittatus (meaning striped), comes from the two distinctive orange stripes going along the top of the body. The vivid colours of the poison dart frogs (Dendrobatidae) is an evolutionary adaptation called aposematism, which serves as a warning signal to predators about toxicity.
Golfodulcean Poison Frog (Phyllobates Vittatus)
The common name of the family comes from the fact that the indigenous people of Costa Rica and the Americas in general used to dip the tips of darts in the poison of these frogs, which would remain potent to up to a year. Although the Golfodulcean Poison Frog is only the fourth most toxic frog in its genus, the most toxic frog in the same genus is in fact the most poisonous frog in the world. The golden poison frog measures a mere two inches but has enough poison to kill 10 people. Perhaps quite counterintuitively, Phyllobates do not produce their own poison but instead they obtain their neurotoxin, batrachotxin (BTX) from a specialised arthropod-rich diet (melyrid beetles). This is underpinned by the fact that individuals raised in captivity are much less poisonous or not poisonous at all.
Golfodulcean Poison Frog (Phyllobates Vittatus)
Even though predators like the snake Leimadophis epinephelus can withstand the poison of Phyllobates, BTX is still one of the most potent toxic alkaloids on earth, causing heart arrhythmia, paralysis and cardiac failure. Whilst other poison dart frogs utilise a variety of toxic alkaloids, BTX is uniquely found in Phyllobates in neotropical frogs. You may wonder how this tiny frog is not poisoned by having such a high concentration of this potent toxin under its skin. To understand this, we must have a brief look at how the predators that make the mistake of tasting this frog are poisoned. Paralysis is achieved by BTX permanently binding to sodium channels in the predators’ nerve cells, interfering with the normal nervous response. Phyllobates seem to have evolved channels that are resistant to BTX but remain sensitive to other similar neurotoxins to which the frogs are not exposed to naturally.
Golfodulcean Poison Frog (Phyllobates Vittatus)
The IUCN lists this iconic frog of the Golfo Dulce region in Costa Rica as endangered, with much more research needed to understand the frog itself and the challenges it faces. Here at Golfo Dulce Retreat, we are privileged to have a healthy population of Phyllobates vittatus thriving near our waterfall, and we work closely with the Herpetology Programme Coordinator at Osa Conservation, a nonprofit organization dedicated to protecting local biodiversity of the Osa, in order to monitor our resident frog population (read more about their visit to Golfo Dulce Retreat in our blog section with a link below).
The Golfodulcean Poison Frog perfectly demonstrates that Golfo Dulce’s biome is extremely rare and fragile in the world, containing about 50% of the biodiversity of Costa Rica. The best way to experience this unique place is to come and see it with your own eyes…
Further reading on this topic:
Jungle Blogs: In search of the endangered frog
Rainforest Excursions: Waterfall Expedition