Posts tagged Frog Research
A Bird-Eating Frog is Discovered in Thailand – Research Update
Nov 20th
Hello, Frank Indiviglio here. In 1705, a painting of a Pink-toed Tarantula consuming a hummingbird, published in Maria S. Merian’s book on the insects of Suriname, aroused so much attention (and horror!) that all New World tarantulas are commonly termed “bird-eating spiders” to this day. It seems now that amphibian fanciers have their own dramatic bird-eater – Limnonectes megastomias, an aquatic frog recently described from 3 locations in Thailand.
An Aquatic Ambush Predator
The newly discovered frog is largely aquatic, and apparently catches birds that come to the water’s edge to drink – quite a unique feeding strategy for a frog (I once saw a surprising film of African Side-necked Turtles catching doves in this manner).
It is assisted in hunting by large (to 2 inch) “fangs” and a head that is disproportionately large for the body. The fangs are not true teeth but rather extensions of the jawbone, known as odontoid processes. The African Bullfrog and the South American Horned Frogs, known also for consuming vertebrates (and biting the hand that feeds them!), also sport odontoid processes. Insects and other frogs have also been recorded as prey.
Same Bodies, Larger Heads – Sexual Dimorphism
Interestingly, the heads and “teeth” of male Bird-eating Frogs grow much larger than those of females, despite similar body sizes. In certain other creatures (i.e. Barbour’s Map Turtles) this strategy allows the sexes to consume different diets and, it is theorized, avoid competition. Researchers also believe that the enlarged teeth are used in combat, as many males carry scars.
So Much to Discover
There are over 50 species classified in the genus Limnonectes- the new “bird-eater” appears most closely related to the Kuhl’s or Large-Headed Frog, L. Kuhlii, but little is known of its natural history (the photo attached is of a Kuhl’s frog).
This new species was first observed at the Sakaerat Environmental Research Station, an area that has been extensively studied for 40 years. The fact that such a large and unique frog was able to remain undiscovered in this area illustrates the untold opportunities open to those who wish to get out and look around in just about any habitat – recently a new centipede was discovered in NYC’s Central Park!
Further Reading
Another toothed amphibian behemoth, the African Bullfrog, also takes quite large prey…to read about a most unusual frog meal, please see my article An Appetite for Cobras.
Please write in with your questions and comments.
Thanks, until next time,
Frank Indiviglio
Limnonectes kuhlii image referenced from wikipedia and originally posted by W. Djatmiko
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Loading ...Research Notes – Hourglass Treefrogs (Dendropsophus ebraccatum) can choose either land or water as egg deposition sites
Aug 21st
Frogs are full of surprises when it comes to reproduction – there are species that incubate eggs below the skin of their backs and in the vocal sacs, while others carry them wrapped about their rear legs or construct foam nests on land. But in May of this year Boston University biologists working in Panama uncovered what may well be the oddest reproductive strategy of all – a frog that actively chooses to lay its eggs on either land or in water, depending upon the threats presented by each habitat. To date this is the only example of an egg that can hatch in either environment, and these frogs are the only vertebrates known to show such reproductive flexibility.
When breeding near shaded ponds, hourglass frogs lay their eggs on tree leaves overhanging the water (the tadpoles drop into the water upon hatching), thus avoiding fish and other aquatic predators. However, when utilizing ponds exposed to the sun, the majority of the frogs lay their eggs directly in the water, lest they dry out before hatching.
The “decision” is not governed genetically, because the same female frog will choose different egg laying sites when placed in a shaded or un-shaded pond.
Amphibians were the first group of vertebrates to evolve some independence from water. Biologists are now studying the hourglass frog to determine if its unique egg-laying flexibility might shed light on the evolution of terrestrial amphibian eggs.
Keep watching and studying your animals – amazing new discoveries are a real possibility. Please write in with your questions and observations. Thanks, until next time, Frank.
You can read more about the hourglass treefrog and its relatives at:
http://research.amnh.org/herpetology/amphibia/references.php?id=10041
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