Observation of the Week, 2/18/18

Our Observation of the Week is this Yellow Treefrog that found a perch on the back of a Lethocerus Giant Water Bug, seen in Colombia by @estebanalzate! (Oh, and don’t forget the small insect on the bug’s back as well).

Insider info: I generally look for Observation of the Day possibilities by searching through recently faved observations, and when I saw the photo shown above, I thought it was a nice photo of a beautiful frog - and then I saw the Giant Water Bug! Thanks to our amazing users there are many stunning photos on iNaturalist that immediately grab your eye, but it’s also cool to come across images that continue to reveal beyond a first glance.

Esteban Alzante teaches herpetology and ecology at CES University in Medellín, Colombia, and says he’s been interested nature ever since he was a young boy in the 1980s, “when I was living in a very small town in the middle of the jungle and I could catch lizards, snakes, frogs and turtles in the backyard of my house and my mother would let me do that.” He’s currently studying frog ecology in Colombia, especially the antibacterial molecules found in the skin exudations of some frogs.

“We are looking for new molecules in 16 different species that belong to nine different families, these species had never been evaluated before, as there are many species in Colombia,” explains Esteban. “We found antibiotic activity in nine species, but just one of them has a more powerful activity than the commercial antibiotics.” He’s working on three separate papers, and is currently looking for a grant to identify the compounds in these secretions and submit his doctoral proposal.

Esteban takes his students into field with him, and he observed the above treefrog while on one of these outings:

...we found this puddle with hundreds and hundreds of Dendropsophus microcephalus Yellow Treefrogs, and they were in the reproductive period, it was so loud... and I found this little guy with his vocal sac inflated but when I was going take its picture it jumped on a branch, then i took the picture and that is when I realized that it had been on a bug's back.

Giant Water Bugs, members of the family Belostomatidae, are “true bugs,” meaning they’re part of the order Hemiptera, and have tube-like mouths for piercing and sucking. Often called “toe-biters” in the US, Giant Water Bugs are known to inflict a painful bite in self-defense (due to the injection of digestive enzymes), but the bite is not medically significant. In most genera, the female lays her eggs on the back of her male partner, and he will guard them, but in the genus Lethocerus, the female lays her eggs on vegetation near the water, which the male then guards. Lethocerus bugs are the largest of all true bugs, with some species growing to 12 cm (4.75 in) in length!

To give you a sense of scale, most Yellow Treefrogs reach about 25-31 mm (.98-1.2 in) in length, so this is a mighty large insect. The frogs range from Central America into the norther part of South America and onto some islands in the Caribbean, and are commonly seen. They are nocturnal, and come together at pools to breed. Eggs are laid on leaves overhanging the water, and tadpoles will drop from them when they hatch.

As Esteban (above, with a snake) continues his studies and field ventures, he’ll use iNaturalist to “share the biodiversity, mainly here in Colombia; we have hundreds of species that nobody knows, and my idea is do something for the people can identify them and to know as many species as I can.”

- by Tony Iwane (As English is not his first language, some of Esteban’s quotes have been lightly edited.)

- You wanted to hear what these frogs sound like, yes? They’re pretty loud.

- A Giant Water Bug takes down a garter snake in Arizona. Video here!

- Frog slime might be antiviral as well.

- Does the frog’s choice of perch remind anyone else of Han Solo’s similar maneuver with a Star Destroyer

Posted on February 18, 2018 11:59 PM by