Posts Tagged ‘frogs’

I just got back from my most recent field excursion and am completely exhausted. But look, I am nevertheless providing you with things to read! The new species announcements have been piling up for a few months, so here is another roundup of recently discovered or described life forms on this lovely planet of ours.

  • A plethora of colourful, strange-looking creatures from Suriname
  • A tiny deep-water shark from around the Galapagos
  • The littlest chameleons! (Highlights: figures 6, 8, and 10.)
  • One that deserves a lot more publicity: an Amazonian fungus that can eat plastic, potentially helping to break down garbage in landfills
  • A keen-eared herpetologist discovers a new species of leopard frog right smack in NYC
  • Also re: urban New York wildlife, this post is an enjoyable read about engaging non-biologists in nature. There’s not an undescribed species found, but they do discover ants that, though widespread and abundant there, had not previously been documented in New York.

Enjoy! I will tell you all about the Hawaiian rainforest in a few days!

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(or at least the first to make headlines; I don’t actually pay that close attention)

The world’s smallest frogs—in fact, the world’s smallest vertebrates—are two newly described species from New Guinea, Paedophryne amauensis and P. swiftorum. What makes them particularly cool is that they are terrestrial, while the previous holders of the smallest vertebrate title were fish. It was thought that aquatic vertebrates could reach smaller size extremes because of buoyancy-related release from constraints. Apparently this is not so. Here’s the original article describing these two species and one of many media accounts.

Not a new species, but a new discovery about a known species: a Brazilian plant called Philcoxia minensis turns out to be carnivorous. It is unique in that it has underground leaves in addition to its normal leaves that capture and digest small nematode worms.

In cutesy scientific name news, just in time for the arrival of a certain baby of famous parents, entomologists named a species of horsefly Scaptia beyonceae, because its shiny golden abdomen is, as we like to say in the technical literature, “bootylicious”.

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ResearchBlogging.orgSometimes I think the biological literature needs more natural history reports. Sometimes I get to read such reports and I’m not sure that I wanted to know what they had to tell me.

To wit: there are two species of beetle, Epomis circumscriptus and E. dejeani, whose larvae eat frogs (and other amphibians). They do so in a rather unusual way: they don’t kill them and then chew them up, but rather attach to them like a leech and suck them dry. And they actively lure in their prey by twitching their antennae and mouthparts (in a manner that I assume mimics the movement of smaller insects like ants; at least, that’s what it looks like to me – see video S1 at this link). When the frog tries to chomp them—and frogs can move really fast—the beetle larva moves even faster and latches on to the  frog’s mouth or belly and just doesn’t let go. In fact, it has double-pronged mouthparts for doing so. The frog can’t get it off, and is just gradually sucked dry.

What is even more cool/horrifying is how resilient the beetles are. Many beetle larvae are soft-bodied; these, instead, are tough enough to endure the frog’s pawing at them and trying to swallow them. One, in fact, does get completely swallowed. And it stays alive, squirming in the frog’s belly for two hours, before the frog pukes it up. And then it eats the frog.

There’s a video of this (it’s video S4). I watched it twice in a row, and sat there with my mouth hanging open, unsure whether to shout “holy shit that’s cool!” or just whimper. I just watched it again and I still can’t decide.

Okay, deep breaths; serious science blogging time.

I am curious to know why the frogs (apparently) eventually stop trying to dislodge the larvae and just let themselves be drained. Are the larvae injecting them with some toxin (I’ve never heard of a beetle doing that)? Or just weakening them to the point where they can’t fight back? Or, in nature, do they usually drop off before the host dies?

Also, does this really constitute “role reversal” as the paper defines it? It seems to me that the beetle larvae are mimicking some other potential frog prey, and amphibians typically look for movement when hunting, whereas the larvae are only moving their mandibles and antennae. Although some of the frog species tested eat close relatives of Epomis beetles, perhaps this is not a case of a typical prey becoming a predator (if the ancestors of these two species are sit-and-wait predators that normally eat other creatures) but rather just of the origin of a new predatory behaviour. But right now there’s probably not enough information to evaluate either hypothesis, and regardless, I don’t mean to detract from this truly cool discovery. (Yes, I’ve come down on the side of amazement rather than horror in the end.)

Wizen, G., & Gasith, A. (2011). An Unprecedented Role Reversal: Ground Beetle Larvae (Coleoptera: Carabidae) Lure Amphibians and Prey upon Them PLoS ONE, 6 (9) DOI: 10.1371/journal.pone.0025161

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Pond withdrawal

The minor blog hiatus of the past two weeks was due to my defending my Master’s thesis. Take that, science!

This past week, I officially ended my habitat choice experiment (explained here). Yes, I continued this experiment virtually up to the day of my defence; don’t ask—like all experiments, it did not go smoothly. Anyways, I removed all the remaining fish—which will be used by other grad students for their own projects—from my ponds, took out the enclosures, washed them, and packed them away for some future scientist’s use. It was a little sad. But it was impressive to see how well those enclosures held up after more than a year exposed to the elements. What was even more impressive was how they became part of the pond environment: there were plants and algae, especially Najas flexilis, growing up through the mesh, so that the bottom edges of the enclosures were almost sewn into the pond bottom. The enclosures were also crawling with tiny tree frogs, as well as a legion of baby water scorpions, so I had a lot of fun just picking creatures off the enclosures as I pulled them out of the water.

The frogs are funny creatures: being tree frogs, they’re mostly terrestrial (okay, arboreal), and so not actually all that keen on being in the pond once they’ve metamorphosed from their tadpole form. They don’t swim very well at all—as soon as they stop actively propelling themselves, they float upright (it seems as if their heads are more positively buoyant than the rest of their bodies). And when they’re in open water they make a beeline for the nearest shoreline-like objects. This resulted in many frogs trying to climb up my legs.

Here’s a gratuitous frog picture. This little dude was sitting on top of a pole that was propping up one side of the enclosures. I thought this spot looked too hot and dry for a frog, but it seemed perfectly happy there—this funny hunkered-down pose, with legs tucked underneath the body like a sleeping cat’s, is their favoured posture.

So I guess my “Pond county almanac” is coming to an end. I have a couple of follow-up posts lined up, but I’ll no longer be at the ponds on a regular basis. This is a weird feeling, especially since it feels like summer’s only just started—as I’ve mentioned before, we’ve had unseasonably cold and wet weather this year. I think this has translated into fewer insects emerging from the ponds, although there are other variables that could explain the pattern I’ve seen. Here’s a picture of a section of enclosure from roughly this time last year: it’s covered with insect exuviae. When I took them down, there were about half as many exuviae as there were last year.

And finally, what the hell, here’s another frog picture. They’re so darn cute.

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Posts have been a bit sparse this month and short when they do appear because I’m preparing to defend my Master’s thesis. I am, however, still working at the ponds every day, so here is a little update.

This summer, despite being one of the hottest on record in the rest of Canada, has been cool and wet here on the west coast. While I find this annoying in some ways, it’s useful from a science standpoint because it’s extending the stickleback breeding season—the shallow water where my enclosures are set up doesn’t get so hot that the fish die. Thus my experiment is continuing for a few more weeks.

The sides of my enclosures are speckled with insect exuviae—mostly damselflies, but increasing numbers of dragonflies, especially the big Aeshna multicolor, as well. The killdeer have hatched another batch of chicks and recently a mother duck showed up with ducklings. (They seem to have left; probably because the plastic sides of the ponds make it very difficult for the ducklings to get out of the water.) There are still tadpoles of all sizes, and the largest of them are now full-grown frogs.

The Scotch broom and many of the native wildflowers are done flowering. Now, some white sweet clover—another invasive legume—is dominating the landscape. I’m not going to be trying to remove it: it can grow back from cuttings, and I don’t really have the time.

Inside the enclosures, especially those with other vegetation, filamentous green algae has been growing rapidly. The stickleback are good at keeping the areas around their nests clear, but it was threatening to cover some enclosures, so I’ve spent a lot of time scooping it out. Fortunately, I seem to have an ally in some chironomid (non-biting midge) larvae. They are tiny little bloodworm-like things, except green rather than red (actually, I think they’re transparent, and the green is the algae in their guts), that encase themselves in a layer of slime and graze on the algae. They’ve managed to control the algal bloom in several enclosures.

My favourite moment this week has been the appearance of fledgling barn swallows. The picture above shows two of them perched on the ropes that hold up my enclosures. There were three at one point, all huddled together, while one of their parents wheeled around a chirped at them. One by one, they all eventually took flight.

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…of the first of this year’s tree frog cohort leaving the water, a poetry translation break.

senem in lacus

ranunculus saltabat—

sonitus aquae!

I’m being a bit self-referential here, because this is my (rather hasty) Latin translation of a classic haiku, suggested by Wickedday‘s delightful and wistful poem, inspired by my original frog post.

I was hoping to arrange matters such that the haiku would also scan as a hexameter, but that didn’t work. (Anyone who can improve on this, or who has corrections, please chime in!)

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Caddisfly mystery

I’ve been seeing groups of caddisfly larvae clinging to the jelly-like frog egg masses (mostly after the tadpoles have hatched). Possibly they’re eating them? The internet tells me nothing.

Anyways, the ponds are full of tadpoles now, from tiny newly hatched ones to large ones with back legs. And I still hear the occasional frog call, so there’s more on their way.

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