Sunday, July 10, 2016

A xenomorph moment with an anole (EDIT: Video link provided below)

Late last night, I returned to home base after capturing anoles at several sites for additional mate-preference trials. I started to organize the lizards that I captured and process them before placing them into their cages.

In addition, I had one male Anolis krugi that I held captive for a two days from a previous collection night. I try to catch extra male A. krugi when I can because they’re by far the rarer demographic that I need for my trials and can be used as insurance in case I can’t find enough for the following capture-session. This anole, from the northern hills of Yauco, was a beautiful 53mm-SVL whopper and he wasn’t at all shy to eat the crickets I fed him during his time in captivity.

As I was about to remove him from his cup container to assign him his trial cage I noticed something protruding out of the side of his torso. And that something was moving. “Is that a bot fly?!?” I exclaimed in my thoughts. The larva was just idling with its head (assuming it’s the head end) sticking out of the anole. As many biologists might do if they have the equipment, I ran to my car and grabbed the camcorder and some tweezers.

With the camcorder on and recording, I took the anole out of his container. But as the lizard briefly squirmed in my grasp, it stimulated the larva to flee the scene. I would’ve uploaded the video here of the scene but my current internet provider cannot handle the byte-load. So here is a screen shot. 

After squirming a bit, the lizard calmed down while the larva inched its way out of the hole.
It was pretty like a slightly boring, calm rendition of the scene from the 1979 film, Alien - but the lizard survived the ordeal albeit with a large dry wound exposing his raw musculature.
I decided not to use him for trials and put him back in his cup container. I procured the wiggly larva from the floor, sampled it into a vial and alcohol, and continued on to process the rest of the lizards for the night.

Once all the lizards were measured and in their cages, I briefly googled what this parasitic larva could be. Turns out it is not likely to be a botfly species such as the human botfly (Dermatobia hominis) of family Oestridae, but of a different yet closely related family, Sarcophagidae, the flesh flies.

I found that a fellow anole researcher, Dr. Travis Ingram, reported a similar case with an Anolis pulchellus at El Verde field station with an outcome more fitting of a Ridley Scott movie. The pictures he provided of the larvae seemed just as girthy as the one that emerged out of my A. krugi. Looking at the comments of his post, it appears there have been at least several of these observations in A. carolinensis and A. pulchellus.

Dr. Ingrams’s own googling led him to a paper by Irschick et. al. (2006) which provides insight on the parasitism of a Anolis carolinensis by a sarcophagid fly. Dr. Ingram went the extra kilometer and provided his parasitic larvae with substrate to complete their life cycle and managed to observe the adult fly stage, possessing the characteristics similar to sarcophagid flies.

And just as Dr. Ingrams’s also noted, I noticed nodules bulging from under the same A. krugi’s skin. Perhaps they are other larvae? Has anyone ever seen this in an A. krugi?

The following morning, I checked on the A. krugi male and saw he was still kicking and seemed that he’ll get to live another day at his home site. This was definitely a cool thing to observe, though I much prefer ‘not’ to observe it happen to the rest of my anoles for the rest of the season.
The next morning the wound was dry but still open.
This guy had at least two nodules at the edge of his ventral side.

-Eddie Ramirez

EDIT - 3/October/2016 : Click here to watch the larvae exiting from its host!

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