Monthly Archives: October 2011
… I want to be an entomologist!
I gave a seminar talk for my department last night, and that was my title. It was supposed to be a brief overview (like 20mins) of my interest in science, what I’ve done at grad school so far, and what my research goals are. I rambled on for like 40 minutes, haha, I was told it was entertaining but I hope no one got too antsy! I could have easily talked for an hour or two. I really enjoy public speaking and want to get as much practice as I can.
This is the photo I opened up with. It’s one of my favorites. My indoctrination started early!
I think I still have that butterfly net in my parents’ garage somewhere.
In other news, my life continues to get crazier with research and schoolwork and teaching and trying to see my boyfriend for a few minutes once in a while. My caterpillar work is relegated to working with preserved specimens – all of mine have pupated or preserved, woohoo! Lots of organization to do (typing/printing labels, transcribing my notes into something coherent, editing and organizing photos) and now I’ve got term papers to start thinking about as well. Luckily the two I have to write will be about some aspect of my own research (one is for systematics, and the other is for evo devo). I’ll do my best to throw some interesting content in this direction when I get the chance!
Caterpillars have some really ridiculous adaptations. There are so many times I look at a caterpillar and think “that’s just silly”, or “is this thing out of its mind?”. And there are always new surprises.
Caterpillar eyespots are one of those ridiculous things. Big cartoonish eyes, staring up at you, daring you to be startled or fooled into thinking it’s really a monster. These eyespots are often accompanied by an enlargement of the body – either solid or inflatable. The can be a variety of shapes, sizes, and colors. Some are simple round dots, while some are oblong and appear to follow you like the eyes in a creepy painting. Some even have little white reflection spots! They can be on either end of the body, hidden or always on display, looking like a snake or who-knows-what. This strategy predominantly occurs in the tropics, among species which hide in rolled leaves.
The question, of course, is… why? Why did so many species of caterpillars, in a variety of lineages, all evolve different techniques for the same eyespot phenomenon? The answer is most likely: small insectivorous birds.
When you are a bird in the tropics, you have some basic needs. Find food, and stay alive. Caterpillars are delicious, while snakes are dangerous predators. If a bird sees a pair of eyes staring back at them, they have only a split second to decide if it’s worth the risk distinguishing between dinner and becoming dinner. Most often, the choice will be “no thanks, I would rather not disturb that potential predator”, even though the eyes were in fact on the rear end of a caterpillar. It has been suggested that this is an innate response to any startling appearance of eyespots, and not learned by trial and error. So instead of being a normal mimicry complex, the caterpillars are simply finding their own ways to take advantage of this weakness. It does not have to be a perfect match, but enough to make the bird think twice. This occurs mostly in the tropics due to the higher number of small venomous snakes lurking in the vegetation, though we have a few notable species in North America. The spicebush swallowtail has some wonderful eyespots. Perhaps it is relying on the innate responses of migratory birds which spend time in the tropics?
Spicebush swallowtail caterpillar. Image from bugguide.net
So far most discussions on this topic have had wonderful hypotheses, but are devoid of much data. Some scientists are working toward changing that, and I am excited to see what insights are gained.
Janzen et al. 2010. A tropical horde of counterfeit predators.
Eisner 2003. For Love of Insects.
I’m not the only grad student studying caterpillars.
This guy is looking at caterpillar eyespots. His research sounds like a lot of fun!
Remember that allergic reaction I had to Acronicta impleta?
I still have a red bumpy rash. I mostly don’t notice it, but once in a while it gets really itchy. Benadryl cream helps temporarily, but has not cured it.
I can’t wait to test out some of my other species next summer.
An adorable animation from Minuscule:
While this is cute, I of course have a few issues with it.
1) Anatomy. I do appreciate the attempt to separate the six true legs and the prolegs, but there are too many prolegs for an inch worm caterpillar. Though they were separated to get the inching motion, which is good. I can forgive the eyes for dramatic effect, though there are supposed to be more (up to 6 on each side).
2) They are sexually immature. Caterpillars do not find love – adult butterflies and moths do. Caterpillars are simply the eating-machine stage, utterly uninterested in a mate until after pupation. They have developing gonads, but they are non-functional.
3) Wrong “worm” in the apple. Inch worms are in the family Geometridae (and a few in Noctuidae), and they do NOT eat apples. It’s the codling moth caterpillar (Cydia pomonella), in the family Tortricidae, that is the typical “worm” that burrows into apples.
As I bet you can guess, I’m really terrible to watch movies with.