Friday, October 31, 2014

have a creepy crawly halloween

In observance of this spooky holiday, we’re going to talk about something truly terrifying. Something that can make your skin crawl… something that goes bump in the night (albeit a tiny bump)… something that will try to suck the blood right out of you.

If you haven’t guessed, I’m talking about ticks. Those blood-sucking, privacy- stealing, creepy crawling arachnids.

I may be a little tick-sensitive at the present time. I just arrived back in Louisiana a few weeks ago and have already had red bug bites and one tick. Red bugs are one thing; they itch like crazy but you really don’t have to treat the bites. But when you find a tick on you, you have to physically remove it. Here you are, minding your own business, only to find out this little invertebrate has been on your person for several days, burrowing into your skin, and feeding on your blood. It was on you when you were going about your day like a clueless dope. You feel violated.

This bite looks to be a case of Lyme disease
transmission. But also, just kill me know.
And now, NOW you have to remove it with tweezers. You can’t just say, “hey, Miss Tick, I know you’re just trying to make a living, but I’m going to need you to please move elsewhere. What’s that? You’re happy to leave? Okay, thank you! Take care!” No no. You have to carefully tweeze it off, being careful not to smoosh it. And if you’re like me, you will of course accidentally smoosh it and not get the whole thing out.  And then you’ll feel disgusting and like a disease-ridden reject. And so goes life.

Obviously ticks cause me, among other people, a little anxiety. But like all living creatures, they are pretty cool in some ways. For one, they are not insects. They are arachnids- more closely related to spiders and scorpions than they are “bugs.”

Because they are so tiny, we often assume they do not have complex behaviors: that they wander their environment aimlessly until they find a host and dig in. But that is not so. They have a pretty cool system for food searching that is a classic reference case in ethology (animal behavior).

You see, animal behaviors are based off of releasers. A releaser occurs, then a behavior results.  For instance, a lizard flashing its red dewlap would be the releaser for female arousal. An animal running away quickly would be a releaser for a grizzly bear to pursue it. A Lord of the Rings marathon would be a releaser for Claire sitting in front of the TV watching it.

The presence of carbon dioxide and heat is a releaser for tick “questing” behavior. They sit perched like tiny gargoyles on the edge of leaves, waiting for a passerby. Once they sense increased levels of CO2 or heat in their immediate environment, they grip onto the source with their legs. This would make sense, since mammals breathe out CO2 and put off a fair amount of body heat.

In fact, biologists that research ticks use this knowledge to their advantage. They will put white sheets down on the ground and spray CO2 canisters around the underbrush. The ticks fall off onto the white sheets like little drunk idiots.

How many millions of years did it take for this releaser/behavior to be selected for? A million? Maybe less. I would think there would be a strong advantage for ticks that exhibited this behavior.

At any rate, hold your breath when walking through the forest. Wear clothes that insulate your heat.

And if you find that impractical, then invest in some tweezers and Xanex.