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. (newhealthguide.org) |
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.
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