Adaptation 101
When most people heard that I was going to the Alaskan Arctic to study spiders, the common response was “spiders can live in that cold environment?” Well, yes. Yes they do. How? Well the arctic wolf spider, like other living things up here, possess special adaptations to help them survive. So just what is an adaptation you may ask? Well that’s an easy one – an adaptation is any trait that gives an organism a better chance of surviving in a particular environment. Some arctic adaptations are easy – a polar bear’s white fur, for example. The camouflage of the white polar bear allows it to be an almost invisible hunter in a nearly white landscape. Poor seals never see that giant bear coming until it’s too late…
Caribou grazing just off the Dalton Highway. Caribou have many adaptations to help them in the tundra, such as long legs and wide hooves for walking in snow. Why might walking in a herd be an adaptation as well?
Arctic Adaptations
I continue to be amazed at the diversity of life here in the tundra. Looking out the window at the lush, rolling green hills, you would have no idea that most of the year those same hills are covered in snow. So how do things live here when the ground is usually snow covered and temperatures are consistently below freezing? Some animals, like the arctic ground squirrel, hibernate during the cold winter months. Some animals, like moose, wolves and some birds have hollow hairs and double layers of fur to insulate them against the cold. Other animals, like the wolf spider and some other invertebrates, have special chemicals in their bodies that are similar to the antifreeze you put in your car. Scientists are still not 100% sure of all the adaptations that exist in these invertebrates – there are so many different things these amazing animals do! Some go through diapause, which is just a fancy word for “developmental delay” – meaning that some of these invertebrates may stay in their pupal stage until conditions are better for them to emerge and be active.
Red Fox. What is the adaptation that helps the fox survive life in the Arctic?
Life under the Blanket
Even though the winters here are extremely cold (-20 C is common), some organisms never experience that cold, since they are trapped under a blanket of snow. The snow acts as an insulator for the organisms living in the soil, so they only have to protect themselves from near freezing temperatures. A lot of the soil invertebrates (refer to last week’s post) remain active under this blanket, but researchers are still investigating how their activity levels change during the winter months. Hey, it’s cold out here in January…would YOU want to research soil animals then?
Parasitism – A great adaptation to the Arctic?
One other interesting adaptation that keeps rearing its ugly head around here is parasitism. Almost every day I’ve learned about a new type of parasite that exists here – like the nose bot fly that lays its (live) larvae in the noses of caribou. The larvae travel through the animal’s nose and end up in the throat, where they grow until the next spring. Seems like a pretty good way to keep warm in the winter, right? Ever wonder why caribou are always shaking their heads and running off in strange directions from the herd? Thank the bot fly.
Poor caribou. If it isn’t the mosquitoes in the summer that get them, it’s the bot flies. Or the warble flies. Image courtesy of Wikipedia.
Some of the most prolific parasites here in the Arctic are the wasps. There are lots of different types of parasitoid wasps around here, but the ones that are of interest to me are the ones that lay their eggs inside the egg sac of the wolf spider. This really isn’t an adaptation to the cold, but it is an adaptation nonetheless. We’ve captured over 30 living female wolf spiders in hopes that we may see some egg sacs that contain these parasitoid wasps. Let’s hope that our spider mommas stay alive in the lab long enough to hatch their spiderlings. Or wasps.
Female wolf spider with egg sac.
Thankfully we have a steady stream of mosquitoes in the lab to keep the spider mommas well fed.
Ask the Team
Have any questions about what you just read or anything concerning adaptations? Questions about life here at Toolik or previous posts? Make sure you are asking questions in the “Ask the Team” section of my expedition page so that I can get back to you!