While snowshoeing high, high in the mountains, on top of snow measured in feet, we came across what we thought was a spider. Instantly puzzled, we wondered what the heck a spider was doing walking across the snow on a not-at-all-warm day. Had we taken the time to count its legs, we would have known that it wasn’t a spider at all. Luckily I took pictures.
And because I geek-out over this kind of stuff, I had to figure out what it was. Drum roll, please…it was a snow fly. A snow fly? Who has ever heard of such a thing? Clearly not me. And in all the time I’ve spent in the mountains in winter I’ve never come across one.
Apparently these wingless flies are present in montane environments across North America, Asia, and Europe. They spend most of their adult lives in the subnivean* environment (new word alert!) making good use of mammal burrows and cavities in the snow created by rocks, fallen logs, and vegetation. The little research done on these flies reveals that adults most likely don’t eat at all, and only drink water from melted snow. What do the larvae eat? They are coprophagous** (new word alert #2!).
Aside from their winter strolls on the snow, high in the mountains, snow flies are different from most insects in other ways. Opposite from most other insects, snow fly larvae grow in the summer and pupate in the fall. The adults mate in the winter, which, scientists believe is one of the reasons they leave the relative “warmth” of the subnivean zone and go for a stroll. They are looking for a mate.
* the area between the surface of the ground and bottom of the snow
**feeding on the feces of other animals
Greenland shark at the floe edge of the Admiralty Inlet, Nunavut (Hemming1952)
Last week I had the honor of reading one of my picture books to a group of second graders (hello Dry Creek Elementary 2nd grade!). Afterwards they asked what I like to write about, and I explained how much I geek out over cool nature and science facts (like the velvet worm). Then, the very next morning a friend sent me a link to an article about Greenland sharks. I geeked out.
The first thing that caught my attention is that they are ENORMOUS yet we know very, very little about them. How is that possible? What we do know is that these elusive sharks can be over 20 feet long (comparable to a great white) and the surface of the skin is covered in denticles – toothlike projections. Greenland sharks love cold, very deep water around Greenland and Iceland, which is probably why they are seen so rarely. Down in the depths they blend into the murky darkness, moving ever so slowly. Their average speed? Less than 2 miles per hour. In addition, they are practically blind. That brings up the question, how do they catch anything to eat? The answer is, first of all, that they are not picky. They will eat just about anything, alive or dead (Arctic seals, reindeer, polar bears, beluga whales, fish, crustaceans), that ends up in the sea. They are scavengers for sure, but they are also ambush predators.
Yet perhaps the most interesting thing about the Greenland shark is how long they live: over 200 years. That is not a typo. And I checked multiple sources. Teams of scientists have used radiocarbon dating to determine the age of captured sharks. One female was approximately 400 years old. That means she was alive at the same time as Galileo, when the Taj Mahal was completed, and while Newton pondered gravity. Truly hard to comprehend, but fun to geek out over.
Robins are a common site across North America. They are so common that we often don’t give them much thought. Yet in the past months I’ve come to appreciate the common birds that populate my yard and visit my feeder, and I find them every bit as fascinating as more extravagant birds.
Photo by Joe Cosentino
First of all, robins can be found year-round in the contiguous states. Though some do migrate (especially those living in the northern part of the continent), most simply move into the woods in the winter where there are trees and shrubs with berries, and they roost in the trees. That’s why we don’t see them as often in the winter. When warm weather arrives, we will see them in parks and yards pulling up worms after a rainstorm. To find the worms, robins stand motionless, staring at the ground with their head tilted sideways. The search for worms will happen most often in the morning because robins stick to a routine menu: worms in the morning, berries in the afternoon.
If you do see a robin in the wintertime, you are most likely in the company of many more than one. These roosts, as they’re called, can include up to a quarter million birds! Surely I look forward to the days when they’re pulling up worms again, but I’m happy to see one any time.