Cornelius’ Corner: Life Under the Ice
Good morning friends!
Are you staying warm? My heat lamp and log have been doing a great job in my tank, but they can’t warm up the whole outdoors. It was even too cold for me to go to the Delco Camp & Activities Fair this year, which is always one of my favorite outreach events!
With all the ice and snow, it got me thinking- what do aquatic animals do when the water freezes over? I did some research, and it turns out there are three basic strategies. Animals can either move to a non-freezing location, hibernate, or use special physiological adaptations to stay active. Below are three animals that live in the park. Let’s see what they’re doing!
Moving
The rainbow trout that live in the creek are a good example of animals that change their behavior when things start to freeze. Instead of moving between the creek’s runs and pools as they look for food, the trout head to the deepest pools with slow moving water that won’t freeze solid. They might also look for spots where groundwater flows directly into the creek. Ground water typically stays a little warmer than surface waters, so these spots are less likely to freeze too. Once at their chosen spot, the trout form schools that help them conserve energy and reduce the need for food. Swimming in schools allows them to use the slipstream effect to lower the effort it takes to stay in one place. That’s a pretty cool trick!
The creek’s deepest pool near the Log Cabin, where trout are schooling and slip-streaming
Rainbow trout in the deep pool in summer, by Celeste Sheehan
Hibernating
The snapping turtles that live in the wetland take a different approach to winter’s freezing temperature- why adapt when you can just sleep?! Each fall, when water temperatures start to drop, the snapping turtles increase their hunting and build up fat stores just like a hibernating bear! Then they burrow into the mud and leaves at the bottom of the wetland, deep enough that any ice layer won’t reach them. Then they lower their metabolism and start brumating, which is the reptile version of hibernating during unfavorable conditions. They may move around a bit to find a better position or do some slow laps, but generally they don’t need to hunt. When the wetland is frozen solid like it has been the last few weeks, they don’t even need to worry about breathing. They can absorb oxygen through their cloacas (where they lay eggs and excrete waste) even when fresh air is kept from the water by a layer of ice.
Wetland pools where snapping turtles sleep under a layer of ice
Snapping turtle sunning on the Frog Pond outflow bridge
Adapting
In the Frog Pond Outdoor Classroom, caddisflies are superheroes when it comes to dealing with ice and cold. There are many different species of caddisfly. Some species are very cold tolerant- they keep on grazing for algae, sometimes even off the bottom of the ice layer! They don’t have to worry about ice crystals damaging their bodies because they produce their own anti-freeze. Other species of caddisfly just let themselves freeze solid, using their anti-freeze compounds to protect important tissues and organs. With these protections, they can stay stuck in the ice for up to 6 months!
Hopefully we don’t have 6 months of ice this winter! I don’t want to miss the gorgeous spring wildflowers and hanging out with my friends.
Different species of caddisfly larvae found in the creek during macroinvertebrate studies
The Frog Pond Outdoor Classroom looks quiet, but caddisflies are happily grazing underneath
Stay warm everybody!
Your friendly (not currently in the) neighborhood corn snake!
-Cornelius
