Fall is here! Are you Warm Blooded or Cold Blooded?
Photo by: Nicholas A. Tonelli
Being cold blooded, or as scientists say, being an ectotherm, like frogs and turtles, means you have poor to no means of making your own body heat. Heat is very important to living things because our bodies perform best at an ideal temperature, which can be different for different types of animals. Metabolic processes in our cells drive our bodies to breakdown food and turn it into the energy we use to breathe, think and move.
If you are a warm blooded animal, or as scientists say, an endotherm, like a beaver or human, you have a body full of heat making mechanisms inside your cells that run 24/7 to convert food into energy. Because these processes are always running, and at high metabolic rates, endotherms need to eat more food, more frequently, to maintain their body functions. Before winter many endotherms will excessively eat to build up food fuel in the form of body fat. The body fat will be used in winter when food is scarce. Endotherms also have to keep their engines at a specific temperature and help to do this using by insulating their bodies with fur, feathers, blubber or for humans a winter coat.
Cooler nights and reductions in available daylight might bring out the best of our fall colours, but what does it mean for Ontario’s amphibians and reptiles? With water temperatures slowly decreasing, and basking sunlight becoming patchy at best, these seasonal changes signal their metabolism to slow down and get ready for winter hibernation.
Ectotherms, like frogs and turtles, don’t have the internal mechanisms that endotherms have to make body heat, so they rely on outside heat sources (like the sun) to maintain their metabolism at a steady temperature. They still need to eat, but they can eat less than an endotherm since their food is not being used to create their body heat. In autumn, the environment of Ontario’s reptiles and amphibians will slowly cool down below 15oC. At this temperature their metabolism is so slow that they can no longer digest food properly, so these creatures stop eating, stop growing and move only in slow motion. Even if they fueled up by eating more food, they cannot convert that food into energy without the warmth from the environment around them.
When it’s cold, everything in an ectotherm’s body is moving at a slower pace, so it is much easier for predators, like otters or birds, to catch endotherms to build up their own winter food stores. Unlike some types of animals, amphibians and reptiles have a hard time migrating to a warmer location. Travelling down south to sunny Florida for a winter vacation is just out of the question for a slow creature like the turtle! To help prevent predation in the fall, most amphibians and reptiles will stay under the water and camouflage in the mud and dying vegetation. Next time you go for a hike near a wetland in autumn, think how cool it is that even though you can’t see or hear anything in the water, it’s still full of living creatures sleeping just below the surface.
In the winter, when the water reaches around 4oC, the amphibians and reptiles metabolism is running at the slowest pace of the year. A turtles heart beat in the winter can be only once every 10 minutes, they can go months without eating, and they won’t come up for a breath of air during their hibernation from November – April! Species like the Wood Frog can enter a state of such deep hibernation that their body can freeze and their internal functions become suspended in time! Not to worry though, Wood Frogs defrost every spring and signal the arrival of the warm weather as one of our first emerging amphibians.
Keeping wetlands clean and healthy in the fall is important for the many creatures still living in them. You can help ensure they have a clean place to sleep away the colder months by cleaning up litter around wetlands before the winter snow covers it up!