Winter in Chicago is in full swing. We bundle up in long coats, soft hats and warm gloves to take on the Windy City chill. Although we feel cold when we step outside in January, our internal temperature stays around 97.9 degrees Fahrenheit, but how?
As warm-blooded mammals, we’re equipped to stay warm despite the changing environment. Species in the aquatic animal world have their own ways of maintaining internal temperature, let’s dive in!
What is cold blooded and warm blooded?
Warm blooded and cold blooded are terms used to classify how an animal maintains its internal temperature. We can sort most animals within these two groups.
Warm-blooded animals, or endotherms, heat themselves from within. They have various adaptations that help them insulate to keep the heat they create, like thick layers of blubber, fluffy feathers or dense fur. They can also regulate and maintain a core body temperature with their metabolism! When warm-blooded animals eat, they digest and extract energy from food. After, they burn through energy and produce heat. Typically, warm-blooded animals can keep their internal temperature within a specific range regardless of their environment. This allows each species to live in a larger range of environments since they do not rely on external factors. You can find warm-blooded animals from the icy coasts of Antarctica all the way to the sunny beaches of the Caribbean!
Think of warm-blooded animals as fire pits. Just as a fire requires a constant source of wood to keep burning, mammals require food consistently to regulate temperature. No matter the outside temperature, 10 degrees or 80 degrees, the fire will keep burning as long as we supply an energy source.
Cold-blooded animals, or ectotherms, can’t create heat from within. They depend on external heat sources — like the sun — to maintain a steady body temperature. Their internal temperature is variable and adopts the surrounding temperature as their own. To warm up, a lizard might sunbathe on a toasty rock. To cool down, they may burrow underground or find shelter in the shade.
Cold-blooded animals are like solar panels because their internal temperature depends on the environment. When it is sunny, solar panels soak up that energy. When it’s cloudy, it’s harder to source energy, and for cold-blooded animals, regulate body temperature.
Who’s who?
All mammals (like us humans!) and birds are warm-blooded. Most fishes, sharks, frogs, reptiles and invertebrates are cold-blooded. At Shedd, encounter cold-blooded animals like the caiman lizard, fringed leaf frog or electric eel in Amazon Rising. Then take a stroll to the Oceanarium and meet beluga whales, warm-blooded mammals perfectly adapted with thick layers of blubber to live in frigid ocean water.
Being warm-blooded or cold-blooded has its benefits and disadvantages in the animal kingdom. Cold-blooded animals can survive with a limited amount of food, but warm-blooded animals can thrive in a wide range of environments with a steady food source.
Sea otters thrive in cold costal water without layers of blubber because of their fast metabolism and thick layers of fur, with roughly 1 million hairs per square inch! Otters will eat up to one quarter of their body weight per day to stay warm in cool water. For a typical adult sea otter, that’s up to 15 pounds per day being converted into heat like a furnace!
While warm-blooded and cold-blooded animals have differences, they share a common trait: they all deserve protection and conservation. Protecting aquatic life, no matter how they keep warm in the winter, is at the heart of Shedd’s mission. You can help spark compassion, curiosity and conservation for the aquatic animal world when you visit, donate or become a member.