The Seagull’s Leg
Was It Designed?
The Seagull’s Leg
▪A seagull does not freeze even while standing on ice with bare feet. How does this creature conserve its body heat? Part of the secret is in what are called countercurrent heat exchangers.
Consider: A countercurrent heat exchanger consists of a tube carrying a warm fluid that runs in close proximity to a tube carrying a cool fluid. If the fluids run in the same direction, only half of the heat is transmitted, at best. But if the fluids run in opposite directions, nearly 100 percent of the heat is transmitted.
The heat exchangers in a seagull’s legs cool the blood on its way to the feet to near freezing and then rewarm the blood as it returns. Concerning birds in cold environments, ornithologist Gary Ritchison writes: “The principle of countercurrent heat exchange is so effective and ingenious that it has also been adapted in human engineering projects to avoid energy waste.”
What do you think? Did the countercurrent heat exchange system in the seagull’s legs get there by chance? Or was it designed? *
[Footnote]
^ par. 6 Countercurrent heat exchangers are also present in humans, a number of fish, and many other animals.
[Diagram/Pictures on page 25]
(For fully formatted text, see publication)
The heat exchangers in a seagull’s legs warm returning blood
[Diagram]
32°C
0-5°C
[Picture Credit Line on page 25]
Seagull: © Michael S. Nolan/age fotostock
You May Also Like
AWAKE!
The Sea Otter’s Fur—Was It Designed?
Some aquatic mammals rely on a thick layer of blubber to stay warm. The sea otter uses a different method.
AWAKE!
The Emperor Penguin’s Feather Coat—Was It Designed?
What have marine biologists discovered about this bird’s feathers?
