Turns out the nurse shark has the slowest metabolism of any shark ever recorded! These lazy sharks spend most of their time laying in one spot on the ocean floor, until nighttime when they emerge to hunt. Unlike some species of shark that have to swim to keep water flowing over their gills, nurse sharks don’t need to move to breathe, and can sit motionless for hours. But to be this lazy, the sharks need special adaptations like a super slow metabolism. Scientists collected and studied nurse sharks and several other species in a lab in different water temperatures and at different times of the day. Some results were predictable, like the fact that the nurse shark’s metabolism was slower than sharks that breathe through “ram ventilation” (swimming with their mouths open to allow water to pass over their gills), but they were surprised to learn that nurse sharks metabolized at a much slower rate than any other species of shark, including others that are considered sedentary. Having such a slow metabolism means that when nurse sharks do finally emerge for food they expend a lot of energy but, instead of being a disadvantage, it allows them to be bums most of the day! I am a little jealous of these lazy sharks!

Want to learn more? Visit https://www.sciencenews.org/blog/wild-things/slow-moving-nurse-sharks-have-metabolism-match

Feb. 17, 2016