Nurse sharks have the lowest metabolic rate measured in any shark, according to new research from Mote Marine Laboratory. This “sluggish lifestyle” likely contributed to the survival of the species over the last several million years.
When we picture sharks, most of us probably imagine the big, charismatic ones like great whites or makos. These guys are active predators that chase their prey. Nurse sharks, on the other hand, are pretty lazy predators. They wait under rocks and in crevices where they can snap up unsuspecting prey as it wanders by without expending much energy.
Nurse sharks are able to sit on the ocean floor and wait for meals because they are one of few species of sharks that can pump water across their gills — they don’t have to constantly swim in order to breathe.
To study their metabolism, the researchers measured the oxygen consumption of nurse sharks in sealed tanks. They found that the sharks’ average metabolic rate when swimming was only 18% of a mako shark’s metabolic rate.
“If we know about a shark’s metabolism — their basic energy needs — then we can start to estimate their energy use in the wild to better understand their impact on the ecosystem,” Dr. Nick Whitney, manager of the Behavioral Ecology and Physiology Program at Mote, explained in a news release. “Sharks are often the top predators in the food web, consuming a lot of calories from animals on lower levels. As such, they often have a larger impact on the balance of the ecosystem than other species. To better understand the ecosystems that we want to preserve, we need to better understand sharks.”
Whitney and the other study authors note that nurse sharks are some of the most abundant species in tropical and subtropical ecosystems, so it’s clear that this low-energy strategy works.
“With their low metabolic rate, nurse sharks are pretty lazy — but the interesting thing is that this can be a very successful strategy,” Whitney said. “Nurse shark populations are doing very well compared with many other shark species. Their low-energy strategy is not the only factor, but it is part of their success.”
To learn more:
- Read the Mote news release: Shark With Lowest Known Metabolism is a Sluggish Success
- Read the full study: The effects of temperature and swimming speed on the metabolic rate of the nurse shark (Ginglymostoma cirratum, Bonaterre)
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