Scientists Discover The World's First Warm-Blooded Fish
The large, round fish—about the size of a manhole cover—uses its warm
blood as an advantage in the ocean's freezing depths.
Deep-water fish called opah appear to be the first fully warm-blooded
fish species ever discovered, according to a new paper published in
Science. Researchers say the unique biology behind opah, also known as
moonfish, allow the species to operate at peak performance even within
frigid ocean depths.
Being warm-blooded has its perks. Birds and mammals (or endotherms)
conserve their internal heat to maintain high body temperatures, which
helps them flee predators, chase prey and thrive in sub-zero climates.
But fish—and other cold-blooded animals, like reptiles and
amphibians—aren't so lucky. Most deep-sea fish move slowly, preferring
to ambush prey rather than give chase, as their low body temperatures
(and reaction speeds) mirror the cool ocean water. But now, scientists
say they have discovered one exception to this rule: opah. "It's a
real advantage if you're in this deep, cold habitat and you're
swimming around with a warm body," says Nick Wegner, an NOAA fisheries
biologist and lead author on the paper. "It increases the rates of all
the reactions that occur within the body—you can swim faster, see
better, react faster and capture cold-bodied prey that are not able to
respond nearly as quickly."
Opah, which resemble large, colorful tires, thrive in the deep sea and
are an increasingly popular seafood. Although Wegner had been studying
opah for years, he recently noticed that warm blood vessels leaving
the fish's heart wrap around cooler blood vessels returning from its
gills. Later, he determined that opah generate heat by flapping their
pectoral fins, and retain that heat through this dense layer of blood
vessels. Opah's internal heating system is capable of keeping the
fish's heart and brain at peak performance, even at depths of up to
1,300 feet. Certain tuna and shark species also retain body heat, and
warm select muscles for high-performance hunting, but these species
are far from warm-blooded: Most of a shark or tuna's body (including
its heart and other vital organs) remains cold. "Opah is the first
fish that can circulate warm blood throughout the entire body, and
that gives it some advantages over tuna and shark species," Wegner
says. "Since they can keep their entire bodies warm, they can stay
down deep, continuously close to their forage base."
blood as an advantage in the ocean's freezing depths.
Deep-water fish called opah appear to be the first fully warm-blooded
fish species ever discovered, according to a new paper published in
Science. Researchers say the unique biology behind opah, also known as
moonfish, allow the species to operate at peak performance even within
frigid ocean depths.
Being warm-blooded has its perks. Birds and mammals (or endotherms)
conserve their internal heat to maintain high body temperatures, which
helps them flee predators, chase prey and thrive in sub-zero climates.
But fish—and other cold-blooded animals, like reptiles and
amphibians—aren't so lucky. Most deep-sea fish move slowly, preferring
to ambush prey rather than give chase, as their low body temperatures
(and reaction speeds) mirror the cool ocean water. But now, scientists
say they have discovered one exception to this rule: opah. "It's a
real advantage if you're in this deep, cold habitat and you're
swimming around with a warm body," says Nick Wegner, an NOAA fisheries
biologist and lead author on the paper. "It increases the rates of all
the reactions that occur within the body—you can swim faster, see
better, react faster and capture cold-bodied prey that are not able to
respond nearly as quickly."
Opah, which resemble large, colorful tires, thrive in the deep sea and
are an increasingly popular seafood. Although Wegner had been studying
opah for years, he recently noticed that warm blood vessels leaving
the fish's heart wrap around cooler blood vessels returning from its
gills. Later, he determined that opah generate heat by flapping their
pectoral fins, and retain that heat through this dense layer of blood
vessels. Opah's internal heating system is capable of keeping the
fish's heart and brain at peak performance, even at depths of up to
1,300 feet. Certain tuna and shark species also retain body heat, and
warm select muscles for high-performance hunting, but these species
are far from warm-blooded: Most of a shark or tuna's body (including
its heart and other vital organs) remains cold. "Opah is the first
fish that can circulate warm blood throughout the entire body, and
that gives it some advantages over tuna and shark species," Wegner
says. "Since they can keep their entire bodies warm, they can stay
down deep, continuously close to their forage base."
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