| Welcome to Natural Hazards Forum. We hope you enjoy your visit. You're currently viewing our forum as a guest. This means you are limited to certain areas of the board and there are some features you can't use. If you join our community, you'll be able to access member-only sections, and use many member-only features such as customizing your profile, sending personal messages, and voting in polls. Registration is simple, fast, and completely free. Join our community! If you're already a member please log in to your account to access all of our features: |
| Warm blood makes unusual opah fish succeed in oceans | |
|---|---|
| Tweet Topic Started: 15 May 2015, 12:50 AM (10 Views) | |
| skibboy | 15 May 2015, 12:50 AM Post #1 |
|
14 May 2015 Warm blood makes unusual opah fish succeed in oceans © NOAA/AFP/File | This photo courtesy of the National Oceanic and Atmospheric Administration Fisheries/Southwest Fisheries Science Center shows an opah fish being released with sensors to track temperatures as it dives MIAMI (AFP) - The silvery, round-bodied opah fish is the first warm-blooded fish known to science and this unusual ability gives it a competitive edge in the cold ocean depths, researchers said Thursday. Also known as a moonfish, the creature is about the size of a tire and can warm itself much the same way as a car radiator, researchers said in the journal Science. The fish has blood vessels in its gills that carry warm blood from the body's core. These vessels wrap around other vessels near the gills, where the fish breathes, bringing in oxygenated, cold blood. The result is a self-made heating system that keeps the fish's brain sharp and its muscles active so it can swim fast and grab prey. By attaching temperature monitors to opah fish off the US west coast, researchers found that the fish had an average muscle temperature "about five degrees Celsius (nine degrees Fahrenheit) above the surrounding water while swimming about 150 to 1,000 feet (45-300 meters) below the surface," the study said. Most fish are cold-blooded, so the discovery of a fish that can warm its body much the same way as mammals and birds was a surprise to scientists. "Before this discovery I was under the impression this was a slow-moving fish, like most other fish in cold environments," said lead author Nicholas Wegner of the National Oceanic and Atmospheric Administration's (NOAA) Southwest Fisheries Science Center in La Jolla, California. "But because it can warm its body, it turns out to be a very active predator that chases down agile prey like squid and can migrate long distances." Opah fish live in the deep ocean where predators tend to ambush prey rather than chase it. Some other fish, like tuna and some sharks, can warm up some certain parts of their bodies and muscles to boost swimming performance in the cold depths, but their internal organs quickly get cold, forcing them to rise to shallow waters in order to warm up. With red fins that are constantly flapping, the opah fish stays warm even when the water gets colder, speeding its metabolism and maintaining a quick reaction reflex. In addition to the network of warming blood vessels, the opah fish have fatty tissue around the gills, heart and muscle tissue to insulate itself and stay warm. "There has never been anything like this seen in a fish's gills before," Wegner said. "This is a cool innovation by these animals that gives them a competitive edge." Source:
|
![]() |
|
| skibboy | 16 May 2015, 12:15 AM Post #2 |
|
Warm-blooded fish traps its own heat in the deep By Jonathan Webb Science reporter, BBC News 15 May 2015 ![]() The fish maintains its brain and heart about 3C warmer than the surrounding water The large and colourful opah has become the first known "warm-blooded" fish, as scientists discovered it can regulate the temperature of its whole body. The opah traps warmth from its flapping fins, which are well insulated by fat. It uses that heat to keep its heart, brain and other organs warm while it swims to depths of hundreds of metres. Other fish like tuna can warm specific body parts, boosting performance at key times, but whole-body "endothermy" has not been observed in a fish before. The research is published in the journal Science. Mammals and birds are traditionally thought to be the planet's only warm-blooded animals, keeping their body temperature consistently warmer than the outside environment. Fish and reptiles are almost entirely cold-blooded, or "ectothermic"; they are at the mercy of the environment for their warmth and largely get by on slower metabolic rates. ![]() The fish in the study weighed up to 68kg Some fish are known to use so-called "regional endothermy", including tuna, which can warm their swimming muscles for a burst of speed when pursuing prey. But deep-water fish such as the opah are usually relatively slow and sluggish, tending to ambush their prey instead of making chase. This makes the new findings quite a surprise, according to the study's first author Nicholas Wegner. Big fish "Before this discovery I was under the impression this was a slow-moving fish, like most other fish in cold environments," said Dr Wegner, from the Southwest Fisheries Science Center run by the National Oceanic and Atmospheric Administration (NOAA) in the US. "But because it can warm its body, it turns out to be a very active predator that chases down agile prey like squid and can migrate long distances." Dr Wegner and his colleagues measured the temperature of different body parts in freshly caught fish. They also implanted thermometers while the animals dived beneath the waves. They discovered that the opah's muscles were consistently about 5C warmer than the surrounding water, even when they descended between 50m and 300m under the surface, where the water is typically between 8C and 11C. ![]() Dr Wegner and his colleagues studied the opah off the Californian coast The opah's head region and heart are also kept about 3C warmer than the water. This might not seem like a huge advantage, but it requires some sophisticated thermal engineering - especially for a beast this size: the opah in the study weighed from 22kg to 68kg but the species has been known to reach 270kg. Counter-current exchange Instead of undulating its body like most fish, the opah propels itself by flapping its pectoral fins. These very active muscles are insulated from the water by a thick layer of fatty tissue, trapping the warmth. Crucially, when blood is pumped into the animal's gills to collect oxygen, heat loss is minimised by a dense, intertwined network of blood vessels called a rete mirabile. At the surface of the gills, blood picks up oxygen and loses warmth. But as it passes back through the sponge-like rete mirabile (Latin for "wonderful net"), it regains some heat from the still-warm blood arriving from inside the fish's body. The design was a bit like a car's radiator, Dr Wegner said. "There has never been anything like this seen in a fish's gills before. This is a cool innovation by these animals that gives them a competitive edge. "The concept of counter-current heat exchange was invented in fish long before we thought of it." ![]() Silvery and red in colour, the opah - Lampris guttatus - is found in oceans all over the world Source:
|
![]() |
|
| 1 user reading this topic (1 Guest and 0 Anonymous) | |
| « Previous Topic · Science & Nature · Next Topic » |










3:50 PM Jul 11