Children in the sea off Hawaii.
Many fish and marine mammals are expected to fall into deeper waters from warm surfaces, but the surrounding temperature is only a few degrees higher than the ice point, and therefore they have to face the challenge of low temperatures. They need to ensure that new generations are sufficiently active for hunting.
At cold ocean depths, a “mild hunter” is a good way of stopping the use of oxygen and thus preserving heat. Two sides have evolved into a unique ability to avoid falling physical temperature when they fall into cold deep-water hunting.
“For any fish, the fastest loss of heat is arsenic.” Mark Royer, a doctoral researcher of the Institute of Marine Biology at the University of Hawaii, United States of America, said that, because of a large number of warm blood flowers, it was “in essence like the great bulk heaters tied to the head”.
A number of fish, such as whales, are in great shape that enables them to keep temperatures while dividing. Other fish, such as tuna, marin fish and white and grey sharks, have been added to the special heat exchange system to avoid excessive body loss.
Both sides have neither these physical advantages nor the adaptive capacity, but one finds that their depth of 800 metres below the sea is fast and repeated.
In order to understand how sharks respond to temperature changes, Royer and colleagues have developed a device consisting of instruments of measuring depth, temperature, location and movement, as well as a search needles embedded in the muscle near the back, to record the core temperature of sharks. The device will break after a few weeks and float to the surface to send a signal.
Three double-hulles captured on the coast of Hawaii are embedded in this device.
In a paper published on 11 May of the Science, the Panel reported that two coconuts were dividing several times in deep water at temperatures ranging from 5 to 11 degrees Celsius, of which one shark was dividing six times in deep water at approximately 20 degrees Celsius per night, each for five to seven minutes and then floated water surface. For most of the time spent on shark submarines, temperatures remain unchanged.
According to Royer, sharks are effectively “gas” in order to maintain stability at the core temperature, without strangling or lipping in the dividing process. “If there is no water on the cassava, no body heat will be emitted.” Royer stated that “when they are close to the surface, they can slow down speed, strang up and restart breathing, because they are not as cold as the seabed.”
Mark Meekan, a fish economist at the Institute of Oceanography, University of Western Australia, said that oxygen intake was stopped in this way, indicating that double cookers could cope with a sharp drop in blood oxygen levels in the event of潜水, although their mechanisms had not yet been found.
“These may be to slow the movement of hearts and muscles, thereby slowing the entire flow of blood.” Meekan stated that the organization and blood of sharks may have moved into a unit that can accommodate more oxygen, similar to the adaptive capacity of people living in high altitudes.
At present, although the first fish is found to be capable of “gas”, the marine biologists of James Cook University, Simpfendorfer, say that other sharks or fish may have the same adaptive capacity. (Li wood)
Information on relevant papers: