A fish has marine biologists puzzled with its gin-clear blood, which doesn’t have any scales and only lives 3,200 feet below in the icy waters off Antarctica. This gin-clear species is actually known as the ocellated ice fish.
The Tokyo Sea Life Park is the only place with ocellated icefish in captivity, Agence France-Presse reports. “Luckily, we have a male and a female, and they spawned in January,” Satoshi Tada, an education specialist at the center, told AFP.
The ocean’s depths are rich with odd sea life, from giant squid to translucent sea anemones. Researchers now believe life around deep-sea vents may have arisen following the last mass extinction on Earth 65 million years ago, after a giant meteor impact killed off dinosaurs and other animals.
Scientists hope the mated pair of icefish and their offspring in Tokyo will help researchers unlock the secrets of how the fish manages to survive without hemoglobin to carry oxygen to its cells.
It’s possible, some scientists speculate, that the icefish’s unusually large heart might help move oxygen through its body using blood plasma instead of hemoglobin.
Also, with no scales to get in the way, the icefish may absorb some oxygen directly through its skin: Cold, polar water is richer in oxygen than warmer waters.
But the mystery surrounding the icefish’s lack of hemoglobin may take years to solve. “More studies are needed on the question,” Tada said.
Many antarctic species of cold-water teleost fish lack any kind of hemoglobin (sometimes also lacking myoglobin) or even red blood cells.
The water is so highly oxygenated at low temperatures that it can diffuse straight from the gills into the blood, then from blood to tissue.
Many of the “clear-blooded” fish species also have extensive capillary systems to ensure easier diffusion to other tissues.