The most well-known krill is Antarctic krill, followed by Pacific krill and beauty krill.
The reason why Antarctic krill is most well-known is that it has the largest number. In the 20th century, when Antarctic scientific research and exploration technology was not so advanced, Antarctic krill saved the lives of many researchers.
In the ice-covered Antarctic, once researchers lose their supplies, Antarctic krill is their only source of food.
"Xiang Hui, close the door." Xiang Yang shouted.
Xiang Hui quickly did as he was told and pulled down the iron rolling door of his house.
"Turn off the lights too." Xiang Yang continued.
"Ah? Second brother, what are you going to do?" Xiang Hui asked puzzledly.
"You'll know once you turn it off." Xiang Yang said mysteriously.
Xiang Hui turned off the lights in the hall with a head full of question marks, then turned back to look at Xiang Yang, "Second brother, the lights are turned off, what should we do next...ah!"
Xiang Hui's eyes were fixed on the fish tank containing the krill, or to be more precise, on the three krill in the fish tank.
"Second brother, this plain and light-colored krill can glow." Xiang Hui said in shock.
Xiang Yang smiled and said, "That's right, it is indeed krill. Now we can turn on the lights and the door."
Xiang Hui quickly turned on all the lights in the room, then rolled open the door and smashed it.
After finishing all this, Xiang Hui asked again: "Second brother, can this plain and light-colored krill glow?"
Xiang Yang nodded. "To be precise, among the more than 80 species of krill that have been discovered so far, except for a few deep-sea krill, all the remaining krill can glow."
Krill have special spherical light organs in their bodies, which are located on the ventral side of the eyestalk, the base of the appendages on the chest and the abdomen.
These light organs throughout the krill's body allow the krill to emit beautiful phosphorescence in a dark environment, which is where the krill's name comes from.
After numerous experiments, marine biologists discovered that the phosphorescence emitted by the light organs in krill is caused by an enzymatic chemiluminescence reaction, which is very similar to fireflies, except that the luciferin in krill is activated by luciferase. Since krill itself cannot produce luciferin, it must absorb this substance from food containing dinoflagellates.
It is also worth mentioning that the luminescence of krill also violates the theory of biological evolution.
Because krill do not rely on phosphorescence to hunt or attract prey. Even if they attract prey, they will usually be killed by the prey because they are too fragile. After all, the average length of the entire family is only one or two centimeters.
Scientists have different opinions on why krill do not obey the theory of evolution and emit phosphorescence, and no one can convince anyone else.
Some people say that krill glow in order to attract females for mating, and the effect is somewhat similar to that of a peacock spreading its tail. However, this statement is the most ridiculous, because krill will still emit bright phosphorescence even when they are not courting or when their courtship has been successful. So it is obvious that there is an essential difference between the phosphorescence emitted by krill and the spread of a peacock's tail.
Some people say that krill luminescence is a social activity of krill. This statement is more reliable, because this social activity consumes krill after all.
Xiang Yang carefully looked at the krill in the fish tank. To be honest, it was the first time that Xiang Yang saw the beautiful krill in plain and light colors.
The plain-clothed light-colored krill have a very vertical migration route, and most of them choose to live like this:
During the day, the plain, light-colored krill dive to the deeper seabed and bury themselves in the sea sand to sleep.
At night, the beautiful, pale-colored krill approach the shallow waters near the surface.
Since Xiang Yang seldom moves on the seabed at night, and the plain and light-colored krill are really small, after burying themselves under the beach, there is no trace of them on the surface, so Xiang Yang has never seen this kind of krill so far.
Of course, not all krill choose to hide during the day and come out at night.
There are also some very rampant and domineering ones in the krill family.
For example, Antarctic krill.
Antarctic krill feed and reproduce on the water surface during the day.
The result of doing this... ... at least it has made a significant contribution to human scientific research. If it weren't for the existence of Antarctic krill, I don't know how many scientific researchers would have starved to death during the difficult period of supply in Antarctica.
Of course, the Antarctic krill that are attacked will not sit idly by.
Antarctic krill have no way to deal with fully armed human researchers, but when facing other marine predators, Antarctic krill do have a certain ability to survive.
Under normal circumstances, Antarctic krill use their swimming feet as propulsion and swim forward several centimeters per second. When encountering danger, Antarctic krill will move backwards quickly under the propulsion of their tail segment and tail limbs.
The backward swimming speed of Antarctic krill can reach an astonishing 0.8 meters per second, which is dozens or hundreds of times the normal speed. Ordinary predators simply cannot catch the krill that are escaping backwards.
"Second brother." Xiang Hui squatted down, put his head in front of Xiang Yang, and said with a flattering smile: "How much do you think this plain and light-colored krill is worth?"
Xiang Yang glanced at Xiang Hui, then shook his head and told the truth: "I don't know."
"Ah?" Xiang Hui asked in surprise, "Second brother, you can't estimate the price of these shrimps?"
Xiang Yang nodded. "Even though they are both plain-coated light-colored krill, their prices vary greatly. The size, transparency of the body, and the color of the head all affect the quality of the plain-coated light-colored krill."
"Even if the plain and light-colored krill are of the same quality, their prices vary greatly, because the lifespans of krill vary greatly."
"Krill that live in high latitudes have a very long lifespan. For example, those living in the North and South Poles can live for nearly ten years, or even more than ten years. Krill that live in mid-latitudes only have an average lifespan of two years, and those that live in low latitudes usually do not live more than a year. Krill that live in our latitude have a normal lifespan of only about six to eight months."
Xiang Hui opened his mouth and said, "So, my krill are worthless?"
Xiang Yang nodded, then shook his head. The main reason why ornamental fish are so valuable is that ornamental fish is an industry. As long as a fish can be sold at a higher price, it is worth buying back no matter how much it costs, because it is a commodity and can make a profit.
If every ornamental fish died in your hands not long after being bought, then ornamental fish would never form an industrial chain. Very few people would be willing to spend millions to buy a fish just for the sake of looking good.