The vast majority of Antarctic krill live in the surface layer shallower than 50 meters.
The esophagus of Antarctic krill can be seen to be green from its transparent shell, which shows that they mainly feed on phytoplankton, especially small diatoms (about 20 microns) . Diatoms are ground up by its gastric molars and digested in the hepatopancreas. Antarctic krill can also prey on copepods, amphipods and other small zooplankton. Its esophagus is a straight tube, and its digestive efficiency is not very high, so its feces still contain a lot of carbon.
In aquariums, Antarctic krill have been found to eat each other. When they are not fed in the aquarium, they shed their shells and shrink in size, something that other animals do not. This may be an adaptation to the limited food availability during the winter.
The water temperature in the Southern Ocean is low all year round, and the salinity does not change greatly. There is no interference from other factors such as rivers and rivers. Such a stable environment makes krill become delicate, have poor adaptability, and the environment is slightly You cannot adapt to changes. Adult krill are suitable for living in waters with higher temperature and lower salt content. Its suitable temperature range is only 0.64 degrees Celsius to 1.32 degrees Celsius. If the temperature exceeds 1.80 degrees Celsius, it may be fatal. Therefore, Antarctic krill are only suitable for living in the colder waters around Antarctica. There is no trace of Antarctic krill in the sea far away from Antarctica.
The main spawning season for Antarctic krill is from January to March, spawning on the continental shelf and in the upper areas of the deep ocean. As with all krill orders, the male attaches his sperm to the female's genital pore. For this purpose, the male's first abdominal limb serves as a mating tool. Females lay 6,000 to 10,000 eggs at a time. When these eggs are expelled through the genital pore, they are fertilized by sperm from the spermatheca attached thereto.
Based on the classic hypothesis based on data obtained from the British RSS Discovery, Antarctic krill eggs will grow as follows: 0.6 mm eggs sink to the bottom of the continental shelf or 2,000 to 3,000 meters in the ocean area When deep, gastrulation (the process by which an egg develops into an embryo) begins. When the eggs hatch, the first nauplii begins its ascent toward the sea surface, assisted by its three pairs of legs.
The next two larval stages, called secondary nauplii and metanauplii, are also fed by yolk. After three weeks, the young krill will complete their ascent. Their number can reach 2 per liter in waters 60 meters deep. When older, additional larval stages are called second and third thorax larvae and first to sixth thorax larvae. These stages are characterized by the growth and development of more legs, compound eyes, and setae. When about 15 mm in length, Antarctic krill begin to develop adult habits. They reach maturity in two to three years. Like other crustaceans, Antarctic krill must shed their shells to grow. About every 13 to 20 days, Antarctic krill sheds its chitinous exoskeleton.
The hatching of krill eggs takes place during the process of sinking (perhaps one or two thousand meters deeper). Specifically, after krill lay eggs, their eggs begin to sink, hatching as they sink. Krill eggs sink very quickly, sinking about 140 to 320 meters per day. After three to five days, it can sink to a depth of one to two thousand meters, and the hatching will be over at this time. After hatching, the krill undergo metamorphosis and move upward slowly. When they reach the 100-meter water layer, they have become young shrimps that can directly and actively feed. The total time from sinking to rising is three or four weeks.