This kind of "shrimp" is poisonous, and blue whales can swallow a whole group of them in one bite

Review expert: Li Weiyang, well-known popular science writer

There is a golden moon hanging in the deep blue sky, and below it is the endless sea. On the dark blue sea, there are spots of silver light flashing continuously, which are the krill swimming in the sea.

Is krill a shrimp? The krill we usually refer to refers to the general term for animals of the order Euphausia under the subphylum Crustacea, including krill (genus Euphausia) and northern krill (genus Meganyctiphanes norvegica). Shrimp is a general term for animals of the order Decapoda under the subclass Soft Shells of the class Crustacea. The prawns and shrimps we often eat belong to the family Penaeidae under the order Decapoda, while the swamp shrimps belong to the family Longibridae under the order Decapoda. From this classification, it can be seen that prawns and shrimps are close relatives, while swamp shrimps are slightly more distantly related to them, and although krill has the word "shrimp" in its name, it is not a shrimp at all.

Source: Baidu Encyclopedia

Krill are marine creatures with light-emitting organs in their eyes and chests. So when groups of krill swim in the shallow sea at night, we can see the beautiful scenery of the sea surface glowing with silver light. There are a large number of beautiful krill (Euphausia superba) distributed in Antarctica, because the rising ocean currents here bring a large amount of algae, which provide rich food for krill. In my country, the more common is Pacific krill (Euphausia pacifica).

Source: otlibrary.com

Can krill be eaten? Krill can be eaten. In some places, krill is made into shrimp paste, shrimp balls, and shrimp intestines for consumption. From a nutritional point of view, krill is a very good food. First of all, krill has a high protein content and a low fat content, which is suitable for people who want to lose fat and gain muscle. Secondly, krill protein hydrolysates contain a variety of amino acids, including the 8 essential amino acids needed by the human body, such as lysine, and glutamic acid that provides umami taste, which is both nutritious and delicious. Thirdly, krill is rich in minerals, such as selenium. Finally, krill mainly feeds on algae and is at the bottom of the food chain, which largely avoids the enrichment of heavy metals.

Source of krill paste: a shopping website

In addition, krill oil extracted from krill is rich in EPA (eicosapentaenoic acid, which has the effect of lowering blood lipids and blood pressure) and DHA (docosahexaenoic acid, which has the effect of promoting the normal development of brain cells and retina in infants and young children), and has certain health benefits. The rich chitosan in krill shells can enhance immunity, lower cholesterol, blood pressure and blood sugar, etc., and krill are small in size and thin in shell, and the extraction process is relatively simple.

Although krill has all the above advantages as food, one problem that cannot be ignored is that krill, especially the shell, contains a lot of fluorine. After the krill die, under the action of endogenous enzymes, the krill will "autolyze", and the fluorine in the shell will penetrate into the shrimp meat, causing the fluorine content of the shrimp meat to increase. Therefore, freshly caught krill must be shelled in time.

Krill undergoes "autolysis"

Source: otlibrary.com

It must be pointed out that a safe dose of fluoride has a positive effect on the human body. For example, after the enamel absorbs fluoride, a protective layer will be formed on the surface of the teeth, which can reduce the damage to the teeth by acids and other corrosive substances. People also prevent tooth decay by using fluoride toothpaste or going to the hospital for fluoride application. However, if the fluoride content in the human body is too high (the urinary fluoride level of adults exceeds 1.6 mg/L, and the urinary fluoride level of children exceeds 1.4 mg/L), it will cause fluorosis. Fluoride poisoning can affect the human body's bones, nervous system, endocrine system, reproductive system, etc., causing osteoporosis, cognitive impairment and other problems.

What is the significance of krill to the biosphere? Krill is a tiny thing, but its significance to the biosphere is not small. Krill is the food of carnivorous animals such as penguins, whales, and seals, and plays a connecting role in the food chain of phytoplankton-krill-carnivorous animals. A photographer once took a picture of a blue whale preying on krill: the blue whale opened its bloody mouth and sucked in a large group of krill in one gulp. The number of krill was very impressive.

Krill's place in the food chain

Source: British Antarctic Survey

In the absence of external factors, this food chain can maintain a normal cycle. Later, due to factors such as global warming, people speculated that the number of krill would decrease, but the fact is just the opposite. Polar research scholars at the University of Science and Technology of China believe that this is because human fishing activities are frequent, and the number of krill's natural enemies, such as whales and seals, has decreased. However, there is a "krill paradox" in the scientific community, that is, in areas where whaling activities are particularly frequent, the number of krill has also decreased significantly. Scientists speculate that whale excrement provides nutrients for phytoplankton. Once the nutrients decrease, the phytoplankton will also decrease. Therefore, the krill that feed on phytoplankton will also decrease accordingly, but this speculation has not yet been confirmed.

Krill Swarm

Source: otlibrary.com

Will krill be the next hot food? At present, it is generally believed that krill is the future protein bank of mankind. It is estimated that the reserves of Antarctic krill are 600 to 1.2 billion tons. Since China's first Antarctic scientific expedition in 1984, we have launched a survey of Antarctic krill resources. In 2010, my country officially launched commercial fishing of krill. By 2014, my country's krill catch reached 54,000 tons. In addition to my country, Norway, Japan and other countries have long been eyeing krill resources, and some health products made from krill oil have been hyped. However, the size of krill is really difficult for people to feast on, and the fluorine content of the shrimp shell also adds to the difficulty of krill processing.

Krill Oil Soft Capsules

Source: A shopping website

All these situations seem to indicate that although krill is popular, it will take some time for it to enter the homes of ordinary people. However, with the continuous upgrading of technology, we will surely be able to fully and reasonably utilize krill resources and develop more value on the basis of protecting its ecological value.