The dragonfly larva is called a water scorpion. How fierce is it? It hunts like an alien

If there was a ditch or a stream near your home during your childhood, then a creature living in the water must have been your childhood nightmare: the water scorpion.

In fact, when we were children, most of us didn't know what this aquatic insect was called, let alone its origin. We only knew that it was ugly and extremely ferocious, and looked like a poisonous insect, but in fact this aquatic insect was the larva of an insect, and this insect happened to be one of our favorite insects in childhood: the dragonfly. The dragonfly is an ancient insect that has existed on Earth for hundreds of millions of years. During the Carboniferous period, because the oxygen content in the Earth's atmosphere reached 35%, the size of insects was much larger than it is now. It was during this period that the giant dragonfly with a wingspan of about 0.7 meters was born.

The giant dragonflies of the Carboniferous period were undoubtedly the overlords of the air, and although today's dragonflies are much smaller than their ancestors, their ferocious temperament has not changed.

Dragonflies are typical carnivorous insects. Flies, mosquitoes, butterflies, moths, etc. are all on the dragonfly's menu. It is precisely because of this that dragonflies are regarded as beneficial insects by humans, because most of their menus are harmful to humans. The dragonfly's vast food range and ferocious nature are entirely due to its superb flying skills. A dragonfly can switch from high-speed flight to hovering at any time, and can also start high-speed flight from hovering at any time. It can achieve translation in all directions without changing direction. In terms of speed and endurance, dragonflies can definitely be ranked in the first echelon of the flying world. Its flying speed can reach 50 kilometers per hour, and some species of dragonflies can achieve 5,000 kilometers of non-stop flight.

The dragonfly is a typical insect with incomplete metamorphosis. It goes through several different stages from egg to adult, and it also has to molt about seventeen times to become the appearance we are familiar with.

However, the adult stage of dragonflies only accounts for about 5% of the entire life cycle of a dragonfly. A dragonfly spends most of its time in the larval stage, and the larval stage is called a "water scorpion". The larvae of most insects are weaker than the adults, but the water scorpion is not like that. In terms of ferocity, the water scorpion is even far superior to its adult form. The water scorpion lives in water, and is almost invincible when it comes to similar body sizes. It not only feeds on the larvae of other insects, including mosquitoes, but also preys on small fish and shrimp in the water. In short, it eats anything that is of similar size to it.

Speaking of ferocity, tadpoles are considered to be relatively ferocious aquatic creatures. They will even eat each other. However, such ferocious and strong aquatic creatures are also on the diet of water scorpions.

The ferocity of the water scorpion lies not only in its vast food range, but also in its hunting method. The water scorpion lurks in the water, using its tentacles and legs to sense changes in the surrounding water pressure. When the hunting opportunity comes, it will suddenly pop out an organ called a "facial cover" from under its head to clamp the prey, and then quickly retract it and feed it into the mouthparts to eat. The facial cover is the hunting organ of the water scorpion, and its ejection speed is astonishing. The whole process only takes three hundredths of a second to complete, so we can't see what is happening with the naked eye. If we use slow motion, we will find that the hunting method of the water scorpion is very similar to the alien in the movie, except that the alien's mouthparts pop out from the mouth, and the water scorpion pops out from under the head.

How can the water scorpion's face flap pop out so quickly? It is achieved by the high pressure in the body.

Most creatures on land breathe through their lungs, and fish in water breathe through their gills. Insects breathe in a relatively special way. They breathe through valves all over their bodies. This breathing method is extremely sensitive to the oxygen content in the air, so when the oxygen content in the atmosphere increases, the size of the insects will also increase. So how do water scorpions, as insect larvae, breathe in the water? There is a respiratory organ called "tracheal gills" in the abdomen of water scorpions. Because it is located in the rectum at the rear end of the digestive tract, it is also called rectal gills.

The rectal gills can obtain dissolved oxygen from the water entering the rectum. The rectum is connected to the tail, so in a sense, water scorpions use their buttocks to breathe.

The body structure of the water scorpion can be used not only for breathing, but also for hunting. When the water scorpion is about to attack, it will close the water outlet at the tail and then violently contract its abdomen. In this way, an instantaneous high pressure is formed in the body, and under the action of high pressure, the face cover can be quickly ejected. The water scorpion has a large appetite. A water scorpion will eat about ten small fish or shrimps a day. They will live in the water for 2-3 years before they can emerge as dragonflies. Therefore, although the water scorpion also preys on mosquito larvae, it is usually regarded as a pest, especially in aquaculture areas. The proliferation of water scorpions will bring great economic losses.

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