We found 17 interesting facts about insects
The largest group of animals
The variety of insects is enormous. There are those whose sizes are indicated in micrometers, and those whose body length is greater than that of dogs or cats. Because they are one of the first animals to exist, they have adapted to live in almost any environment. Millions of years of evolution have separated them so much that they share only a few anatomical features.
1
Insects are invertebrates classified as arthropods.
They are the largest group of animals in the world and may make up up to 90% of this kingdom. More than a million species have been discovered so far, and there may still be 5 to 30 million undescribed species remaining.
2
They have several common anatomical features that make them easy to identify.
The body of each insect consists of three segments: head, thorax and abdomen. Their body is covered with chitinous armor. They move with three pairs of legs, have compound eyes and one pair of antennae.
3
The oldest insect fossils are 400 million years old.
The greatest flowering of insect diversity occurred in the Permian (299-252 million years ago). Unfortunately, the vast majority of species went extinct during the Permian extinction, the largest mass extinction ever to occur on Earth. The exact cause of the extinction is not known, but it is known that it lasted between 60 and 48 years. It must have been a very brutal process.
4
Insects that survived the end-Permian extinction event evolved during the Triassic (252–201 million years ago).
It was in the Triassic that all living orders of insects arose. Families of insects that exist today developed primarily during the Jurassic period (201 - 145 million years ago). In turn, representatives of the genera of modern insects began to appear during the extinction of the dinosaurs 66 million years ago. Many insects from this period are perfectly preserved in amber.
5
They live in a variety of environments.
Insects can be found in water, on land and in the air. Some live in feces, carrion or wood.
6
The sizes of insects vary greatly: from less than 2 mm to more than half a meter.
The record holder with a size of 62,4 cm is a representative of phasmids. This specimen can be admired at the Chinese Museum in Chengdu. Phasmids are among the largest insects on Earth. In contrast, the smallest insect is the parasitic dragonfly. Dicopomorpha ehmepterigi, the females of which (and they are more than half the size of the males) have a size of 550 microns (0,55 mm).
7
The size of living insects seems “just right” to us. If we went back in time about 285 million years, we might be shocked.
At that time, the Earth was inhabited by giant dragonfly-like insects, the largest of which was Meganeuropsis permian. This insect had a wingspan of 71 cm and a body length of 43 cm. The fossil specimen can be admired at the Museum of Comparative Zoology at Harvard University.
8
Insects breathe using tracheas, to which air is supplied through spiracles.
Tracheas are bulges in the walls of the insect's body, which then branch into a system of tubes located inside the body. At the ends of these tubes there are fluid-filled tracheoles through which gas exchange occurs.
9
All insects have compound eyes, but some may have additional simple eyes.
There can be a maximum of 3 of them, and these are the eyes, organs capable of recognizing the intensity of light, but unable to project an image.
10
The circulatory system of insects is open.
This means that they do not have veins, but the hemolymph (which functions as blood) is pumped through arteries into the body cavities (hemoceles) surrounding the internal organs. There, gas and nutrients are exchanged between the hemolymph and the organ.
11
Most insects reproduce sexually and by laying eggs.
They are fertilized internally using the external genitalia. The structure of the reproductive organs can vary greatly between species. The fertilized eggs are then laid by the female using an organ called the ovipositor.
12
There are also ovoviviparous insects.
Examples of such insects are the beetles Blaptica dubia and the flies Glossina palpalis (tsetse).
13
Some insects undergo incomplete metamorphosis and some undergo complete metamorphosis.
In case of incomplete metamorphosis, three stages of development are distinguished: egg, larva and imago (imago). Complete metamorphosis goes through four stages: egg, larva, pupa and adult. Complete metamorphosis occurs in hymenoptera, caddis flies, beetles, butterflies and flies.
14
Some insects have adapted to solitary life, others form huge communities, often hierarchical.
Dragonflies are most often solitary; beetles are less common. Insects that live in groups include bees, wasps, termites and ants.
15
None of the insects can kill a person with their bite, but this does not mean that such a bite will not be very painful.
The most poisonous insect is the ant Pogonomyrmex maricopa living in the southwestern United States and Mexico. Twelve bites from this ant can kill a two-kilogram rat. They are not fatal to humans, but their bite causes severe pain lasting up to four hours.
16
The most numerous insects are beetles.
To date, more than 400 40 species of these insects have been described, so they make up about 25% of all insects and 318% of all animals. The first beetles appeared on Earth between 299 and 350 million years ago.
17
In modern times (since 1500), at least 66 species of insects have become extinct.
Most of these extinct species lived on oceanic islands. The factors that pose the greatest threat to insects are artificial lighting, pesticides, urbanization and the introduction of invasive species.
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