When it comes to insects, perhaps we are already familiar with them. Colorful butterflies, bees visiting flowers and making nectar, silkworms spinning silk cocoons, singing cicadas, aggressive crickets, starry fireflies, agile dragonflies that look like airplanes, simple and cute little ladybugs , a mantis holding a pair of big knives with angry eyes, annoying flies, mosquitoes, cockroaches, etc. So, what other insects are there? Are silk-spinning spiders and stinging scorpions insects? What about millipedes and centipedes? You may not be able to fully answer these questions. Now let’s take a look at what kind of insects are considered insects?
Insects, like other organisms, have their own special classification position. It belongs to the class Insecta in the phylum Arthropoda in the animal kingdom. Its main features are as follows (imitation of Caiwanzhi picture):
(1) The links of the body are assembled to form three body segments: head, chest and abdomen;
(2) The head is The sensory and feeding center has mouthparts (mouth) and a pair of antennae, usually compound eyes and a single eye;
(3) The chest is the movement center, with 3 pairs of legs, and usually 2 pairs of wings ;
(4) The abdomen is the reproductive and metabolic center, which contains the genitals and most of the internal organs;
(5) During the growth and development of insects, they must go through a series of internal and external Only through morphological changes can they transform into adults. This change in body shape is called metamorphosis.
Therefore, the basic characteristics of insects can be summarized as follows: "The body has three segments: head, thorax and abdomen, 2 pairs of wings and 6 legs; 1 pair of antennae are born on the head, and the bones are wrapped outside the body; there are many shapes throughout life. Changes are spread all over the world. "
With the concept of insects, you now know the answer to the previous question: the bodies of spiders and scorpions are divided into two parts, the cephalothorax and abdomen, and there are 8 It has legs, so it's not an insect. Centipedes and millipedes have even more legs, with one or two pairs of legs on almost every link (segment), and of course they are not insects.
The Largest and Smallest Insects
In terms of weight, the heaviest insect in the world is the giant rhinoceros beetle of tropical America (Coleoptera, Rhinopteraidae). This rhinoceros beetle is 155 mm long from the protrusion of its head to the end of its abdomen, and its body is 100 mm wide, making it larger than the largest goose egg. Its weight is about 100 grams, which is equivalent to the weight of two eggs. In addition, a long beetle from Brazil (Coleoptera Cerambycidae) also has a body length of more than 150 mm. But in terms of body length, the longest insect is a stick insect living in the Malay Peninsula. Its body length is 270 mm, which is longer than a pencil.
The smallest and lightest insect in the world is Alaptus magnonimus Annandale, an egg wasp of the family Mymaridae, with a body length of only 0.21 mm and an extremely light weight of only 0.005 mg. Calculated, 200,000 eggs weigh only 1 gram, and 10 million eggs weigh as much as an egg.
How many species of insects are there in the world?
Recent research shows that there may be 10 million species of insects in the world, accounting for about half of all biological species on the earth. However, there are currently only 1 million named insect species, accounting for 2/3-3/4 of the known species in the animal kingdom. It can be seen that we still do not know 90% of the insect species in the world; according to the most conservative estimate, there are at least 3 million species of insects in the world, and there are still 2 million species waiting for us to discover, describe and name them. Currently, about 1,000 new insect species are published in the world every year, and they are included in "Zoological Record". Therefore, this magazine is a must-have search tool for researchers engaged in animal classification.
Among the named insects, there are 350,000 species of Coleoptera (beetles), among which the Curculionidae is the largest, including more than 60,000 species, which is 10 times that of mammals. Lepidoptera (butterflies and moths) follows, with about 200,000 species. There are about 150,000 species of Hymenoptera (bees, ants) and Diptera (mosquitoes, flies).
Not only are there many types of insects, but there are also many individuals of the same insect, and some individuals have an astonishingly large number. An ant colony can contain up to 500,000 individuals. A single tree can contain 100,000 aphids. In the forest, there can be 100,000 springtails per square meter.
When locusts occur in large numbers, the number of individuals can reach 700-1200 million, with a total weight of about 1250-3000 tons. The area covered by swarms can reach 500-1200 hectares, which can be said to cover the sky and the sun.
Tips on the naming and type specimens of organisms: Scientists give each organism they have studied but not recorded a Latin scientific name, which includes the genus name and the species name, which is called a double name. The method of naming was pioneered by the Swedish scientist Linnaeus in 1758. The specimens on which the name is based are called type specimens, one of which is designated as the holotype and the others as paratypes.
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Sociality:
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Solitary:
The vast majority of bees are solitary, that is, female bees build nests and collect pollen and store food alone. They have no "caste" differentiation. Each nest chamber is open, the inner wall is coated with wax and other moisture-proof materials, and enough bee food is stored in the chamber. The female bee lays eggs on the bee food and seals the nest. The larvae feed on bee food inside the nest. Most of the species that fall into this category are wild species, such as Glossidae, Geospermidae, Phytophthidae, Pseudomonas, Leafcutter and Striacedae.
There are some complex transitional types between sociality and solitaryness, and the genus Tunisia is the most prominent in this regard. However, there are also certain differences between different species. For example, the Marginalus wasp is a gregarious type, with social division of labor among individuals, and there are also slight differences in morphology (internal anatomy). Differences in external morphology and internal anatomy; soft tunnel bees have social buds: the overwintering female bees stay in the nest, and when the next generation of smaller female individuals (also called auxiliary bees) appear in mid-June, they interact with the auxiliary bees Build a new nest together and store bee food. However, the auxiliary bees do not mate and only lay unfertilized eggs that develop into males. In August, male and female offspring appear as large as the female bees, and the original female bees and auxiliary bees die one after another. The male bees die that year after mating, and the fertilized female bees overwinter again. The difference between this type of bees and typical social bees is that the female bee has prepared bee food before laying eggs