Arthropods correspond to the most numerous phylum within the animal kingdom, so that most of the species on the planet are invertebrates. Within this group we find the subphylum of the Chelicerates, in which their first two appendages have been modified to form structures known as chelicerae (mouthparts), in addition, they present a pair of pedipalps (second appendages), four pairs of legs and no they have antennae. The Chelicerates are made up of three classes and one of them is the Arachnida, which in turn is subdivided into several orders, one being the Araneae, which according to the world catalog of spiders is made up of 128 families and 49.234 species.
The spiders are then a considerably numerous group. It is estimated, for example, that more than 1,000 individuals can be found in a space of 1 acre of vegetation. Spiders are usually related to insects, so on our site we have brought you this article to clarify the following question: Are spiders insects? We'll find out next.
General characteristics of spiders
Before going on to answer the question of whether the spider is an insect or not, let's get to know these peculiar animals a little better.
Parts of the spider
The body of the spiders is compact and its head is not visible, as in other groups. For its part, the spider's body is divided into two tagmas or regions: the former is called the prosoma and the latter opisthosoma or abdomen. The tagmata are joined by a structure known as a pedicel, which gives spiders flexibility so they can move their abdomens in various directions.
- Prosoma: the six pairs of appendages that these animals have are located in the prosoma. First, the chelicerae, provided with terminal nails, which are equipped with ducts with poisonous glands in almost all species. Then the pedipalps are located and, although they are similar to a pair of legs, they do not have a locomotive function, since they do not reach the ground; their purpose rather has a chewing base and, in some species of males, they use them for courtship and as a copulatory apparatus. Finally, the four pairs of locomotive legs are inserted, which are articulated appendages, made up of seven pieces. In the prosoma we also find the eyes, which are simple in this group, which is why they are also known as ocelli, turning out to be small photoreceptor structures for the animal's vision.
- Opistosoma: in the opisthosoma or abdomen, in general, are the digestive glands, the excretory system, the glands for silk production, book lungs, and the genital tract, among other structures.
Feeding
Spiders are carnivorous predators, they hunt their prey directly by running after it or by trapping it in their webs of silk or cobwebs. Once the animal is captured, they inoculate it with the poison, which has a paralyzing function. Then they inject some enzymes specialized in carrying out an external digestion of the animal, to later proceed to suck out the broth or porridge that has formed from the captured animal.
Size
Spiders, being such a diverse group, can come in a wide variety of sizes, ranging from a few centimeters to considerably large individuals of about 30 cm.
Poison
With the exception of the Uloboridae family, they all have the ability to inoculate poison However, for the great diversity of species that exist, only a few can be really harmful to humans due to the action of powerful poisons, which in some cases even cause death. Specifically the spiders of the Atrax and Hadronyche genera turn out to be the most poisonous for people. In this other article we talk about the types of poisonous spiders that exist.
What kind of animal is a spider?
As we have mentioned, the spider is an arthropod that is located in the subphylum Chelicerates, class Arachnida, order Araneae and has more than 100 families and about 4.000 subgenres. In this sense, spiders are not insects, since these are taxonomically located in the subphylum Unirrameous and in the class Insecta, so that although they are closely related Far away, the common feature that spiders and insects have is that they belong to the same phylum: Arthropoda.
Like insects, spiders are abundant on all continents except Antarctica. They are present in a wide variety of ecosystems, including some species that make aquatic life, thanks to the creation of nests with air pockets. They are also found in dry and humid climates, and their distribution range goes from sea level to considerable heights.
But spiders and insects have a close trophic relationship, since insects are the main food of spiders. In fact, this group of arachnids are biological controllers of insects, to the point of being essential to keep their populations stable, since they have highly effective strategies to reproduce, so there are millions of them in the world, as we explained. in this other article on How do spiders reproduce? In this sense, there are many spiders that are totally harmless to people and that help in an important way to control the presence of insects in urban areas, such as in our homes.
Examples of some spider species
Here are some examples of spiders:
- Goliath Tarantula (Theraphosa blondi).
- Giant hunting spider (Heteropoda maxima).
- Red-knee tarantula (Brachypelma smithi).
- Osprey spider (Dolomedes fimbriatus).
- Jumping spider (Phidippus audax).
- Funnel spider (Hadronyche modesta).
- Sydney spider (Atrax robustus).
- Blue Tarantula (Birupes simoroxigorum).
- Long-legged spider (Pholcus phalangioides).
- Closet spider (Steatoda grossa).
- Southern Black Widow (Latrodectus mactans).
- Crab spider (Misumena vatia).
- Tiger spider (Argiope bruennichi).
- Bull spider (Macrothele calpeiana).
- Fiddler Spider (Loxosceles Laeta).
A fear of spiders has long been widespread. However, these almost always have a shy and elusive behavior, when they attack a person it is because they feel threatened or to protect their offspring. Accidents with these animals are not usually fatal but, as we have mentioned, there are dangerous species that can cause death in humans. On the other hand, arachnids do not escape being victims of anthropogenic impact. Insecticides used on a large scale end up affecting them considerably, reducing their population stability.
An illegal trade has also been developing in some species, such as certain tarantulas, which have striking features and are kept in captivity as pets, an improper act, since these are wild animals that should not be kept captive. It is important to bear in mind that animal diversity with its particular beauty and its exotic species are part of nature that must be contemplated and protected, never mistreated or plundered
