Index
This name is attributed to invertebrate animals that have an exoskeleton.
That is, the species that have a segmented body with a variety of jointed ones.
Among the living beings that present these characteristics are:
- Spiders
- Flies.
- Prawns
- Butterflies
Characteristics of Arthropods
There are approximately more than 10 million species that are within the group of Arthropods, which present diversity varieties of individual characteristics, however, among which can be called the most common among them are:
Segmentation of the extremities of the body: it is formed by a large number of metaseres, where various repeated modules are created.
This characteristic presents a phenomenon called tagmatization, which has as a differentiating point between the species that present it that the body is divided between two or three different parts.
Exoskeleton: it is a non-cellular material that in turn is called the cuticle, which is secreted by the epidermis and is characterized by enveloping the body segments together with small hairs that have different functions depending on the species. This cuticle is divided into three parts:
Epicuticle: is the one that permeabilizes the external part of the body segment.
Exocuticle: it is the thickest of the three and in turn presents great rigidity.
Endocuticle: it is thick but differs from the exocuticle due to its flexibility.
The species that are within the family of arthropods live a process known as ecdysis, which helps them to move from the exoskeleton because it does not grow as the animal develops over time, which would limit them in size and evolution.
The animal when undergoing this process spends a lot of energy and it is the moment that they are usually most vulnerable and can be attacked by their enemies or by species that feed on them.
Arthropods also have segmented internal organs, grouped together and repeated throughout their body, nervous systems, excreta systems and circulatory systems.
In the case of the circulatory system, it tends to have blood circulating freely through the body cavity of the body thanks to a condition called hemolymph.
Most of the species found in this family transport oxygen through a pigment and are possessed by various groups of invertebrates to survive, which is called hemocyanin.
To breathe in some cases they use different systems that have devices capable of connecting the external part of their body with the internal part to provide the oxygen that their body deserves.
The arthropods that live in the sea have the same mechanism as those that live on the earth’s surface, but what differentiates them is that they have gills and the other primitive lungs.
Depending on the species, their nervous system can be relatively complex, the usual thing is that they present two nerves that encompass or are responsible for the functioning of the body.
Also each segment of the body parts has a pair of ganglia. In the case of the brain, it can be formed or composed by the fusion of a variety of ganglia existing in the head.
Arthropods have several senses, but the one that most predominates as part of their survival, care and feeding is sight.
Their eyes can have multiple segments such as ommatidia that are found in various locations that allow them to have a very wide vision and detect things that a human being may not be able to easily detect.
Others may have a simpler and more limited vision, everything will depend on the species.
There are some arthropods whose most active sense are sensors that allow them to distinguish whether or not there is danger around them through tactile cables that generate chemical stimuli that help them distinguish the situations where they are.
Reproduction of Arthropods
Depending on the species, fertilization can be carried out in different ways, terrestrial animals usually carry out the fertilization process in the terrestrial environment in places separated from the rest of the same group of species.
In the case of maritime, they can do it externally, that is, out of the water or internally but excluded.
The common denominator of arthropods are oviparous, but there may be species that are not, such as scorpions, that are viviparous.
But some in their evolutionary process or physical development must first go through the larval stage.
Classification of Arteropods
Among this category of species can be subdivided as follows:
Trilobites: they were aquatic animals that became extinct in the Triassic period.
Quelicerates: in this category are spiders and scorpions. Physically they have a pair of appendages next to their mouths that allow them to feed.
Myriapods: they are known as a terrestrial group that have endless legs such as:
- Centipede.
- Milpies.
Crustaceans: they are species that live in the sea and are characterized by biramean extremities, meaning that they branch at two ends. Among this group are:
- Prawns
- Lobsters
- Crabs
Hexapods: they are those with six legs, such as:
- Flies.
- Bees
- Beetles
