Austropotamobius pallipes It is a type of decapod that is native to the European continent, mainly from the western area of the east, the Balkans, the Iberian Peninsula and part of the United Kingdom.
It is also known as the European crayfish and is classified as an endangered species. It was first described by the French zoologist Dominique Lereboullet in 1858.
The decline in the population of Austropotamobius pallipes It is due to several reasons. In the first place, the destruction of their natural habitats by human action, as well as indiscriminate fishing..
Likewise, this crab is the victim of an infection caused by fungi of the species Aphanomyces astaci, which infect it causing a disease known as aphanomycosis. Due to this, every day there are more campaigns that are developed in order to promote its conservation and preserve the natural sites in which it takes place..
The presence of this animal in rivers and lakes is, according to specialists, an indicator of the excellent quality of its waters, as well as the little contamination of these..
Austropotamobius pallipes it is an organism whose cells have a central structure known as the cell nucleus. Inside this is its genetic material (DNA) forming the chromosomes. Therefore, it can be said that it is a eukaryotic organism and it is also multicellular. The latter implies that it is made up of various types of cells, each one specialized in a specific function..
This animal is classified within the triblastics, since, during its embryonic development, it presents the three germ layers: ectoderm, mesoderm and endoderm. From these three layers the various tissues that make up the adult organism develop. Likewise, it is coelomed, since it has an internal cavity called coelom.
The European crayfish is a heterotrophic organism, so it requires feeding on other living beings or on substances made by others, since it does not have the ability to synthesize its own nutrients. In this sense, it is omnivorous because it feeds on both plants and animals..
It is an animal that is located mainly in bodies of fresh water, whose temperatures range between 8 ° C and 22 ° C. Above or below that interval, life for this animal is not possible.
They are dioecious, that is, there are female individuals and male individuals. They also reproduce sexually, their fertilization is external and their development is direct. In the following video you can see the morphology of this species:
As with all arthropods, the body of Austropotamobius pallipes It is divided into several regions: an anterior region known as the cephalothorax and a posterior region called the abdomen. The size of this animal is varied, however, specimens have been known to have reached 13 cm in length.
The body is covered by a kind of protective layer or cuticle, which is made up of chitin. It is quite resistant, although where the animal's segments meet, it becomes a thin membrane with a soft texture..
The cephalothorax occupies more than half of the body of the animal and is much more voluminous than the abdomen. The head and chest are separated by a fold or depression called the cervical sulcus..
A pair of antennae come out of the head, which are oriented forward. The function of these has to do with the maintenance of balance by the animal. It also has one pair of mandibles and two pairs of maxillae. All these appendages fulfill functions in the feeding process, specifically the ingestion of food..
Like all members of the Decapoda order, Austropotamobius pallipes it has a total of five pairs of legs, all arising from the cephalothorax. The first pair of legs is much more developed than the others. At their distal end they have a clamp-shaped structure, which helps to capture food. The function of the rest of the four pairs of legs is locomotion.
In the abdomen it presents five pairs of small appendages that, as a whole, are known as pleopods. The function of these is mainly swimming. However, in males, a pair of pleopods is modified forming what is known as a gonopod. This is the organ that the animal uses to transfer sperm to the female..
In the case of females, pleopods are very useful during the reproduction process, since they hold the fertilized eggs between them in order to comply with the incubation process..
The terminal part of the abdomen is called the telson and the anus of the animal is located there..
The taxonomic classification of the European crayfish is as follows:
-Species: Austrapotamobius pallipes.
Austropotamobius pallipes It is an animal found on the European continent, specifically on the Balkan Peninsula, the Iberian Peninsula and the islands that belong to the United Kingdom. In this last place is where they are found in greater quantity.
Now, as its name suggests, it is an animal that occupies freshwater habitats, such as rivers or streams, which are characterized by being shallow. It also prefers bodies of water in which the current does not have much speed..
This is a fairly versatile animal that has the ability to survive at various temperature levels..
According to the specialists who have had the opportunity to observe it in its natural habitat, the juvenile specimens prefer to be located in the places where there is a greater flow of water. On the contrary, the adult specimens prefer to be located further towards the bottom, where the current is much calmer..
In this habitat, the European crayfish is mainly found in places such as under rocks or in holes that it digs. It is also of rather nocturnal (or twilight) habits. This means that they spend most of the day hiding in their burrows or hiding places and when the sunlight diminishes they begin to come out, mainly to feed..
The European crayfish is a heterotrophic organism. Within this group, it is considered omnivorous, since it can feed on both plants and animals.
First of all, this crab feeds on aquatic plants and algae found where it lives. Likewise, it also feeds on small invertebrates such as flatworms, nematodes and even mollusks and other arthropods that are within its reach..
Likewise, it constitutes a predator for small amphibian larvae that require aquatic environments to develop. Small fish have also been included in their diet that can be ingested by this.
The digestive process of the crayfish is similar to that of other decapods. The capture of the food is done through the action of its appendages known as cheipeds. Likewise, the maxillipeds, which are also appendages, contribute to this process, and even more, they help to crumble the food so that digestion is easier.
Subsequently, with the help of the mandible and maxilla (oral appendages), the food is ingested and then passes into the oral cavity of the animal. From here, it is transported to the esophagus, and from there to the cardiac stomach.
This is where the food undergoes a great transformation, since it is subjected to the action of structures such as the gastrolite and the lateral and ventral teeth of the gastric mill. All of these contribute to the proper crushing and processing of the food to facilitate its absorption..
The food continues its transit through the digestive system of the animal and then passes to the pyloric stomach and intestine, which is where digestion will culminate. Here it is subjected to the action of various chemical substances known as digestive enzymes so that the nutrients are then absorbed.
As in any digestive process, there are always waste substances, which are released through the anus of the animal..
Crayfish reproduce sexually. This type of reproduction involves the exchange of genetic material through the fusion of sexual gametes (female and male)..
The process of reproduction of Austropotamobius pallipes It is quite complex, since it is made up of several stages, which include the mating rite, the coupling, a hibernation process, the fertilization of the eggs and their laying, the incubation of these and of course the birth of the young. In addition to this, the reproductive process of the European crayfish occurs at a specific time of the year: in the months of October and November..
When the time comes to start mating, the behavior of the males becomes violent and even between the male and the female there is a fighting process before mating occurs. This fight can be very intense and can even lead to injuries that cause the death of one of the two animals..
After the male and female have completed the mating ritual and it has already been established that fertilization will occur between them, the sexual orifices of both specimens increase in size, preparing to expel the sperm (in the case of the male ) and to receive it (in the case of the female).
However, a copulation process as such does not occur, since the male does not introduce any copulatory organ inside the female's body. What happens here is that both animals mate and the male proceeds to release the sperm in the vicinity of the female's genital orifice. When the sperm comes into contact with water, it changes its physical state and goes from a liquid to a solid state, fixing itself between the legs of the female.
As occurs during the hibernation of any other animal, in the crayfish, the female is totally isolated from any other specimen of the species. During this hibernation, the eggs undergo a maturation process, preparing to be fertilized by the sperm that has already been deposited by the male..
Once the eggs are fully mature, the female forms a kind of cavity with her tail, in which she releases a substance whose function is to dissolve the sperm so that they can fertilize the eggs, which have also been released. to that cavity. The eggs remain attached by a kind of membrane and are attached to the body of the female.
This is a process that takes approximately five months. During it, the eggs remain fixed to the abdomen of the female and this is kept hidden to go unnoticed by predators.
After the incubation time has elapsed, the eggs hatch. From these emerges an individual that has the characteristics of an adult crab, but of a much smaller size. This happens in the month of April.
This individual will experience, throughout his life, several molts, at the end of each one his size will be increased. Sexual maturity is reached in the fourth summer after birth, approximately.