AUSTROPOTAMOBIUS PALLIPES: CHARACTERISTICS, HABITAT AND REPRODUCTION - BIOLOGY - 2025

Austropotamobius pallipes 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.

Specimen of Austropotamobius pallipes. Source: Chucholl, Ch.

The decline in the Austropotamobius pallipes population is due to several reasons. In the first place to 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.

General characteristics

-Species: Austrapotamobius pallipes.

Habitat and distribution

Austropotamobius pallipes 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. It is in the latter place that they are found in greater numbers.

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.

Austropotamobius pallipes in its natural habitat. Source: David Perez

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, 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.

Feeding

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 that are 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 that can be ingested by it have also been included in their diet.

Digestion

The digestive process of the crayfish is similar to that of other decapods. The capture of 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 these contribute to the proper grinding 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.

Reproduction

River crabs reproduce sexually. This type of reproduction involves the exchange of genetic material through the fusion of sexual gametes (female and male).

The reproduction process of Austropotamobius pallipes 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.

Mating ritual

When it comes time 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.

Coupling

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 liquid to solid, fixing itself between the legs of the female.

Hibernation

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.

Fertilization

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.

Incubation

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.

Birth

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.

References

1. Bernardo, J., Ilhéu, M. and Costa, A. (1997). Distribution, population structure and conservation of Austropotamobius pallipes in Portugal. Bulletin Français de la Pêche et de la Pisciculture. 347 (347)
2. Brusca, RC & Brusca, GJ, (2005). Invertebrates, 2nd edition. McGraw-Hill-Interamericana, Madrid
3. Curtis, H., Barnes, S., Schneck, A. and Massarini, A. (2008). Biology. Editorial Médica Panamericana. 7th edition.
4. Fureder, L. and Reynolds, J. (2003). Is Austropotamobius pallipes a good bioindicator ?. Bulletin Français de la Pêche et de la Pisciculture. 370
5. Hickman, CP, Roberts, LS, Larson, A., Ober, WC, & Garrison, C. (2001). Integrated principles of zoology (Vol. 15). McGraw-Hill.
6. Sweeney, N. and Sweeney, P. (2017). Expansion of the white- clawed - Crayfish (Austropotamobius pallipes) population in Munster Blackwater. Irish Naturalist's Journal. 35 (2)