Portal de Turismo de Castilla y León

We welcome you to the Crayfish House.

As in the rest of the park houses, thematic centres, and river education rooms spread throughout the Castilla y León region, this house is the recommended gateway to become familiarised with the fauna and flora of the area. At this centre, the educators will inform you about the importance of aquatic ecosystems and their preservation by getting to know a protected species such as the crayfish and learning about the practice of sustainable fishing. They will also help you plan your visit.

Here, information on emblematic species and habitats is provided to facilitate the identification and highlight the cultural and natural heritage of these places, in a respectful manner and promoting the conservation and appreciation of biodiversity and cultural heritage.

To access the crayfish house you can use the concrete ramp or the stairs on the opposite side.

You will reach a porch with metal columns in the centre. They display signs welcoming you and outlining what you will find in the House.

In this multi-purpose space you can learn about the ecosystems that make up our rivers through their flora and fauna, especially the secrets and biology of the native crayfish, and may carry out different environmental activities such as catching signal crayfish. At the end of the porch there is a footbridge that crosses the river and another that runs along the back of the house, parallel to the river.

If you stand in the middle of the walkway, you can observe the river as well as the nature growing there, including native birds and the animals living here.

If you walk around the building along the corridor parallel to the river, you can discover the house’s glass windows with pictures of different fish such as carp and trout, and the surrounding nature. You will also find pictures of a children's playground and the bird zoo on the other side of the river.

The Crayfish House is located in Herrera de Pisuerga.

Herrera de Pisuerga is a town in the province of Palencia. With an altitude of 844 metres above sea level, it has a population of about 1890 inhabitants.

It is popular for the archaeological site of the city of Pisoraca, Legio IV Macedonica, and its Crayfish Festival. It is renowned for the production of sausages, black pudding, preserves, and salted meats, as well as agriculture, especially the cultivation of beans. It is also part of the Northern Way of Saint James: The Besaya Route.

As you enter, you will find the green shop counter in the centre of the room and on the right-hand side the reception desk boasts a glass display case where you can get brochures with more information.

At the green shop counter you can buy key rings, stuffed toys, and souvenirs of your visit to the house.

The three types of crayfish that live in the river are also on display in transparent cylinder cases.

Behind the counter's panel you’ll find the Burejo crayfish game.

Look around the House for clues on how you can protect the native crayfish species. Answer the questions the game asks you and you will gain access to an important mission.

Now go around the green shop and head towards the back of the sign in the centre. On the right wall, you can find the lift to the upper floor or take the stairs, which are easily accessed from the left side.

Behind the panel, there is an interactive game with four screens featuring quizzes to clear the river of rubbish and catch some crayfish.

Upstairs, you can find an aquarium, a model to learn about the typical vegetation and some screens.

If you go up the stairs you will find the permanent exhibition hall on the left-hand side and the temporary exhibition hall on the right. If you go up on the lift, it will be the other way around, the permanent collection will be on your right and the temporary exhibition room will be on your left.

The temporary exhibition room is an event room where environmental education and nature workshops are held and exhibitions are organised.

Just before entering the permanent exhibition hall, you will find the toilets in a corridor on the right-hand side.

Cross the corridor and enter the permanent exhibition room.

As you enter, you will find a life-size model of trees and vegetation growing out of an aquarium.

The aquarium is divided into 3 sections corresponding to a river: The upper, middle, and lower sections. In each one, you can find different species natural to that area, but in all of them the crayfish are needed to feed on carrion and keep the waters clean.

In the lower area, you can get to know four species of fish that inhabit this stretch of the river: The Northern Iberian chub, the gobio, the tench, and the barbel.

The gobio is a small fish that exhibits a diverse range of colours and patterns. It is noted for its territorial behaviour and the construction of nests for its young. These fish play a vital role in aquatic ecosystems, contributing to the food chain by feeding on insects and small invertebrates, while being prey for larger fish. Their peculiarity and attractive colours also make them popular in aquaria.

In the middle stretch of the river, there are more fusiform species, shaped like a rifle, such as the bermeja or northern straight-mouth nase.

The northern straight-mouth nase is a medium-sized species that generally does not exceed 50 cm in total. It has a straight lower mouth opening, with a thick lower lip including a corneous lamina. Its body is usually pigmented with small black spots, being more noticeable in the populations of Portugal and Galicia.

In the upper stretch of the river, trout are an indicator of water quality.

Trout is a fish known for its elegance and value in sport fishing. Its elongated body is adorned with a characteristic colouring that varies according to species and habitat. Trout are known for their ability to live in cold, oxygenated waters, preferring fast-flowing streams and rivers. Equipped with a prominent mouth and sharp teeth, they are voracious predators that feed mainly on insects, crustaceans, and smaller fish.

Above the aquarium, there is riparian vegetation, typical of areas close to bodies of water such as rivers, streams, and lakes. These areas near the river banks play crucial roles in ecology, stabilising the soil through root networks that prevent erosion, filtering pollutants before they reach the water, providing vital habitats for various species, contributing to nutrient cycling, and helping in flood control by absorbing excess water.

Examples include:

Reeds, characterised by their cylindrical stems and narrow leaves, can grow up to 90 centimetres long. It usually flowers between April and June, with a small, brownish, compound flower, which later becomes an oval fruit, which is also brown. The reed's flexibility in colonising marshy areas has made it a plant valued for its ability to contribute to the health and biodiversity of aquatic ecosystems.

You can also find wild roses, a species of rose native to Europe, North Africa, and West Asia. This plant is distinguished by its white or pink flowers and its characteristic red fruits in the form of small berries, called "rose hips." Interestingly, these fruits are very rich in vitamin C and have traditionally been used in the preparation of herbal teas and syrups.

Large trees grow among the rose bushes, like hazels. The hazel tree is a deciduous tree, which can reach heights of up to 6 metres. It has a distinctive rough bark and serrated oval leaves. In addition to its fruit, the hazelnut, its wood has also been used historically to manufacture tools and handicrafts.

Next to it, an oak tree stands out. It is a majestic and long-lived tree, characterised by its robust trunk and lobed leaves. Oak trees can be centuries-old. They produce their characteristic fruits, acorns, which are an important source of food for different species of wildlife. In addition, oak is known for its durability and has been used in the construction of furniture and wine barrels.

Finally, if you look closely, on the dry branch of a bush, you may find a nest that a bird has built with twigs it found on the river bank.

All this riverside vegetation makes the riverbank an ideal habitat for a great diversity of animals.

The first animal that stands out on the model is an otter. The otter is a semi-aquatic mammal known for its graceful agility both in water and on dry land. They have dense fur and a muscular tail, making them expert swimmers in rivers, lakes, and estuaries. Their diet varies, but it commonly includes fish, crustaceans, and other small aquatic animals. Furthermore, their playful and social behaviour includes games and elaborate burrow building, thus adding a distinctive charm to their nature.

Next, on a rock, there is a green frog and, to one side, a marbled newt, both indicators of excellent water quality. Interestingly, newts have a unique ability to regenerate. If a newt were to lose any part of its body, such as a limb, it can regenerate it completely. Adults also produce toxins that are secreted through the skin as a defence mechanism against natural predators, such as snakes. This toxin only has an effect if ingested and not if you come into contact with the animal.

Similarly, the remains left behind by animals are valuable to scientists and naturalists, as they provide crucial information on the presence and behaviour of these species. These remains are a valuable tool for environmental education, allowing you to learn about wildlife and the interconnectedness of species within ecosystems. Thus, in the model, you can find several broken snail shells. This is due to the presence of the thrush, a bird that loves to feed on snails. To eat them, they pick the snails up with their beaks and beat them against a rock, like an anvil.

There are also some snake moults and crab shells, which are an indirect reflection of their passage through the area.

If you turn around, you will find information and interactive panels.

The first sign is held up by the silhouette of a white-clawed crayfish, and this is where its story begins.

Move on to the next panel showing a video of two crayfish mating at the bottom of the river.

In October and November, the male searches for the female using his senses of smell and sight. Using his larger claw span and forceps, he positions her ventrally and releases the sperm onto the underside of her abdomen, where it adheres. About a month later the female lays her eggs, which is then when the eggs become fertilised.

Crayfish biology is marked by sexual maturity, which is reached in the fourth year for females and in the third year for males. Three to four weeks may elapse depending on water temperature and the availability of nutrients in the environment between copulation and egg laying.

To your right is the following sign with a baby crayfish on top of an adult crayfish. Here is a video of a crayfish cleaning the water in which they live.

After hibernation, the female begins to unfold her tail and opens the sac where the eggs have been lodged all this time. Gradually, the eggs hatch and the larvae emerge, which in two weeks transform into small crayfish that look just like the adults, but miniature-sized.

The next poster shows a crayfish catching a fish with its pincers. A video of a crayfish feeding is projected on a screen.

Crabs are omnivorous; therefore, they eat aquatic plants, insects and amphibian larvae, small fish, and even the remains of decomposing animals, playing an important role in keeping the river bed clean. They also have their own cleaning service: Leeches.

Leeches are symbiotic animals that help keep them clean in exchange for transport and food. They range in size from a few centimetres to less than a millimetre, with an elongated, pear-shaped body.

On the next panel, another video is projected and there is a silhouette of a crayfish coming out of its shell.

The crayfish's outer shell, called the exoskeleton, becomes tighter as it the crayfish grows and has to be shed. It takes about two weeks to produce a new one, which hardens thanks to the calcium salts dissolved in the water. During the first year of life it may moult up to 8 times, while in adulthood it moults only 2 or 3 times a year.

These moults are done by all crabs at the same time in the same river and it is normal to find a stretch of the river full of moults. They eat these moults themselves, because it is a good source of calcium and to remove them from the river to prevent predators from discovering their habitat.

The next screen shows a video of a crayfish walking calmly along the river bottom, when it encounters danger, it gives its tail a swish and flees backwards.

Contrary to popular belief, crayfish do not walk backwards but forwards. The reverse gear is reserved for their escape tactics. When they feel threatened, they contract their tails and, with their powerful musculature, leap quickly away from danger.

In the last panel there is a crayfish clutching to it. There’s also a drawing of a crab under a stone, peaking out as if it were a cave. The screen shows a crayfish walking calmly along the bottom of the river until it reaches a stone, where it hides.

The crayfish's refuge is very small. It is usually a small shelter that they dig and shape with their claws, taking advantage of natural elements such as roots or stones. An area where it’s easy to build shelters favours an abundance of crayfish.

Turn around and advance to a panel in the middle of the room.

Samples of the three crayfish that live in the rivers of the area and their characteristics are exhibited here: The white-clawed or native crayfish, the red crayfish, and the signal crayfish.

In addition to the native crayfish, there are two other crayfish species, brought from North America, which have invaded the Iberian Peninsula's riverbeds. These exotic species have infected the native crayfish with a fungus-borne disease, which is fatal to the native crayfish, namely, the crab plague or aphanomycosis. The rapid expansion of these two invasive species, together with other important factors such as poaching, periods of drought, pollution, and the transformation of watercourses, have caused a radical change in the distribution of our crayfish. Their population has gone from being one of the key species in river ecosystems to being reduced to isolation in barely 30 years, become highly-threatened populations.

But the alteration of aquatic ecosystems does not only affect the native crayfish, but the entire ecosystem is losing biodiversity and degrades: Large numbers of insects disappear, amphibians and fish decline, and there’s also a decline in vegetation.

The two American crayfish species were imported due to the fact that they were more profitable. While the native crayfish only lays about 120 eggs, the American crayfish can lay more than twice as many. The people of this area have always lived from agriculture and crab fishing, which generated an economic fabric due to exports. This also led to the creation of a social structure.

The two American crayfish species, like the native crayfish, are scavengers in their native areas, but these rivers become too small for them and they begin to prey on other animals and move out into crops, such as rice fields, cornfields, and orchards.

On the panel is a display case featuring a native crayfish, showing its front and side.

This crustacean, also known as the white-clawed crayfish, has an olive hue with the underside varying from pale to red. It is around 10-12 centimetres long, and is characterised by its remarkable pincers, medium-sized antennae and 8 locomotor appendages. The cephalothorax is significantly larger than the abdomen, which accounts for half of the body, the first two parts being much bulkier.

This hard-shelled crayfish with protruding eyes is known as the "white-clawed" crayfish is a protected, non-fishable species, declared vulnerable by the International Union for Conservation of Nature.

Endemic to Europe, it is found in Spain, France, the British Isles, Ireland, southern Germany, Italy, Austria, Switzerland, Slovenia, Bosnia, and Croatia.

Their diet comprises different forms of organic matter, both animal and vegetable, alive or dead.

Breeding begins at three or four years of age and each female can lay up to 140 eggs.

Although it used to inhabit small to medium-sized riverbeds, ponds, canals, and man-made ponds, it is now restricted to isolated areas, mainly at the headwaters of river basins.

Another glass case with a red crayfish is displayed next to it.

As its name suggests, this crayfish tends to be predominantly red in colour, although it can also show greenish or brownish hues. On the back of the cephalothorax, it has two longitudinal grooves which may be joined or slightly separated. In its adult stage, its length varies between 5.5 and 12 cm and it is notable for having very spiny pincers.

This crayfish, considered an invasive alien species, can be fished and originates from the central and southern United States and north-western Mexico, with abundant populations in the Louisiana marshlands.

In Spain, it was introduced in 1974 in the Guadalquivir marshes, in Seville, for commercial purposes.

As for its diet, it has a considerable appetite and can reproduce from the age of three years, laying around 100 eggs.

This crayfish is common in shallow stretches of water with little movement, and favours soft substrates for burrowing refuges and shows good tolerance to oxygen scarcity.

The next display case shows a specimen of a signal crayfish.

This is the largest of the three crayfish, reaching a length of up to 15 centimetres. Its colouring is brown, which can have bluish or reddish hues. The ventral part of the body exhibits a deep blue colour, while the ventral side of the pincers has a characteristic reddish colour. These claws show a distinctive white spot, from which the name "signal" derives.

The signal crayfish, native to North America, is considered an invasive alien species and can be caught.

It was introduced into Spain in the provinces of Soria and Guadalajara between 1974 and 1975 for commercial purposes.

With a voracious appetite, this crayfish can consume a wide variety of foods, including other crayfish.

It starts breeding at the age of two years old, laying between 200 and 400 eggs.

The crayfish can inhabit a variety of habitats, from watercourses with rocky substrate and warm water to flat rivers and high mountain stretches.

Now, exit the Crayfish House by backtracking the entire route through this room until you reach the corridor and take the lift or the stairs. Once you’ve made it to the ground floor, in the reception room, go around the green shop and exit through the glass door.

Head towards the terrace parallel to the river.

From the terrace rise several small square balconies, also with railings, where you can cast a net and catch a crayfish.

For traditional crayfish fishing, a crab net is used, which is a net joined with two hoops to create a bag. In the centre of the base, a plate is placed with the bait, which is usually a ball of fishmeal.

This crab net is hooked to a stick, called a fork, or horcajilla in this village, and thrown into the river from one of the balconies. The next step is to wait for the crayfish to come to the plate to eat the bait and pull the crab net out of the water.

This audio track concludes the visit to the Crayfish House, where you have learned about the white-clawed crayfish, discovered where they live, what they eat, and what threatens their survival.

If you would like more details, you are welcome to come to the reception desk or speak to any of the educators at the House.

Thank you for your visit.