The Pyrenean desman (Galemys pyrenaicus), also known as the Iberian desman or trumpet rat, is a species of small semiaquatic mammal in the family Talpidae. It is endemic to the mountain ranges of the Pyrenees and to mountainous areas of the northwestern Iberian Peninsula, primarily the Cantabrian Mountains and the Sistema Central. Its distribution includes four European countries: Andorra, Spain, France, and Portugal. The species is closely related to the Russian desman.
The Pyrenean desman shows anatomical features that resemble those of several other mammals, including the brown rat (notably a robust tail adapted for swimming), the European mole (with strong, clawed forelimbs and a sensitive snout), and the common shrew (with an elongated snout used to capture small arthropods). The distinctive trunk-like snout gives rise to the alternative name "trumpet rat". The species has very limited vision and relies primarily on a highly developed sense of touch for orientation and foraging. Its mobile, prehensile snout bears vibrissae at the base and Eimer's organs at the tip, specialized tactile structures.
The desman is an insectivorous semi-aquatic species that inhabits mountain lakes and fast-flowing streams with clear water. Its diet consists mainly of aquatic larvae that are sensitive to pollution, including larvae of stoneflies, caddisflies, and mayflies. The species is primarily nocturnal and avoids human presence, which makes direct observation difficult. Several aspects of its biology, including details of its reproductive cycle, remain insufficiently documented.
The Pyrenean desman is restricted to unaltered and unpolluted watercourses and is therefore considered a reliable bioindicator of aquatic environmental quality. It is particularly sensitive to anthropization of its habitat: the construction of dams, the armouring of riverbanks with rock, and the building of barrages lead to habitat loss and fragmentation. Since 2021, the species has been classified as Endangered by the International Union for Conservation of Nature across its entire range, with populations continuing to decline despite conservation measures implemented since the early 21st century.
Historically, the desman was often regarded as a pest by local communities, particularly by fishermen and fish farmers, largely due to limited understanding of its ecology and diet. From the 1990s onward, this perception began to change as scientific research increased. In the early 21st century, the species occupies a paradoxical position: although it remains little known to the general public and faces a high risk of extinction, it has become an emblematic animal of the Pyrenean region and appears with increasing frequency in regional cultural expressions.
Description General anatomy
The Pyrenean desman measures approximately in total length, more than half of which is accounted for by the tail, and has a body mass of 50 to . There is no pronounced sexual dimorphism; females are on average slightly larger than males. Reliable sex determination generally requires close examination of the external genitalia.
The species has webbed hind feet, a relatively uncommon adaptation among insectivorous mammals, which is one of the characteristics supporting its placement in a monotypic genus. The genus Galemys includes only this single species. Comparable adaptations are otherwise found only in Limnogale, the Ruwenzori otter shrew, and the elegant water shrew.
In other respects, the morphology of the Pyrenean desman combines features found in several more familiar mammals:
from the brown rat, it shares robust hindquarters, well-developed thighs, and a long, thick tail that facilitates locomotion in aquatic environments; from moles, it has powerful, clawed forelimbs adapted for digging burrows used for shelter and rearing young, as well as a snout with a highly developed tactile capacity; from the common shrew, it shows a prehensile trunk and prominent vibrissae, which are used to detect prey larvae and to orient within its surroundings.
The dentition comprises , arranged according to the dental formula 3.1.4.3 in both the upper and lower jaws. This complete dentition corresponds to that observed in European moles. The two anterior upper incisors are particularly developed. The first premolar, considered supernumerary, is interpreted as a deciduous tooth that has become permanent.
Adaptations
On land, the Pyrenean desman has a rounded, stocky body. The fur is grey-brown, with silvery reflections on the underside and a tawny coloration in the pectoral region. The hairs are arranged in small tufts that can give a scaly appearance. Regular grooming with an oily secretion produced by abdominal glands ensures a high degree of waterproofing. The fur is therefore well adapted to an aquatic lifestyle and underwater diving. It is composed of two layers: a dense, silky underfur that remains dry, and an outer layer of long, flattened guard hairs of varying length. When submerged, this structure forms a smooth surface that retains body heat by trapping a layer of insulating air. This trapped air also increases buoyancy, in accordance with Archimedes' principle, requiring the animal to remain in constant motion underwater to avoid surfacing, which increases energy expenditure and partially offsets the insulating effect.
In water, which constitutes its primary habitat, the body assumes a streamlined profile. The forelimbs are held close to the body, while the robust, webbed hind feet are spread at an angle of about 45 degrees and function as paddles; they are equipped with sharp claws that facilitate gripping onto rocks. During dives, which typically last around twenty seconds, valves close the nostrils. The Pyrenean desman is an agile and powerful swimmer, capable of rapid movement in water and of swimming upstream, including at the surface.
The eyes are visible but partly concealed by the fur. As in most members of the family Talpidae, vision is poorly developed, and the animal is able to distinguish little more than variations in light intensity. The ears lack external pinnae and are entirely hidden beneath the fur, consisting only of a circular opening measuring approximately in diameter.
The tail extends from the posterior of the body and is broad at the base, gradually tapering toward the tip, which bears a small tuft of white hairs. At the base of the tail and on the ventral surface are two musk glands, whose swelling is readily apparent.
Trunk At the anterior end of the body is the desman's most distinctive structure: an enlarged proboscis that is hairy at the base and otherwise bare, measuring about in length and accounting for roughly one quarter of the animal's body length. This proboscis is flexible and prehensile, and divides distally into two lobes that contain the nostrils. As in the elephant, it results from the evolutionary fusion of the nose and the upper lip.
The proboscis constitutes the desman's principal sensory organ and, like that of moles, is among the most highly specialized tactile structures in mammals. It is used to detect prey underwater and to explore both aquatic and terrestrial environments. Sensory perception is mediated, first, by vibrissae at the base of the proboscis, which detect nearby and distant vibrations and movements. Second, the terminal lobes are covered with hundreds of thousands of Eimer's organs, whose high sensitivity enables the detection of prey within stream substrates. In addition, the vomeronasal organ (Jacobson's organ) is thought to contribute to the chemical detection of prey. This organ is located at the entrance of the nasal cavities, which communicate with the oral cavity via the palate. Its development is associated with a highly sensitive sense of smell, allowing the detection of larvae at distances of up to underwater. The vomeronasal organ is the sole olfactory system in fish and amphibians and is also present during embryonic development in mammals, including humans; in most mammals, its function is reduced after birth as olfactory perception becomes primarily mediated by the nasal conchae located deeper within the nasal cavities.
Cognitive abilities Scientific studies indicate that the Pyrenean desman exhibits well-developed spatial memory and orientation abilities relative to other mammals of comparable size. Individuals are able to retain information about the geometry of frequently used paths, as well as the olfactory and gustatory characteristics of their home range. Post-mortem examinations have shown that the cerebellum, a brain region involved in spatial coordination and orientation, is proportionally well developed in this species when compared with many other mammals. In particular, the cerebellum of the Pyrenean desman is larger than that of the mole or the Russian desman and, in proportional terms, is approached only by that of cetaceans.
Experimental observations further suggest that the desman is capable of discriminating, through tactile perception, between geometric forms, surface textures, and degrees of granularity. It can also recognize familiar shapes when they are rotated or presented from different orientations. These abilities imply the integration of tactile sensitivity with higher-order cognitive functions, including memory, three-dimensional shape processing, and spatial orientation.
Feces The feces of the Pyrenean desman are distinctive in appearance. They consist of small, twisted cylindrical pellets measuring approximately in length, with an oily texture and a colour ranging from dark green to black. They also emit a musky odour that is generally not readily identifiable by the human sense of smell.
Feces are most commonly deposited on rocks above the waterline. They act as a substrate for secretions from the musk glands and are thought to play a role in territorial marking and in the exchange of information between individuals.
Habitat and distribution Geographic range
The Pyrenean desman is an endemic species of mountainous regions of the Pyrenees, the Cantabrian Mountains, and the Iberian Sistema Central. It occurs primarily along specific rivers and their tributaries (listed from north to south and from west to east):
France: Nivelle, Nive, Gave d'Aspe, Gave d'Ossau, Adour, Neste, Pique, Garonne, Hers-Vif, Salat, Arize, Ariège, Aude, , Agly, Têt, and Techhttp://www.aude.gouv.fr/IMG/pdf/FR9101468-Bassin_du_rebenty_cle23a979.pdf Fiche de Synthèse Natura 2000 FR9101468 - Bassin du Rébenty.; Spain: Bidasoa, Leitzaran, Deba, , Lea, , Oka, Auritz, Irati, Aragon, Gállego, sierra de Guara, Ara, Cinca, Noguera Ribagorçana, Noguera Pallaresa, Segre, Ter, Oviedo, Pisuerga, Xallas, Tambre, Lérez, , Sil, Tâmega, Arandilla, Duero; Portugal: Minho, , Lima, Neiva, Cávado River, Ave, , Douro, Vouga, Mondego, Zêzere.
Many of these rivers are separated by continental divides or belong to distinct and non-contiguous drainage basins; as a result, the species' distribution is highly fragmented.
At a broad scale, the current range is considered a remnant of post-glacial expansion into newly available habitats, facilitated by terrestrial corridors and possibly a denser river network during the Holocene. At a finer scale, however, movements between neighbouring drainage basins may have occurred more recently. Habitat type