Those who have visited the beaches of the Galician archipelago in recent days have encountered a scene that seems straight out of an extreme nature documentary. For the third time this year, the Cíes Islands have awakened covered in thousands of specimens of a crustacean species that tints the coastal areas and rocks a unique hue, creating a visual impact that has not gone unnoticed by visitors or the managers of the National Park.
This species, known locally by many names such as patexo, patelo, or even patulate, is actually Polybius henslowii. Although its formal name in Spanish is crab patudo, it is its Galician name that resonates most strongly in the ports and beaches of the area, making it clear that it is a familiar sight on our coasts. Despite not being a new phenomenon, it continues to surprise with the sheer number of individuals that the tides deposit on the shore.
What factors explain these massive landings?
The Maritime-Terrestrial National Park of the Atlantic Islands of Galicia clarifies that there is no single culprit, but rather a combination of circumstances that drive these animals to a dry end. One of the key factors is the increase in sea surface temperature , which, combined with persistent northerly winds during the spring and summer months, makes it easier for these crustacean shoals to be inevitably swept towards the coastline.
Unlike other members of its species that prefer to remain still on the seabed, the common stingray is an excellent open-ocean swimmer. However, its body structure is quite light and fragile, making it vulnerable to strong currents . When they travel in large pelagic groups, a change in oceanographic conditions is enough to leave them stranded on beaches, unable to fight against the force of the waves that deposit them on the sand.
An essential pillar for the marine ecosystem
Although seeing so many dead or dying animals on the shore might give a negative impression, the truth is that their role in nature is vital. These crabs are, so to speak, a veritable all-you-can-eat buffet for the local wildlife and are part of various ecosystems. marine species and their conservation in SpainFor species de peces as sea bass, bream or maragotasEncountering a bank of patexus is an unparalleled feeding opportunity that guarantees their development.
It's not just fish that benefit from this situation. Seabirds, such as gulls and cormorants, depend heavily on this resource, especially during their breeding season . In fact, it's very common for sailors to locate schools of this crustacean offshore simply by observing where flocks of birds congregate to feed, making it a natural biological indicator of the health of our waters.
From traditional agriculture to modern fishing
The Galicians' relationship with the cod goes back a long way and has evolved over the decades. In the past, since it had no market at the fish markets, it was common to see it harvested in large quantities to be used as natural fertilizer in farmland . Some even remember its use in traditional cooking, where it was used to give an intense, briny flavor to broths and stews, despite not being a particularly meaty species.
Today, its fortunes have changed, and it has become a coveted prize for anglers. It is considered a top-quality bait in both sport and professional fishing, highly valued for its effectiveness in attracting good-sized fish. As a curious detail, its scientific name, Polybius henslowii, is a small tribute to John Stevens Henslow, a professor of botany and a key figure in the education of Charles Darwin himself.
This recurring arrival of crustaceans to the Cíes Islands is a reminder of the profound connection between climate, ocean currents, and the life cycles of the species that inhabit the Atlantic coast. While the sight of the shore covered in these small swimmers may be visually striking, the phenomenon is part of a natural balance that nourishes Galician biodiversity and sustains essential ecological processes that have defined the richness of these waters for centuries.