Arrival of a seal shark on an Asturian beach generates great scientific expectation

Avilés. -A specimen of a Portuguese dogfish (Centroscymnus coelolepis) measuring 1.45 meters in length and weighing 18 kilos has been found stranded on the beach of Luarca, possibly due to the weakening of forces caused by a hook from which it managed to escape but which caused it to lose its way. The director of the Coordinator for the Study and Protection of Marine Species (Cepesma), Luis Laria, explained this Thursday to EFE that the discovery has caused a great impact on the scientific community because this species is quite unknown as it is usually found at great depths. The expert naturalist has assured that the finding has generated great scientific interest in different countries in the face of the necropsy performed, in addition to the media attention due to the physical appearance of this species.

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These sharks, which can reach up to 4,000 meters deep, are ovoviviparous, that is, they produce eggs, but these remain inside the mother's body until the embryo is fully developed. The eggs hatch inside the mother's womb and remain as fetuses within until they reach a size appropriate for expulsion and can have an independent life in their marine habitat. The team that performed the necropsy, which included Luis Laria, found twelve eggs, each seven centimeters in diameter: "Something spectacular because they are, let's say, embryos in formation, which would have been viable."

The specimen, found last week, did not present any type of anomaly that would help establish the causes of the stranding, but the necropsy has found the key in a bleeding tear that has made it think that it was a hook from which it tried to escape, although without preventing it from generating a hemorrhage that weakened it until it caused its death when it reached the beach.

Lives at great depth

These little-known specimens live several miles off the coast and are usually found at depths of between 400 and 1,600 meters. When they are in the gestation process, that depth is less, about 400 meters, to ensure the success of the breeding, seeking environmental suitability, away from abyssal pressures.

This animal with a robust body and dark color lives in the total darkness of the ocean and is able to perch on the bottom and remain there for much of its life, and for this, as was verified in the necropsy, it has a flat abdomen.

Laria explained that they don't need to make any respiratory effort, like any other shark if it were to rest on the seabed, thanks to spiracles they have on their head through which they absorb water to pass it to the gills, so they don't need to be with their mouths open.

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The specimen, 1.45 meters long - about 15 centimeters more than the known average - and weighing 18 kilos, has a liver that accounts for 27.8% of the total body weight. Once subjected to the conservation process, the specimen will be exhibited, along with its liver and eggs, in the Parque de la Vida directed by Luis Laria in Luarca.