At the bottom of the sea

Cape sharks in the Gulf of Naples: up to 5 metres long but not dangerous to humans

Discovery by a team of researchers, researcher Noah: 'Encouraging presence for the gulf'

by Letizia Giostra

24 April 2026

3' min read

Translated by AI

Versione italiana

Key points

How the species looks
A 'lazy' and often accidentally caught shark
Other sightings in Sicily and Calabria

3' min read

Translated by AI

Versione italiana

It was in December last year when the remains of a cape shark were found near a quay in the port of Ischia. Several months later, a team of researchers from the Anton Dohrn Zoological Station identified in the waters of the Gulf of Naples a population of the same species.

A surprise not only for Neapolitans, but for the scholars themselves. This was reported by Simona Noè, lead author of the study. Previously only a few individuals had been observed, but as the researcher says, "we had no idea there were so many in such a small area". Accomplices are the coral reefs on the seabed that become a refuge for these sharks, deep bioconstructions located between the islands of Ischia and Capri.

The researchers' study

The research - funded by the National Biodiversity Future Center - used purpose-built underwater video systems equipped with bait to attract sharks (safely). The study was published in the journal Ecology and for project leader Trevor Willis, it represents an important moment in learning about the capabilities of this shark about which we currently 'still know very little'.

Reassuring the population is the author of the study, Simona Noè, who adds: 'The presence of such a large aggregation of these sharks in the vicinity of a large metropolitan area is encouraging for the ecosystem of the Gulf of Naples.

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How the species looks

It has a robust anatomy, a flattened head and a small dorsal fin that differs from the one that slices the surface of the water in two found in larger species. This is what the flathead shark looks like, one of the many names by which the Hexanchus griseus is called. The other names are bull dog shark, cow shark and six-gill shark.

Green-eyed and grey-bodied, during the growth phase it can reach very large dimensions. Its length varies between 1.5 and 4.80 metres, but documented cases speak of up to 5 metres.

A 'lazy' and often accidentally caught shark

Far from being a threat, because the flathead shark is known to be lazy, as evidenced by its way of swimming. It likes to be alone and stay at the bottom - usually between 200 and 1,000 metres deep - which is why it is difficult to detect its presence at the surface.

As for its taste in food, it prefers to eat small fish or crustaceans. Despite its size comparable to that of the white shark, it poses no danger to humans.

Although not targeted by hunters, it often happens that this shark ends up in longlines or entangled in nets due to its size. This is precisely why it is an endangered species.

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Other sightings in Sicily and Calabria

Its presence is widespread in many oceans, especially in temperate and tropical ones, including the Mediterranean Sea. It is easiest to find on theTyrrhenian side, there are not many sightings on the Adriatic side.

There have also been other sightings - as documented on social media - in the Sicilian and Calabrian coasts. It happens that the shark can reach the shore, but only because it is pushed by the currents. Images that have made the rounds on the net and have moved users to tears.

And then there is the case of the head shark found dead in Ischia, whose corpse was lying near the quay. According to initial investigations, the death was caused by injuries resulting from a previous capture.