A massive hammerhead shark has been sighted close to the Irish coast for the first ever time, scientists have revealed.
The predator, that has a distinctive hammer-shaped flattened head, was spotted in the Celtic Sea about 100 miles south west of Ireland.
Its appearance on the surface of the sea was fleeting but enough for two marine scientists to positively identify it.
The sighting comes a week after a marine expert predicted that some shark species such as the Great White and hammerheads could become regular visitors to Irish and British waters by 2050 due to rising sea temperatures.
Hammerheads, that can grow to 20ft in length, usually inhabit warm and tropical waters such as the Caribbean and West Africa and migrate to cooler seas in the summer.
Experts say the lone specimen could have been lost but probably ventured further north than normal due to the oceans getting warmer.
Its arrival could also make it more likely that a Great White shark may be seen in Irish waters in the near future.
The smooth hammerhead - sphyrna zygaena in Latin - was spotted during a survey of herring stocks in an area of the Celtic Sea by scientists from the Marine Institute based in Galway.
The survey is carried out every year on board the Marine Institute’s RV Celtic Explorer.
John Power, a marine mammal observer who spotted the hammerhead, said:
“While scanning the ocean surface, we sighted a dorsal fin unlike anything we had encountered before. It was quite different to the fins seen on basking sharks and blue sharks.
“After consulting available ID keys, we agreed that the shark must be a smooth hammerhead.”
Dr Paul Connolly, director of fisheries and ecosystems services at the Marine Institute said: “This is an exciting encounter, especially since a rare deep-water shark nursery, 200 miles west of Ireland, was discovered by Irish scientists last year.
“This sighting of a new shark species, shows the importance of our fishery surveys to monitor our marine environment, and to observe changes in our oceans and marine ecosystems.”
Dr Simon Boxall, of the Southampton Oceanography Institute in the UK, said there is no reason why hammerhead sharks could not exist in these waters.
He said: “I am not aware of them (hammerheads) being seen in our waters before but this sighting does not surprise me.
“Temperatures in these waters have increased by 2.5C over the last 20 years and more exotic species carried by the Gulf Stream are travelling further north for food.
“But this also means that native fish species such as cod are also being pushed further north as they lose colder waters.
“It could be a very lost hammerhead shark but more likely it is because our oceans are getting warmer.
“There is no reason why more shark species like hammerheads and Great Whites can’t exist in our waters.
“I am sure these species are more common than people realise, it’s just that they haven’t been seen.
“But it doesn’t mean we are going to get a mass invasion of hammerhead sharks.
“They are not particularly interested in humans and attacks on humans are rare. But they are more dangerous than a porbeagle shark which are native to UK waters.”
According to experts, there have been no known fatalities from hammerhead sharks anywhere in the world to date.
The species is listed as ‘vulnerable’ on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, and is being increasingly targeted for the shark fin trade.
