Tourists have been banned from going into the water along an entire seven-mile stretch of Spain‘s Costa Blanca because of rare sea creatures with a potentially-fatal sting.

Reg flags went up on beaches in the municipality of Guardamar del Segura just north of Torrevieja following the appearance of so-called blue dragons, which have been branded ‘the most beautiful killer in the ocean’.

The sea slug, also known as Glaucus atlanticus, feeds on the venomous cells of creatures like the deadly Portuguese man o’war, storing them within its body in concentrated doses.

This process concentrates the toxin, making the blue dragon’s poison far more potent than that of its prey. If someone handles or steps on a blue dragon, it can release these stinging cells into the skin.

Typical symptoms of the blue dragon’s sting include nausea, pain, vomiting and, in some cases, dangerous allergic reactions.

While most stings are not deadly, they can be fatal for people with severe allergies, children or people with heart/respiratory conditions, and someone who has been stung multiple times.

Guardamar del Segura’s mayor Jose Luis Saez, confirming the sea ban order yesterday which he indicated would remain in place until further notice, said on his official X account: ‘Red flag on the beaches of Guardamar.

Tourists have been banned from going into the water along an entire seven-mile stretch of Spain's Costa Blanca because of rare sea creatures with a potentially-fatal sting

Tourists have been banned from going into the water along an entire seven-mile stretch of Spain’s Costa Blanca because of rare sea creatures with a potentially-fatal sting

Reg flags went up on beaches in the municipality of Guardamar del Segura just north of Torrevieja following the appearance of so-called blue dragons, which have been branded 'the most beatiful killer in the ocean'

Reg flags went up on beaches in the municipality of Guardamar del Segura just north of Torrevieja following the appearance of so-called blue dragons, which have been branded ‘the most beatiful killer in the ocean’

The sea slug, also known as Glaucus atlanticus, feeds on the deadly Portuguese man o' war and other venomous seabeasts. Pictured: Guardama beaches which have been closed

The sea slug, also known as Glaucus atlanticus, feeds on the deadly Portuguese man o’ war and other venomous seabeasts. Pictured: Guardama beaches which have been closed

This image shows how the beach would look if it wasn't closed. Pictured: tourists sunbathing on a beach of Guardamar del Segura town in 2018

This image shows how the beach would look if it wasn’t closed. Pictured: tourists sunbathing on a beach of Guardamar del Segura town in 2018

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‘Bathing is prohibited following the appearance on Vivers Beach of two specimens of Glaucus atlanticus, known as the Blue Dragon.’

He added: ‘We remind people that despite its bright and striking colour and it’s small 1.5 inch size, they should stay away from this animal because of its sting.

‘Guardamar del Segura Town Hall has has launched a preventive operation to detect possible specimens carried by ocean currents.

‘Town hall workers are closely following the evolution of the situation and will inform people about the different measures to be taken.

‘If you see one of these creatures don’t touch it, even with gloves on, alert lifeguards and other authorities.

‘If you get stung, wash the area affected with salt water and head to your nearest first aid point or health centre.

‘These creatures are poisonous and their stings can cause nausea, pain and vomiting.

‘For the time being and until further notice, bathing in the sea is prohibited.’

Vivers Beach, a natural stretch of coast south of the Segura River and north of La Babilonia Beach, was said to be full of people yesterday although less people than normal were in the sea defying the bathing ban order and risking heavy fines.

The sea slug, also known as Glaucus atlanticus, feeds on the deadly Portuguese man o' war and other venomous seabeasts

The sea slug, also known as Glaucus atlanticus, feeds on the deadly Portuguese man o’ war and other venomous seabeasts 

The dazzling blue creature absorbs the stinging cells from its food and stores them in concentrated doses, giving it a far more potent sting than its prey. Typical symptoms of the blue dragon's sting include nausea, pain, vomiting and acute allergic contact dermatitis

The dazzling blue creature absorbs the stinging cells from its food and stores them in concentrated doses, giving it a far more potent sting than its prey. Typical symptoms of the blue dragon’s sting include nausea, pain, vomiting and acute allergic contact dermatitis

Guardama beaches re-opened today with a yellow flag

Guardama beaches re-opened today with a yellow flag

Vivers Beach, a natural stretch of coast south of the Segura River and north of La Babilonia Beach, was said to be full of people yesterday although less people than normal were in the sea defying the bathing ban order and risking heavy fines. Pictured: Beach in Guardamar del Segura, Spain

Vivers Beach, a natural stretch of coast south of the Segura River and north of La Babilonia Beach, was said to be full of people yesterday although less people than normal were in the sea defying the bathing ban order and risking heavy fines. Pictured: Beach in Guardamar del Segura, Spain

Lifeguards with loudhailers were expected to remind tourists and locals today about the prohibition according to local reports, although sunseekers will still be allowed to head to beaches even if they don’t take a dip in the sea.

Red flags went up at Santa Barbara beach in La Linea de la Concepcion near Gibraltar on Sunday after police received an emergency call about a blue dragon sighting and six were later found on the shoreline.

It was reopened to bathers the following day, with a yellow warning flag up instead of the red one.

Guardamar Del Segura’s mayor Jose Luis Saez announced around midday today local time beaches in the municipality had reopened but bathers were still being urged to exercise caution.

He said: ‘Yellow flags are now up on the beaches of Guardamar following the closure of the special surveillance operation due to the presence of two blue dragon specimens.

‘Municipal services, police and lifeguards remain alert to developments in the situation.’

Yellow flags mean swimming is allowed but caution is advised and it’s best to stay close to the lifeguard zone.

This is not the first time dangerous sea creatures have caused swimmers to be banned from the water in Costa Blanca.

In 2018, bathers were told to avoid the ocean after the reappearance of Portuguese men o’war.

An 11-year-old boy was rushed to hospital after being stung by one of the jellyfish-like creatures on the few beaches that remained open on some of the most popular parts of the coastline with British holidaymakers.

The red flag was also hoisted at La Marina beach near Elche – where the youngster was hurt – after he was stung.

Lifeguards removed the animal’s tentacles from his arm but he was taken to nearby Elche Hospital after complaining of stomach and neck pain.

He was discharged a few hours later after receiving treatment.

Local reports said nearly 75 miles of Costa Blanca coastline had been declared off limits.

This is a breaking news story, more to follow.