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Josu Álvarez
Madrid
Tuesday, 23 July 2024, 09:45
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Every summer the rising temperatures provoke the arrival of jellyfish to Spain's beaches, especially where the Mediterranean touches land - a popular place for holidaymakers, so it is important to pay attention to their presence if you are planning to spend a few days making the most of the area. This year's new arrival is known as the fried egg jellyfish (Cotylorhiza tuberculata), a species that has spread chiefly around Alicante's coastline. Its curious appearance, very similar to that simple, culinary delight of the same name, has lent it that nickname.
Jellyfish sightings along the Spanish coast are common, although in recent years their presence is greater during the summer months due to climate change. The predominant species vary according to region and season. Along the Cantabrian coasts of Euskadi and the Atlantic Sea running right down to Tarifa, oceanic jellyfish predominate during the first weeks of summer, such as the Portuguese man o' war seen recently along the Costa de la Luz. These are 'false jellyfish' whose sting is very dangerous and from which some bathers from San Sebastian and one from Chiclana have already suffered. In the case of the Mediterranean it is more common to see them during the months of July, August and September.
The new 'fried egg' jellyfish found mainly in the Mar Menor do not pose a risk, according to experts. "It is important to remember that these jellyfish are in their habitat, they have their function in the ecosystem and it is not necessary to bring them ashore on purpose", state the people behind Proyecto Mastral, an initiative that aims to provide weather and climate information for the Alicante area.
Estos días tenemos la llegada de grandes bancos de medusas a nuestras calas, playas y también a la zona del puerto. Las más abundantes son las llamadas "huevo frito" (Cotylorhiza tuberculata), llamada así por su parecido con esa elaboración culinaria. pic.twitter.com/T0KPutF03T
— Proyecto Mastral (@ProyectoMastral) July 15, 2024
The decline of natural predators due to overfishing and the loss of biodiversity have a direct influence on the overpopulation of jellyfish, which are washed ashore by ocean currents. Climatic conditions are another key factor as rising temperatures, drought and lack of rainfall have limited the flow of inland waters into the sea. These cooler waters usually act as a natural barrier to limit the arrival of a large swarm (or bloom) of jellyfish on the coasts. However, the lack of rainfall means that the temperatures of the waters running off the land to the seas remain similar to those of the oceanic waters for a longer period of time, making the formation of the barrier more difficult.
Every year, many bathers suffer jellyfish stings while enjoying a hot summer's day on one of the 8,000 kilometres of beaches in Spain. In most cases contact with a jellyfish only causes minor discomfort in the form of burning or stinging, although you should be careful with some of them because they are extremely dangerous.
For this reason, here we tell you which are the most common species so that you can tell them apart in case you come across any of them during the summer. The list not only includes species commonly seen in the Mediterranean, but also along the rest of the Spanish coast, and the degree of danger that each carries in those tentacles.
The aforementioned jellyfish with the appearance of a fried egg (25-30 cm in diameter) that has taken up residence in the Mediterranean and the Mar Menor belongs to the Cepheidae family. It has eight arm-like tubes covered with small, tentacle-like appendages. It is not particularly dangerous, as its capacity to produce urticaria (skin rash, hives) is low due to the short length of its tentacles. Its effects are mild and do not go beyond minor skin irritation and itching.
The return of the proliferation of this species, which practically disappeared in 2016, is a symptom of the recovery of the ecosystem in the Mar Menor, according to the Naturalists' Association of the South-East (ANSE). This points to a greater transparency in the waters there, which favours both reproduction and a greater presence of this species.
The so-called luminous jellyfish (about 20 cm) has 16 tentacles and its entire body surface is covered with warts. It is characterised by a reddish-pink colour and can grow to more than 20 cm in diameter. In English it is more commonly known as the mauve stinger.
It is plentiful in both the Atlantic Ocean and the Mediterranean Sea and is high risk. It causes irritation and itching of the skin and can even leave an open wound that can become infected, hence its other common name being 'purple people eater'. In addition, the effect of the venom may cause respiratory, cardiovascular and dermatological problems that can be prolonged over time.
The barrel jellyfish (aka dustbin-lid or frilly-mouthed jellyfish, but mostly known as 'aguamala' (bad water) in Spanish) is the largest on this list (90-100 cm). It has eight thick tentacles and is bell-shaped and bluish-white in colour. It is adorned with about 80 violet-coloured lobes. It frequents both Mediterranean and Atlantic coasts and is of medium risk, as it does not cause serious dermatological conditions. However, it can cause irritation not only by direct contact, but also by its mere presence in coastal waters closed to the open sea (as with rock-pools or natural bathing pools), because it releases fragments of its tentacles.
The common jellyfish (up to 25 cm), or moon jellyfish or saucer jellyfish, poses no danger. It is the best known of all the species and is saucer-shaped. It contains numerous short tentacles and you can find them in coastal areas and lagoons such as the Mar Menor, but also in coves, inlets and enclosed bays where inland waters flow to the sea.
The compass jellyfish (up to 30 cm) belongs to the luminescent family (Pelagiidae) of jellyfish, including sea anemones. It is yellowish white in colour and has a distinctive radial pattern of 16 outward-facing, v-shaped points, much like the markings on a compass, although in some specimens the pattern may not stand out.
It has 24 long, thin tentacles that can reach up to 5 metres in length. Its sting is high risk, as it causes itching and burning. Soon after it causes erythematous lesions (circular, bulging, reddened rash shaped like a target with a bullseye that can quickly become infected, even necrotic) and oedema (intense swelling of skin tissue). It is relatively common in the Mediterranean and Atlantic, although they can sometimes swarm.
The famous Portuguese man o' war (30x10 cm) is a 'false jellyfish', as it is a hydrozoan, a siphonophore - that is, it is not a single animal, it is a colonial organism made up of many smaller units called zooids. Some were sighted this month in La Concha Bay in San Sebastian and six were washed up on La Barrosa Beach in Chiclana, leaving several people affected by their stings as it is a very dangerous species due to its potent venom. In addition to burning and lacerating the skin, the pain from the sting can cause neurogenic shock (trouble keeping heart rate, blood pressure and body temperature stable because of damage done to the nervous system), with the consequent danger of drowning before help arrives.
It frequents the Atlantic but is occasionally observed in Mediterranean waters or along the Cantabrian coast. This distinctive colony of polyps is made up of a floating part of purplish, transparent gas in the shape of a sail, which makes it easier for it to move in the wind. It has a multitude of tentacles that can extend up to 20 metres underwater.
The jellyfish known as by-the-wind sailor (also the sea raft, purple sail or little sail), just 1-8 cm wide, is another small, modified hydrozoan with a bluish, oval disc enclosing the float and containing the horny skeleton equipped with a sail. There is no risk with this species although it is easy to spot as it lives on the ocean surface.
The jellyfish aequorea (up to 30 cm), commonly known as the many-ribbed jellyfish, has a flat, transparent shape with numerous black radial canals. There is zero danger with this species and it is usually found in Atlantic waters. In the Mediterranean it appears occasionally, although its numbers are currently increasing in the waters surrounding Catalonia and the Balearic Islands.
The sea wasp (5-6 cm) is a species of cubozoan (one of the box jellyfish - alarm bells should sound here) with a transparent, bluish or whitish colour that makes it difficult to see in the water. It has four long tentacles that can extend up to 10 times the size of the umbrella.
It is a very rare and very dangerous creature in equal parts. Difficult to spot along the coast because it does not inhabit the surface waters, preferring life close to the seabed.
The warty comb jelly or sea walnut is a species of ctenophore (the largest animals to swim with cilia (combs)). It grows up to 10cm, is bulb-shaped with a transparent, lobed body and has no tentacles. Instead there are four rows of ciliated combs that run along the body vertically and glow blue-green when disturbed. It poses no risk.
It is an invasive species due to its reproductive speed (they are hermaphroditic and can lay up to 3000 eggs per day). Not only that, but it is not native to these waters, only to western Atlantic coastal waters. It was introduced into the Black Sea where it contributed to the collapse of numerous fisheries. It has now spread to other parts of Europe and Asia.
Hopefully we can all spend an enjoyable summer on the beaches of Spain without a sting in the tail, but at least we now know which jellyfish to spot - and avoid.
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