Jellyfish in Spain: A guide to seasonal encounters and safety tips

Spain’s beautiful beaches attract millions of visitors each year, but along with the sun and sand, there’s another marine phenomenon that captures attention: jellyfish.

These ethereal creatures, known for their graceful movements, can often be found in the waters around Spain. In this article, we will provide you with essential information about when to expect jellyfish, how to deal with stings, typical species, and the efforts being made to monitor and control jellyfish populations.

When to expect jellyfish

Jellyfish sightings in Spain tend to be more frequent during the summer months, from June to September. The warm waters of the Mediterranean Sea and the Atlantic Ocean create favourable conditions for jellyfish proliferation. However, it’s important to note that the presence and intensity of jellyfish can vary from year to year and from region to region.

What to do if you’re stung

If you happen to encounter a jellyfish while swimming or enjoying the beach, it’s crucial to know how to respond to a potential sting. The first step is to avoid touching the jellyfish, as even dead ones can still release venom. If you are stung, rinse the affected area with seawater and remove any tentacles using tweezers or a glove-protected hand.

Avoid rubbing the area or using freshwater, as it may worsen the sting. Applying vinegar or a baking soda paste can help neutralise the venom. If there is a lifeguard (socorrista) on the beach, they should be able to help. However, seeking medical attention is recommended if the symptoms persist or if the sting covers a large area.

Types of jellyfish 

Spain’s coastal waters, particularly in summer, are home to a variety of jellyfish species, some more striking—and stinging—than others. Among the most common types of jellyfish in Spain are the Compass Jellyfish

(Chrysaora hysoscella), easily identified by its brownish bell with V-shaped markings, and the bioluminescent Mauve Stinger (Pelagia noctiluca), whose delicate pink hue belies its painful sting.

Another frequent, yet harmless, species in Spanish waters is the Common Jellyfish

(Aurelia aurita). Recognizable by its translucent, bluish-white, plate-shaped bell, it can grow up to 25 cm in diameter. Its most distinctive feature is the set of four horseshoe-shaped, violet reproductive organs visible through its bell. Unlike more venomous species, the Common Jellyfish has short, numerous tentacles, making its sting almost negligible to humans. It thrives in coastal waters, lagoons, and brackish environments, with populations found in places like the Mar Menor.

The Fried Egg Jellyfish

(Cotylorhiza tuberculata), with its distinctive yellow-and-white dome, is a curious sight, while the imposing Rough Rhizostoma, or aguamala, stands out with its large, violet-tinged bell. Found in both the Mediterranean and the Atlantic, these jellyfish are a natural part of Spain’s marine ecosystem.

The Rhizostoma pulmo, also known as the White Jellyfish or Sea Lung

, is one of the largest jellyfish found in Spanish waters, with a bell diameter reaching up to 90–100 cm. Its translucent, bluish-white umbrella is fringed with around 80 violet-colored lobes, while its thick, fused oral arms form a distinctive crown-like structure. Unlike other jellyfish, it lacks marginal tentacles, making its sting less severe. While usually seen alone, it can sometimes appear in large swarms. Interestingly, it is thought to have some active swimming ability, allowing it to seek out nutrient-rich waters.

Another notable presence in Spanish waters is the Portuguese Man o’ War

(Physalia physalis), known locally as the Carabela Portuguesa. Although not a true jellyfish but a siphonophore, this species is infamous for its long, venomous tentacles, which can deliver extremely painful and potentially dangerous stings.

While most stings cause only mild irritation, some—like those from the Mauve Stinger—can be more severe, making awareness and caution essential for beachgoers.

Efforts to monitor and control jellyfish populations

In an effort to improve safety and raise awareness, various initiatives have been implemented in Spain. One notable tool is the MedusApp mobile application, which provides real-time information on jellyfish presence and beach conditions. Users can access data on recent sightings, safety recommendations, and even receive push notifications when jellyfish are reported in their area.

Another app is InfoMedusa from the governmental organisation Aula del Mar Mediterráneo. This app informs about jellyfish on the Malaga coast and requires participation of civilians who can add places where they have seen jellyfish. Furthermore the app is also available in English and French.

Additionally, innovative technologies utilising artificial intelligence (AI) are being developed to aid in the early detection and control of jellyfish blooms. AI algorithms can analyse environmental factors such as sea temperature, currents, and satellite data to predict the likelihood of jellyfish presence. These early warning systems enable beach authorities to take preventive measures and inform the public promptly.

Jellyfish in Spain and climate change

The changing climate is reshaping Spain’s marine ecosystem, with jellyfish playing a key role in this transformation. Warmer sea temperatures and shifting ocean currents are leading to earlier jellyfish blooms, wider distribution, and increased beach strandings. Species like the Portuguese man o’ war, once mostly seen at the end of summer, are now appearing as early as June. With fewer natural predators and favourable conditions, jellyfish populations are thriving, contributing to more frequent encounters and stings along the Spanish coast. Scientists warn that as the Mediterranean has warmed by 1.5°C in the past 40 years, these trends will likely intensify. As tropical species move in and established species expand their range, jellyfish are set to become an even more prominent feature of Spain’s coastal waters.

Also read: AI deployed for jellyfish and “nata” detection on the Costa del Sol