University of São Paulo: Mother of water, jellyfish and caravel: know the species and what to do in accidents

The high season has led to an increase in the number of accidents involving bathers and jellyfish on Brazilian coasts. The phenomenon has grown on beaches in the southern region of Brazil, according to a study published in the Revista da Sociedade Brasileira de Medicina Tropical . A survey by the Fire Department of the State of Rio Grande do Sul used in the study counted more than 254,000 poisonings in two consecutive summers, throughout the state.

According to Renato Nagata, a marine biologist at the Federal University of Rio Grande (Furg), the increase is due to the peak population of these animals coinciding with the summer period in the region. “In other regions of Brazil, some of these species occur at other times of the year, and that’s why they don’t generate this amount of accidents”, he explains. The researcher, who also carried out research at the Center for Marine Biology (Cebimar) at USP, believes that the large number of records is also due “to the good collection of data carried out by the lifeguards”.

Still, Nagata claims that most species found on beaches are harmless. There are about 2,000 types known to researchers, of which only 70 are venomous. Motivated to publicize the main characteristics of these aquatic animals, the biologist from Furg, in partnership with researchers from USP and the Universidade Estadual Paulista (Unesp), prepared the Guide on water mothers and caravels on the coast of Rio Grande do Sul . The material carries the scientists’ knowledge of marine animals and Nagata’s research focused on southern Brazil. However, the guide presents photos and indicates species size, toxicity and abundance by location in Brazil and neighboring countries.

“We know a lot about terrestrial organisms, some people can differentiate between a sparrow and a lapwing, but Brazilian culture lacks this knowledge about marine animals”, he says. For him, although some species are known to fishermen, riverside communities and surfers, there is still a lack of recognition basis to differentiate them.

olindias sambaquiensis
Max size : 10 cm
Toxicity : Moderate intoxications
Abundance : frequent in summer. The main cause of accidents in the state, it leaves painful red marks on the skin. Complications such as allergies are rare. It has numerous thin orange or lilac tentacles protruding from its edge. Its orange gonads form an “X” in the center of the animal.

Physalia physalis (Portuguese caravel)
Max size : 20 cm (float), 30 m (tentacles)
Toxicity : Poisoning can be serious
Abundance : Rare, but massive strandings can occur. It’s not a jellyfish, but it’s also a cnidarian. It has a bluish-purple balloon-shaped float and very long tentacles. It is more common in the Northeast and Southeast of Brazil, but there are large strandings in the summer on beaches in Rio Grande do Sul. Its lesions cause very characteristic red lines.

Chrysaora lactea
Max size : 20 cm
Toxicity : Mild to moderate intoxications
Abundance : common in early summer in Santa Catarina and Uruguay, but occasionally occurs on the coast of Rio Grande do Sul. One of the main species causing accidents on the Brazilian coast. It can have a different color, pink, purple, milky or with red polygons. It has long, thin tentacles protruding from its edge and leafy extensions protruding from the center of its body.
The publication also reinforces Cebimar’s nearly 20-year tradition of collaborating and creating educational materials. Essential for the correct identification of each species, the photos that illustrate the guide count with the participation of the center. Located in São Sebastião, Cebimar accumulates a series of leaflets and e-books about algae, dangerous animals, plankton, reef fish, among others.

“One of the focuses of our work is jellyfish, as many of them and the caravels – the cnidarians – are stinging for humans; they cause what we popularly call ‘burns’. So we put our specialties together in this material to guide people”, explains Alvaro Migotto, professor at Cebimar, who, like Nagata, reinforces the contribution of professor and dermatologist Vidal Haddad Junior. The doctor helps the group to demonstrate the effects of accidents with marine animals on the human body.

Who is the water mother?
Jellyfish, jellyfish, jellyfish or mother of water refer to a set of marine animals, which can be cnidarians, ctenophores and thaliaceans. With transparent bodies and a gelatinous appearance, these animals are invertebrates and their body is made up of 95% water.

Alvaro Migotto explains that jellyfish, as well as caravels, are oceanic organisms and “occasionally arrive close to the coast, causing these public health events”. The reason is not known, but some researchers believe that the degradation of the oceans may have led to an increase in the incidence of water mothers along the coast. According to the guide, the increase in temperature in the oceans, as a result of climate change, tends to favor the reproduction of these organisms. “Given the extension of our territory, there are distinct ecological characteristics on the beaches, which change the composition and the period of occurrence of the species”, adds Nagata.

Upon reaching the coast, most of these animals run aground on the beach and die from dehydration or heat stroke. “It’s part of their life cycle”, reinforce Migotto and Nagata. But remember that, before that, they try to reproduce and feed. “What causes the burning sensation is actually poisoning when we touch them. This poison is a strategy for capturing small animals”, says Migotto, arguing that it is a natural response.

According to the researchers, another characteristic that is often confused by people is the belief that jellyfish “chase” their prey. They have very grippy tentacles and in them there are tiny capsules that contain powerful toxins capable of paralyzing a small fish or crustacean. “These are the cnidas, which act very similarly to the hypodermic needle. When we get close to the tentacles, there is a chemical and mechanical stimulus, triggering these capsules”, details Migotto. The USP professor says that the tentacles resemble a harpoon, whose tips shoot the poison. “They inject below the dermis, and because they are so small, there are usually several hundred cnida shots at anyone who touches them.”

The professor explains that all jellyfish have poison, but not all of them affect us. In the case of accidents with one of these animals, Migotto advises: “It is necessary to remove the tentacles very carefully, without rubbing, because many times some of these capsules have not yet been fired”. This measure, as well as using salt water to wash the area, can prevent further poisoning.

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