Sea urchin injuries

These belong to the bottom-living marine animals from the echinoderms (Echinodermata) strain. There are about 950 species of sea urchins. Their bodies are almost completely enclosed by a skeleton of limestone slabs and carry movable spines. Sea urchins are found in all the world's oceans, but especially on the coasts of Europe, Asia, Central America, Australia and the Pacific islands. The limestone plates of the skeleton are pierced and equipped with suction feet (ambulatory sacral feet). These are used to hold on to the prey, to move around, but also for breathing and sensory perception.

The echinoderms prefer to live on sandy or rocky ground. They often hide in small cavities or between stones, so that bathers easily overlook them and step on them.

In general, most sea urchins cause injuries only through their spines. The spines easily penetrate the skin, especially when stepping on it, break off and remain stuck in the skin because of the barbs. They often crumble when trying to remove them. Some species of sea urchins have toxins inside the sting, which can cause burning and itching at the entry points. In very rare cases, systemic toxin reactions (urticaria, headaches, vomiting, diarrhoea) are possible.

The spines that have penetrated the skin, e.g. in the sole of the foot or at other contact points, must be removed individually. Especially deep-seated spines can only be removed microinvasively. Remaining spine residues cause local infections in the skin, as well as persistent foreign body granulomas, which may have to be surgically removed. This is especially the case if they have penetrated joints (danger of stiffening).

Contact with the short spines of leather sea urchins (Asthenosoma species) hardly leads to visible injuries, but is extremely painful, whereby the pain subsides after 30 minutes.

Injuries caused by the grasping forceps of poisonous tongs of sea urchins (Toxopneustes species) are also extremely painful, but the pain subsides after 30 minutes. In individual cases, symptoms of poisoning may occur.

Contact with the spines of the acanthus starfish (Acanthaster planci), which can be up to 6 cm long, leads to extremely painful injuries. Remains of the spines can be visualised radiologically and must be removed surgically.

After prior disinfection of the skin, it is recommended to remove all sting remains that have penetrated the skin (often in laborious detail work) with pointed tweezers. Deeply penetrated spine tips may have to be removed surgically.

It is highly recommended to wear bathing shoes in sea urchin-rich waters.

1. Stalk C (2015) Sea urchins. In: Traveler's dermatoses. E.v.Stebut Publisher Springer Verlag Berlin-Heidelberg S. 240-242