Sea cucumbers (Holothuroidea) are truly bizarre creatures that seem to have stepped out of a visionary tale by Howard Phillips Lovecraft. These animals, also called sea cucumbers because of their shape, which resembles that of the vegetable, belong to the class of echinoderms — invertebrates characterised by a skeleton made up of spiny calcareous plates, like the starfish and the sea urchin.

What sea cucumbers are

These strange animals, belonging to the class Holothuroidea (Holothuroidea), are recognisable by their distinctive elongated body and move by crawling along the seabed, where they feed on the organic particles in the sediment. Sea cucumbers are found in all the world's seas, with a preference for temperate and tropical ones.

Why sea cucumbers are under threat

Sea cucumbers have a high economic value: they are fished for food in the Mediterranean, in the waters of the Far East, in the Indian Ocean and in the Pacific. In some countries, sea cucumbers are considered a delicacy — particularly in the East. In China, their price ranges between 10 and 600 dollars per kilogram, while certain especially prized species can cost up to three thousand dollars per kilogram.

Not only sea cucumbers at risk — human health too

The excessive harvesting of sea cucumbers is putting their survival at risk. There are 377 known species of these animals; sixteen are considered at risk of extinction by the Red List of the Iucn. The indiscriminate consumption of these animals also puts our food security at risk: sea cucumbers are filter-feeding organisms, like mussels, and can absorb viruses, bacteria, algal biotoxins and heavy metals — they must therefore be caught in unpolluted sea areas.

Uncontrolled fishing of sea cucumbers

According to Elvira Tarsitano, an environmental biologist, the main health and hygiene issues are linked to unauthorised activities aimed at processing sea cucumbers for food. Even in Italian waters, indiscriminate harvesting of sea cucumbers can be observed, animals that find themselves — against their will — at the centre of a growing trade. A few days ago, along the coastline of the Porto Cesareo marine protected area, in Lecce, the carabinieri seized over 150 kilograms of sea cucumbers; the maximum daily catch permitted to a single diver is five kilograms.

Sea cucumbers could disappear from the Mediterranean

The increase in sea cucumber commercialisation can represent serious damage to marine ecosystems and a risk to the survival of sea cucumber populations in the Mediterranean.

The important role of sea cucumbers

Sea cucumbers perform important ecosystem functions: they play a fundamental role in recycling nutrients that can, in turn, feed algae and corals, and they may have an active role in defending coral reefs against ocean acidification. These strange animals are true scavengers of the sea, contributing to preserving the delicate balance of marine ecosystems and marine biodiversity.