The formation of barren grounds due to grazing of sea urchins significantly reduces the biodiversity of an area where they predominate. Although sea urchins are important for ecosystem survival, they can become dangerous in large numbers. In the Mediterranean, two species are responsible for the formation and maintenance of barren grounds: the purple sea urchin Paracentrotus lividus and the black sea urchin Arbacia lixula. They are traditionally used in the diet of many Asian countries, and more recently some European ones. Sea urchin stocks are significantly reduced in these parts of the world, and the main reason is overexploitation. In Croatia, ie in the Adriatic Sea, there is also a significant catch of sea urchins and the biggest problem lies in the poor implementation of legal regulations for the protection of these animals. Sea urchins are very widespread and are found in oceans around the world. Although they are not currently in imminent danger of extinction, due to the already mentioned problem of overexploitation, there is a real possibility that they will become endangered in the future.