Towards a scientific-based farming of sea urchins: First steps in the cultivation of Diadema setosum, Diadema savignyi and Mesocentrotus nudus

FISHING OR BREEDING. This question arose relatively recently, but in the last decade, mankind will have to lean more towards the second. Sea reserves of useful species are exhausted. One possible solution to this problem is marine farming. We proposed to investigate the larval development of three sea urchin species: Diadema setosum (Leske, 1778), D. savignyi (Audouin, 1829) (South China Sea), and Mesocentrotus nudus (A. Agassiz, 1864) (Japan Sea). The larvae of Diadema setosum and D. savignyi were very similar, and some differences could only be observed at the late pluteus stage. These sea urchins were developed through the modified pluteus, which only had two pairs of larval arms. The arms were very long - in D. setosum above 2 mm, and in D. savignyi about 5.5 mm. Larval development took about 45 days in D. setosum and 47–50 days in D. savignyi. In contrast, Mesocentrotus nudus (A. Agassiz, 1864) was developed through the pluteus larvae, which had some differences from the pluteus of the genus Strongylocentrotus. Their dimensions did not reach one millimetre. The larval development of Mesocentrotus nudus lasted about 30 days. Analysis of material and time costs has led to the conclusion that Mesocentrotus nudus is the most convenient for obtaining seed material. However, this species cannot be used for the tropical zone. The results of D. savignyi and D. setosum can be used to increase the number of cultivated species.