Responses of the sand dollar Scaphechinus mirabilis to extreme environmental changes

The survival ability of the adult sand dollar Scaphechinus mirabilis (Agassiz) in varying environments was studied. In an experiment on a hard substrate, 88% of the animals survived for 40 days (August–September) during variation of sea water temperature from 21.0 to 16.5°C and variation of salinity from 33.3 to 31.5‰. At 17°C, the salinity tolerance range was 34–24‰. At the same temperature. 100% of the animals remained alive for 14 days within a salinity range from 34 to 18‰; at 16 and 14‰ the ratio of surviving sea urchins was 30 and 20% respectively. Thus, S. mirabilis has considerable adaptive capabilities and is able to survive for a long time under extreme environmental changes.