Overall, red king crabs have a high adaptation capacity in changes of salinity level because the crabs retain their vital functions and their feeding activities. A difference is seen, though, in the salinity tolerance between juvenile and adult red king crabs. Juveniles are slightly more tolerant to low salinity because their volume regulation is significantly better. Juveniles are consistently hyposmotic to the seawater because they have lower sodium concentration in their hemolymph. As the juveniles are smaller, their exoskeleton is more rigid. The adult red king crabs are hyperosmotic in high salinity and becomes hyposmotic in lower salinity. The hyperosmoticity is due to the higher sodium and potassium concentrations in the hemolymph compared to the surrounding water they live in.