This has significance because the fish and invertebrate life that regularly inhabit the shore evolve special strategies to deal with the fluctuating environmental conditions. This means that they are often the easiest of marine creatures to keep in aquaria. With British species, the temperature needs to be kept low, below 19 o C. Briefly, two methods are employed to deal with the bionomical problems. Salinity Shore and estaurine animals that are able to live in lowered salinities are called osmoregulators. These animals are few in number, distinguished on British shores by the Shore Crab, Carcinus maenas.
All marine fish drink water to avoid osmotic loss.
They retain salts, especially sodium and chloride, at the same time. This osmoregularatory function requires high oxygen demands 1 . The dissolved oxygen content in pools, aquaria, and the open sea is likely to fall as the temperature rises. In high temperatures, or after a heavy feed, the increased respiratory function of rock pool fish like the Blennies can be clearly observed. The Common Blenny will leave the water in such circumstances, and a tank containing these fish should have rocks above the surface.