many get their food from the water; moreover some are such that if they be shut off altogether from the water they cannot possibly live, as for instance, the so called seaturtle, the crocodile, the hippopotamus, the seal, and some of the smaller creatures, such as the fresh water tortoise and the frog: now all these animals choke if they do not from time to time breathe; they breed and rear their young on dry land, or near the land, but they pass their lives in water.