Page:Travel letters from New Zealand, Australia and Africa (1913).djvu/177

 The largest existing animal, the blue whale, is found in the sea, and it attains the enormous length of eighty-six feet. Although living in the sea, the blue whales are air-breathers. They are able, however, to hold their breath for a considerable time under water. When they come to the surface to renew the air supply in their lungs, they first make a violent expiratory effort from the nostril, and drive a column of spray many feet into the air above them. This phenomenon is called "spouting," and whalers are thus able to locate the animals. The skin of whales is often beset with barnacles, some species of which are found nowhere else but on these mammals. Parasitism is very common in the sea, and sometimes as many as four animals are found dependent on each other Some sea-water animals can only be induced to live in the aquarium when the water is kept as pure as it is in the open sea; on the other hand, several of the crustacea seem to flourish best in stinking and putrescent pools It is a fact generally accepted by learned men, that all animals are originally derived from ancestors that lived in the sea. In the birds and reptiles, as well as in the mammals, many things clearly indicate that their ancestors in remote periods, lived in water, and not on dry land. And when we consult the botanists, and find that they agree that all plants must have had a marine origin also, the case for the sea being the original home of all living organisms may be said to be complete We cannot tell in what form life first appeared upon the earth. Whether the unstable living substance called protoplasm was in the earliest conditions of the earth formed spontaneously by the chance