The Octopus Worm: Evolution’s Mystery
Worms that give birth to their own grandchildren, animals that have no digestive, muscular, nervous, glandular or excretory organs—such paradoxical creatures are the “dicyemid mosozoans”, tiny worms that live inside octopuses. These little worms are among the most curious living things in nature. It is quite uncertain whether they are a step upward in evolution from the single-celled protozoans or, like some other worms, a degenerate form of many-celled animals. It might be maintained that they represent a distinct branch of the animal kingdom.
The body of a dicyemid consists of a single cell, almost half an inch long, in the form of a hollow tube, surrounded by a layer of small cells. The immediate offspring are formed and, in some cases, live their entire lives and reproduce in turn, inside one of these “skin” cells. The grandchildren break through the body of the grandparent at any place they choose, apparently without causing any wound, and live for a short time as free-swimming animals until they find an octopus whose kidneys they can enter. Then the whole life cycle starts over again.
Apparently the infestation in no way injures the octopus and the worms are of no practical importance in the world. Each kind of octopus or squid in coastal areas has its own particular species of these parasites of which about 35 kinds are known.
The worm’s body contains no organs, tissues or glands in the usual sense of the word.
Before being born the larvae attain their full complement of body cells, are able to swim about, and have within them the germ cells that will give rise to the next generation. Birth is very simple. The larvae just push out, or are squeezed out, through the sides or ends of their parent at almost any point. The parent continues to develop and bear more larvae in the same manner. The number developing at any one time in the cell may range from one or two to 100 or more.
These larvae remain in the octopus as fully developed worms. But at certain times the germ cells develop into much smaller individuals, called infusorigens, hard to distinguish from large protozoa. These never leave the birth cell inside the parent, but produce germ cells of their own which develop into free-swimming creatures known as infusoriforms. These break away from the grandparent worm and from the octopus and become free-swimming animals. They are microscopic, less than a 300th of an inch long. They live from three days to a week. Here may be the borderline between single-celled and multi-celled animals—or perhaps the greatest degeneration in animal life.
The Monster Bear of Kamchatka
A gigantic black bear, probably the largest of flesh-eating animals, lives in the dense, hardly explored pine forests of southern Kamchatka. This creature still is unknown to science. So far as known it never has been seen by a white man. There is, however, considerable evidence for its existence presented in a report made several years ago by Dr. Sten Bergman of the State Museum of Natural History at Stockholm, who spent two years on the Kamchatka peninsula.
Photographs have been taken of this animal’s footprints in the snow. It leaves a track 15 inches long and ten inches wide. Dr. Bergman was shown a pelt of the giant bear. It was the largest bearskin he ever had seen, deep black in color, and covered with short hair in striking contrast to the long hair of other Kamchatkan bears. He also saw a gigantic bear skull, the teeth of which indicate that it belonged to a young individual.