A Civic Biology Part 22

"In their method of learning, although monkeys do not reach the human stage of a rich life of ideas, yet they carry the animal method of learning, by the selection of impulses and a.s.sociation of them with different sense-impressions, to a point beyond that reached by any other of the lower animals. In this, too, they resemble man; for he differs from the lower animals not only in the possession of a new sort of intelligence, but also in the tremendous extension of that sort which he has in common with them. A fish learns slowly a few simple habits. Man learns quickly an infinitude of habits that may be highly complex. Dogs and cats learn more than the fish, while monkeys learn more than they. In the number of things he learns, the complex habits he can form, the variety of lines along which he can learn them, and in their permanence when once formed, the monkey justifies his inclusion with man in a separate mental genus."

Evolution of Man.--Undoubtedly there once lived upon the earth races of men who were much lower in their mental organization than the present inhabitants. If we follow the early history of man upon the earth, we find that at first he must have been little better than one of the lower animals. He was a nomad, wandering from place to place, feeding upon whatever living things he could kill with his hands. Gradually he must have learned to use weapons, and thus kill his prey, first using rough stone implements for this purpose. As man became more civilized, implements of bronze and of iron were used. About this time the subjugation and domestication of animals began to take place. Man then began to cultivate the fields, and to have a fixed place of abode other than a cave. The beginnings of civilization were long ago, but even to-day the earth is not entirely civilized.

The Races of Man.--At the present time there exist upon the earth five races or varieties of man, each very different from the other in instincts, social customs, and, to an extent, in structure. These are the Ethiopian or negro type, originating in Africa; the Malay or brown race, from the islands of the Pacific; the American Indian; the Mongolian or yellow race, including the natives of China, j.a.pan, and the Eskimos; and finally, the highest type of all, the Caucasians, represented by the civilized white inhabitants of Europe and America.

REFERENCE BOOKS

ELEMENTARY

Hunter, _Laboratory Problems in Civic Biology_, American Book Company.

Bulletin of U. S. Department of Agriculture, _Division of Biological Survey_, Nos. 1, 6, 13, 17.

Davison, _Practical Zoology_. American Book Company.

Ditmars, _The Reptiles of New York_. Guide Leaflet 20. Amer.

Mus. of Nat. History.

Sharpe, _A Laboratory Manual in Biology_, pp. 140-150, American Book Company.

Walker, _Our Birds and Their Nestlings_. American Book Company.

Walter, H. E. and H. A., _Wild Birds in City Parks_.

Published by authors.

ADVANCED

Apgar, _Birds of the United States_. American Book Company.

Beebe, _The Bird_. Henry Holt and Company.

Ditmars, _The Reptile Book_. Doubleday, Page and Company.

Hegner, _Zoology_. The Macmillan Company.

Hornaday, _American Natural History_.

Jordan and Evermann, _Food and Game Fishes_. Doubleday, Page and Company.

Parker and Haswell, _Textbook of Zoology_. The Macmillan Company.

_Riverside Natural History._ Houghton, Mifflin and Company.

Weed and Dearborn, _Relation of Birds to Man_. Lippincott.

XV. THE ECONOMIC IMPORTANCE OF ANIMALS

_Problems.--I. To determine the uses of animals._ _(a) Indirectly as food._ _(b) Directly as food._ _(c) As domesticated animals._ _(d) For clothing._ _(e) Other direct economic uses._ _(f) Destruction of harmful plants and animals._ _--II. To determine the harm done by animals._ _(a) Animals destructive to those used for food._ _(b) Animals harmful to crops and gardens._ _(c) Animals harmful to fruit and forest trees._ _(d) Animals destructive to stored food or clothing._ _(e) Animals indirectly or directly responsible for disease._

LABORATORY SUGGESTIONS

Inasmuch as this work is planned for the winter months the laboratory side must be largely museum and reference work.

It is to be expected that the teacher will wish to refer to much of this work at the time work is done on a given group.

But it is pedagogically desirable that the work as planned should be _varied_. Interest is thus held. Outlines prepared by the teacher to be filled in by the student are desirable because they lead the pupil to individual selection of what seems to _him_ as important material. Opportunity should be given for laboratory exercises based on original sources.

The pupils should be made to use reports of the U. S.

Department of Agriculture, the Biological Survey, various States Reports, and others.

Special home laboratory reports may be well made at this time, for example: determination at a local fish market of the fish that are cheap and fresh at a given time. Have the students give reasons for this. Study conditions in the meat market in a similar manner. Other local food conditions may also be studied first hand.

USES OF ANIMALS

Indirect Use as Food.--Just as plants form the food of animals, so some animals are food for others. Man may make use of such food directly or indirectly. Many mollusks, as the barnacle and mussel, are eaten by fishes.

Other fish live upon tiny organisms, water fleas and other small crustaceans. These in turn feed upon still smaller animals, and we may go back and back until finally we come to the Protozoa and one-celled water plants as an ultimate source of food.

Direct Use as Food. Lower Forms.--The forms of life lower than the Crustacea are of little use directly as food, although the Chinese are very fond of one of the Echinoderms, a holothurian.

[Ill.u.s.tration: North American lobster. This specimen, preserved at the U.

S. Fish Commission at Woods Hole, was of unusual size and weighed over twenty pounds.]

Crustacea as Food.--Crustaceans, however, are of considerable value for food, the lobster fisheries in particular being of importance. The lobster is highly esteemed as food, and is rapidly disappearing from our coasts as the result of overfishing. Between twenty and thirty million are yearly taken on the North Atlantic coast. This means a value at present prices of about $15,000,000. Laws have been enacted in New York and other states against overfishing. Egg-carrying lobsters must be returned to the water; all smaller than six to nine inches in length (the law varies in different states) must be put back; other restrictions are placed upon the taking of the animals, in hope of saving the race from extinction. Some states now hatch and care for the young for a period of time; the United States Bureau of Fisheries is also doing much good work, in the hope of restocking to some extent the now almost depleted waters.

Several other common crustaceans are near relatives of the crayfish. Among them are the shrimp and prawn, thin-sh.e.l.led, active crustaceans common along our eastern coast. In spite of the fact that they form a large part of the food supply of many marine animals, especially fish, they do not appear to be decreasing in numbers. They are also used as food by man, the shrimp fisheries in this country aggregating over $1,000,000 yearly.

[Ill.u.s.tration: The edible blue crab. (From a photograph loaned by the American Museum of Natural History.)]

Another edible crustacean of considerable economic importance is the blue crab. Crabs are found inhabiting muddy bottoms; in such localities they are caught in great numbers in nets or traps baited with decaying meat. They are, indeed, among our most valuable sea scavengers, although they are carnivorous hunters as well. The young crabs differ considerably in form from the adult. They undergo a complete _metamorphosis_ (change of form).

Immediately after molting or shedding of the outer sh.e.l.l in order to grow larger, crabs are greatly desired by man as an article of food. They are then known as "shedders," or soft-sh.e.l.led crabs.

[Ill.u.s.tration: The oyster.]

Mollusks as Food.--Oysters are never found in muddy localities, for in such places they would be quickly smothered by the sediment in the water. They are found in nature clinging to stones or on sh.e.l.ls or other objects which project a little above the bottom. Here food is abundant and oxygen is obtained from the water surrounding them. Hence oyster raisers throw oyster sh.e.l.ls into the water and the young oysters attach themselves.

In some parts of Europe and this country where oysters are raised artificially, stakes or brush are sunk in shallow water so that the young oyster, which is at first free-swimming, may escape the danger of smothering on the bottom. After the oysters are a year or two old, they are taken up and put down in deeper water as seed oysters. At the age of three and four years they are ready for the market.

The oyster industry is one of the most profitable of our fisheries. Nearly $15,000,000 a year has been derived during the last decade from such sources. Hundreds of boats and thousands of men are engaged in dredging for oysters. Three of the most important of our oyster grounds are Long Island Sound, Narragansett Bay, and Chesapeake Bay.

[Ill.u.s.tration: This diagram shows how cases of intestinal disease (typhoid and diarrhoea) have been traced to oysters from a locality where they were "fattened" in water contaminated with sewage. (Loaned by American Museum of Natural History.)]

Sometimes oysters are artificially "fattened" by placing them on beds near the mouths of fresh-water streams. Too often these streams are the bearers of much sewage, and the oyster, which lives on microscopic organisms, takes in a number of bacteria with other food. Thus a person might become infected with the typhoid bacillus by eating raw oysters. State and city supervision of the oyster industry makes this possibility very much less than it was a few years ago, as careful bacteriological a.n.a.lysis of the surrounding water is constantly made by competent experts.

Clams.--Other bivalve mollusks used for food are clams and scallops. Two species of the former are known to New Yorkers, one as the "round," another as the "long" or "soft-sh.e.l.led" clams. The former (_Venus mercenaria_) was called by the Indians "quahog," and is still so called in the Eastern states. The blue area of its sh.e.l.l was used by the Indians to make wampum, or money. The quahog is now extensively used as food. The "long" clam (_Mya arenaria_) is considered better eating by the inhabitants of Ma.s.sachusetts and Rhode Island. This clam was highly prized as food by the Indians. The clam industries of the eastern coast aggregate nearly $1,000,000 a year.

The dredging for scallops, another molluscan delicacy, forms an important industry along certain parts of the eastern coast.

[Ill.u.s.tration: Salmon leaping a fall on their way to their sp.a.w.ning beds.

(Photographed by Dr. John A. Sampson.)]

Fish as Food.--Fish are used as food the world over. From very early times the herring were pursued by the Nors.e.m.e.n. Fresh-water fish, such as whitefish, perch, pickerel, pike, and the various members of the trout family, are esteemed food and, especially in the Great Lake region, form important fisheries. But by far the most important food fishes are those which are taken in salt water. Here we have two types of fisheries, those where the fish comes up a river to sp.a.w.n, as the salmon, sturgeon, or shad, and those in which fishes are taken on their feeding grounds in the open ocean. Herring are the world's most important catch, though not in this country. Here the salmon of the western coast is taken to the value of over $13,000,000 a year. Cod fishing also forms an important industry; over 7000 men being employed and over $2,000,000 of codfish being taken each year in this country.

[Ill.u.s.tration: Globe Fisheries.]

Hundreds of other species of fish are used as food, the fish that is nearest at hand being often the cheapest and best. Why, for example, is the flounder so cheap in the New York markets? In what waters are the cod and herring fisheries, sardine, oyster, sponge, pearl oyster? (See chart on page 201.)

Amphibia and Reptiles as Food.--Frogs' legs are esteemed a delicacy.

Certain reptiles are used as food by people of other nationalities, the Iguana, a Mexican lizard, being an example. Many of the sea-water turtles are of large size, the leatherback and the green turtle often weighing six hundred to seven hundred pounds each. The flesh of the green turtle and especially of the diamond-back terrapin, an animal found in the salt marshes along our southeastern coast, is highly esteemed as food.

Unfortunately for the preservation of the species, these animals are usually taken during the breeding season when they go to sandy beaches to lay their eggs.

Birds as Food.--Birds, both wild and domesticated, form part of our food supply. Unfortunately our wild game birds are disappearing so fast that we should not consider them as a source of food. Our domestic fowls, turkey, ducks, etc., form an important food supply and poultry farms give lucrative employment to many people. Eggs of domesticated birds are of great importance as food, and egg alb.u.min is used for other purposes,--clarifying sugars, coating photographic papers, etc.