. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. 222 ZOOLOGY state similar to the taproot which has lost water by osmosis) so that the muscles can be drawn through without injury. The lobster also molts a part of the lining of the digestive tract as far as the posterior portion of the stomach. Immediately after molting the lobster is in a helpless condition, and is more or less at the mercy of its enemies until the new shell, which is se- creted by the skin, has grown. This process takes several weeks to complete. Economic Importance. — T
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. 222 ZOOLOGY state similar to the taproot which has lost water by osmosis) so that the muscles can be drawn through without injury. The lobster also molts a part of the lining of the digestive tract as far as the posterior portion of the stomach. Immediately after molting the lobster is in a helpless condition, and is more or less at the mercy of its enemies until the new shell, which is se- creted by the skin, has grown. This process takes several weeks to complete. Economic Importance. — The lobster is highly esteemed as food, and is rapidly disappearing from our coasts as the result of overfishing. Between twenty million and thirty million are yearly taken on the North Atlantic coast. This means a value at present prices of about $15,000,000. Laws are now 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 extinction. Some states now hatch and care for the young for a period of time; the United States Fish Com- mission is also doing much good work, in hope of restocking to some extent the now almost depleted waters. Shrimps. — Several other common crustaceans are near relatives of the crayfish. Among them are the shrimps and prawns, thin- shelled, 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 fishes, they do not appear to be decreasing in numbers. Be- sides this value as a food, they are also used by man, the shrimp fisheries in this country aggregating almost $1,000,000 yearly. The Blue Crab. —Another edible crustacean of consid- erable economic importance is the blue crab. Crabs are found inhabitin
Size: 2069px × 1208px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookpublishernewyorkamericanbookcompany, booksubjectbiology
