Medical brain notes 33

  Corals - reef builders -  ECONOMIC ZOOLOGY   Most of us know about corals and are not familiar with their biology.  Coral rocks  are actually the skeletal remains, primarily of calcium carbonate secreted by living coral polyps. The coral organisms belong to the phylum : Coelenterata .   All reef building corals live as large colonies. Reef corals are typically shy, nocturnal feeders. During the day, polyps are withdrawn into skeletal cups and the corals appear more or less lifeless. But at night time the whole reef magically comes to life and coral polyps stretch out their tentacles, prob-ing the waters for food. The reef looks like a field of flowers.   Reef forming corals grow only in shallow, tropical seas where the temperature of the water never falls below 20 o  c. Only in warmer waters, the coral polyps can extract calcium from the sea water and deposit it as calcium carbonate in their skeletons. Corals thrive only in crystal clear water. ...

  Earthworm - Vermiculture   The growth of industries, urban cities and the ever increasing human population have led to an increased accumulation of waste materials. Waste materials introduced into the environment are of two types namely non-degradable and degradable wastes. The disposal of these solid wastes remains serious challenge in most of the countries.   Waste biomass from agriculture, domestic, urban and industrial sources remains the main cause of organic pollution in many countries, including India. Degradable or decomposable materials constitute a major percentage of the refuse (more than 60%).   New technologies are now available for recycling some of these solid wastes. These wastes can be utilized in vermitechnology for the production of earthworm casts and earthworm tissue protein.   India produces about 2500 million tonnes of organic wastes annually. If properly managed about 400 million tonnes of plant nutrients can be produced from this huge ...

  Beneficial Insects   Insects affect man's welfare in many ways. Many insects are benefi-cial to man.  Beneficial insects  are divided into two main groups according to the nature of benefit derived from them. They are  Productive  and  Help-ful insects .   I. Productive Insects   These insects produce certain substances which are useful to humans. The important useful insect products are  Honey ,  Silk  and  Lac . A. Honey bee   Honey bees are social insects. They live as colonies. They are active throughout the year. They feed on the pollen and nectar of flowers. In India there are four different varieties of honey bees. Of these, only three species are useful in collecting honey.   1.     Apis dorsata  (Rock bee). This is the largest of the Indian honey bees. It   produces plenty of honey. It builds large open single combs which may often be four feet long on tall forest trees. It is ...

  Prawns, Lobsters and Crabs - ECONOMIC ZOOLOGY   A. Prawns   The prawns are one of the most economically important fishery organism of India. It helps to earn a sizeable amount of foreign exchange. The prawns are the most esteemed food among the marine food organisms. There-fore, they are in great demand both in the local and international markets. Export of 'prawn pulp' to Burma and Malaya from earlier times and 'frozen and canned' prawns to USA and Japan in recent years has made Indian prawns a major foreign-exchange earner. Apart from being a delicacy, prawns are a rich source of protein and vitamins (A and D). They contain considerable quantities of glycogen and free aminoacids in their muscles imparting their flesh a sweet taste. As they contain very little fat, they have become a favourite protein food for the weight conscious persons.   Indian prawns of commercial importance   Penaeus indicus, P. monodon, P. japonicus, Metapenaeus dobsoni, M. monoceros M...