Trends in Economic Zoology Online Test 11th Science

Based on the economic importance, animals can be categorized into four types:

• Animals for food and food products
• Economically beneficial animals
• Animals of aesthetic importance
• Animals for scientific research.

Vermiculture is the process of using earthworms to decompose organic food waste, into a nutrient-rich material capable of supplying necessary nutrients which helps to sustain plant growth.

The aim is to continually increase the number of worms to have a sustainable harvest. The excess worms can either be used to expand a vermicomposting operation or sold to customers. Vermicompost is the primary goal of vermiculture.

Vermicompost on the other hand, is comprised of the castings, bits of bedding and other organic matter. Applications of earthworm in technology of composting and bioremediation of soils and other activities is called Vermitech.

Earthworms play a vital role in maintaining soil fertility; hence these worms are called as “farmer’s friends”. These are also called as “biological indicators of soil fertility”.

The reason is that they support bacteria, fungi, protozoans and a host of other organisms which are essential for sustaining a healthy soil. The disposal of solid wastes (biodegradable and non- biodegradable) remains a serious challenge in most of the countries.

Earthworms are divided into two major groups. The breakdown of organic matter by the activity of the earthworms and its elimination from its body is called vermicast.

Earthworms are divided into two major groups. The first group, the humus formers, dwell on the surface and feed on organic matter. They are generally darker in colour. These worms are used for vermicomposting. The second group, the humus feeders, are burrowing worms that are useful in making the soil porous.

There are different endemic (native) species of earthworms cultured in India for vermicomposting such as Periyonyx excavatus, Lampito mauritii, Octochaetona serrata. Some earthworm species have been introduced from other countries and called as exotic species Eg. Eisenia fetida, Eudrilus eugeniae.

Earthworms release their castings on the surface. One can start harvesting this from the surface on noticing the castings on the surface. It may take several days for the entire biomass to be composted depending on the amount of biomass.

Zoology, there are several specializations that the students can venture into.  There are physiologists, who study the metabolic processes of animals; there are taxonomists who deal with the naming and the classification of animal species; embryologist whose job is to study and focus on the early developmental stages of animal life.

Earthworm enemies include ants, springtails, centipedes, slugs, mites, certain beetle larvae, birds, rats, snakes, mice, toads, and other insects or animals which feed on worms.

Earthworms are subjected to attack by a variety of pests. Most outbreaks are the result of poor bed management. The earthworm has a number of internal parasites including numerous protozoa, some nematodes, and the larvae of certain flies. Larger predators can be excluded from worm beds by proper construction of the bins, and by use of screens or gratings at the bottom and top of the beds.

Marketing of vermicompost can provide a supplementary income.

• Vermicompost is rich in essential plant nutrients.
• It improves soil structure texture, aeration, and water holding capacity and prevents soil erosion
• Vermicompost is a rich in nutrients and an eco-friendly amendment to soil for farming and terrace gardening.
• It enhances seed germination and ensures good plant growth

Being eco-friendly, biodegradable and self-sustaining material; silk has assumed special relevance in present age. Historical evidence reveals that sericulture was practiced in China long back.

Silk is Nature’s gift to mankind and a commercial fibre of animal origin other than wool. Cotton and Jute are plant based commercial origin.

Silk has assumed special relevance in present age. Sericulture is an agro –based industry, the term which denotes commercial production of silk through silkworm rearing.

Historical evidence reveals that sericulture was practiced in China long back and they preserved the secret for more than 3000 years and maintained monopoly in silk trade with the rest of the world.

According to Western historians, mulberry cultivation spread to India about 140BC from China through Tibet. The fabulous silk from China and India were carried to European countries.

The 7000 miles lengthy road, historically called the “Silk road” passing through Baghdad, Tashkent, Damascus and Istanbul was used for silk transport.

Today more than 29 countries in the world are practicing sericulture and producing different kinds of silk. India stands second in silk production next to China.

Production of silk from the silk worm, by rearing practices on a commercial scale is called sericulture. It is an agro-based industry comprising three main components: i) cultivation of food plants for the silkworms, ii) rearing of silkworms, and iii) reeling and spinning of silk. The first two are agricultural and the last one is an industrial component. Only few species of silkworms are used in the sericulture industry.

The adult of Bombyx mori is about 2.5 cm in length and pale creamy white in colour. Due to heavy body and feeble wings, flight is not possible by the female moth.

Just after copulation, female starts egg laying which is completed in1-24 hours. A single female moth lays 400 to 500 eggs depending upon the climatic conditions.

Two types of eggs are generally found namely diapause type and non-diapause type. The diapause type is laid by silkworms inhabiting the temperate regions, whereas silkworms belonging to subtropical regions like India lay non-diapause type of eggs.

The eggs after ten days of incubation hatch into larva called as caterpillar. The newly hatched caterpillar is about 3 mm in length and is pale, yellowish-white in colour.

The newly hatched caterpillar is about 3 mm in length and is pale, yellowish-white in colour. The caterpillars are provided with well-developed mandibulate type of mouth-parts adapted to feed easily on the mulberry leaves.

After 1st, 2nd, 3rd and 4th moultings caterpillars get transformed into 2nd, 3rd, 4th and 5th instars respectively It takes about 21 to 25 days after hatching. The fully grown caterpillar is 7.5 cm in length.

The fully grown caterpillars stop feeding and move towards the corner among the leaves and secretes a sticky fluid through their silk gland. The secreted fluid comes out through spinneret (a narrow pore situated on the hypopharynx) and takes the form of long fine thread of silk which hardens on exposure to air and is wrapped around the body of caterpillar in the forms of a covering called as cocoon.

The length of continuous thread secreted by a caterpillar for the formation of cocoon is about 1000-1200 metres which requires 3 days to complete. The pupal period lasts for 10 to 12 days and the pupae cut through the cocoon and emerge into adult moth.

The first component, is to grow the food plants for the silkworms. Mulberry leaves are widely used as food for silkworm Bombyx mori and the cultivation of mulberry is called as Moriculture.

Presently improved mulberry varieties like Victory1, S36, G2 and G4 which can withstand various agro – climatic and soil conditions are used for planting. The favourable season for cultivating of the mulberry plants is June, July, November and December.

The mulberry crop production technology includes land preparation, preparation of cutting, planting techniques, maintenance of mulberry nursery, disease and pest management and uprooting for raising new mulberry gardens.

The small larvae (caterpillars) hatch between 7-10 days. These larvae are kept in trays inside a rearing house at a temperature of about 20°C – 25°C. These are first fed on chopped mulberry leaves. After 4-5 days fresh leaves are provided. As the larvae grow, they are transferred to fresh leaves on clean trays, when fully grown they spin cocoons. Their maturity is achieved in about 45 days. At this stage the salivary glands (silk glands) starts secreting silk to spin cocoons

The method of obtaining silk thread from the cocoon is known as post cocoon processing. This includes stifling and reeling.

The process of killing the cocoons is called stifling. The process of removing the threads from the killed cocoon is called reeling. For reeling silk the cocoons are gathered about 8 -10 days after spinning had begun.

New silkworm diet produces coloured silk. The Institute of Materials Research and Engineering (IMRE) in Singapore has developed a way to replace the traditional dying process necessary to make coloured silk.

Silk fibres are utilized in preparing silk clothes. Silk fibres are now combined with other natural or synthetic fibres to manufacture clothes like Teri-Silk, Cot-Silk etc. Silk is dyed and printed to prepare ornamented fabrics. They are generally made from Eri-silk or spun silk. Silk is used in industries and for military purposes. It is used in the manufacture of fishing fibres, parachutes, cartridge bags, insulation coils for telephone, wireless receivers, tyres of racing cars, filter fibres, in medical dressings and as suture materials.

The profitable silk industry is threatened by various diseases caused by the virus, fungal, bacterial and protozoan infections but also by insect predators, birds and other higher animals. Ants, crows, kites, rats, feed upon silk worms thereby causing a great loss to silk industry.

Pebrine, is a dangerous disease to in silkworms and the causative organism is Nosema bombycis, a protozoan. This silkworm disease is transmitted through the egg of the mother silkworm and also through ingestion of contaminated food.

Care and management of honey bees on a commercial scale for the production of honey is called Apiculture or Bee Keeping. The word ‘apiculture’ comes from the Latin word ’apis’ meaning bee.

There are five well recognized types of bees in the world. They are Apis dorsata (Rock bee), Apis florea (Little bee), Apis indica (Indian bee), Apis mellifera (European bee) and Apis adamsoni (African bee).

In honey bees, a highly organized division of labour is found. A well-developed honey bee colony consists of the Queen, Drones and Workers. All the three types depend on each other for their existence. There is normally one queen, 10,000 to 30,000 workers and few hundred drones (male bees) in a colony.

Queen bee is a functional female bee present in each hive and feeds on Royal Jelly. Its sole function is to lay eggs throughout its life span. The virgin queen bee mates only once in her life.

During the breeding season in winter, a unique flight takes place by the queen bee followed by several drones. This flight is called “nuptial flight”.

The queen bee produces a hormonal chemical substance called pheromone. The drones in the area are attracted to the pheromone and mating takes place.

In a life span of two to four years, a queen bee lays about 15 lakh eggs. When the queen bee loses its capacity to lay eggs, another worker bee starts feeding on the Royal Jelly and develops into a new queen.

Among the honey bees, workers are sterile females and smallest but yet function as the main spring of the complicated machinery in the colony. Worker bee lives in a chamber called ‘Worker Cell’ and it takes about 21 days to develop from the egg to adult and its lifespan is about six weeks.

Honey bee uses its long-tube like tongue to extract sugary liquid called nectar from the flowers. The nectar is stored in the stomach and the enzyme invertase transforms it into honey.

The drone is the functional male member of the colony which develops from an unfertilized egg. It lives in a chamber called drone cell. Drones totally depend on workers for honey.

The sole duty of the drone is to fertilize the virgin queen hence called “King of the colony”. During swarming (the process of leaving the colony by the queen with a large group of worker bees to form a new colony) the drones follow the queen, copulates and dies after copulation.

The house of honey bee is termed as bee hive or comb. The hive consists of hexagonal cells made up of wax secreted by the abdomen of worker bees arranged in opposite rows on a common base.

The main objective is to get more and more quality honey. There are two methods used by apiculturists. They are indigenous method and the modern method.

In Apis dorsata, the brood cells are of similar in size and shape but in other species, brood cells are of three types viz., queen cell for queens, worker cell for workers and drone cells for drones.

Bees teach us a lesson to work with cooperation. Imagine the hard-work of the bees! A single honey bee travels about double the distance of the circumference of the earth’s globe for preparing 453.5ml of honey.

Bee wax is secreted by the abdomen of the worker bees at the age of two weeks. The wax is masticated and mixed with the secretions of the cephalic glands to convert it into a plastic resinous substance

Honey is the healthier substitute for sugar. The major constituents of honey are: levulose, dextrose, maltose, other sugars, enzymes, pigments, ash and water.

Honey is an aromatic sweet material derived from nectar of plants. It is a natural food, the smell and taste depend upon the pollen taken by the honey bee. It is used as an antiseptic, laxative and as a sedative. It is generally used in Ayurvedic and Unani systems of medicine. It is also used in the preparation of cakes, breads and biscuits.

The resinous chemical substance present in the wax is called propolis which is derived from pollen grains. The pure wax is white in colour and the yellow colour is due to the presence of carotenoid pigments. It is used for making candles, water proofing materials, polishes for floors, furniture, appliances, leather and taps.

The culture of lac insect using techniques for the procurement of lac on large scale is known as Lac culture. Lac is produced by the lac insect Tachardia lacca previously known as Laccifer lacca. It is a minute, resinous crawling scale insect which inserts its probosics into the plant tissues and sucks juice, grows and secretes lac from the hind end of the body as a protective covering for its body.

The insect is a parasite on host plants i.e., Karanagalli (Acacia catechu), Karuvelai (Acacia nilotica) and Kumbadiri (Schleichera oleosa). The quality of lac depends upon the quality of the host plant. The female lac insect is responsible for large scale production of lac, which is larger than the male lac insect.

After copulation, the male insect dies. The female develops very rapidly after fertilization and lays about 200 to 500 eggs

The female lac insect is responsible for large scale production of lac, which is larger than the male lac insect. Eggs hatch into larvae after six weeks.

The mass emergence of larvae from the egg in search of a host plant is called ‘swarming’. After settling on the host, the larvae start feeding continuously and the secretion of lac also starts simultaneously. Gradually the larvae become fully covered by lac.

Hyperparasitism – A condition in which a secondary parasite develops within a previously existing parasite or a hyperparasite is the parasite whose host is also a parasite.

Lac cultivation is a complicated process, so the cultivators should know well about the inoculation, swarming period and harvesting of lac. The process of introducing lac insect on the host plant is called inoculation.

Lac cut from the host plant is called ‘Stick lac’. The lac present on the twig is scraped and collected. After grinding, the unnecessary materials like dusts and fine particles are removed.

The collection of lac from the host plant is known as harvesting. Harvesting may be done before swarming (immature) or after swarming (mature). Immature harvesting produces ‘Ari lac’

The lac present on the twig is scraped and collected. After grinding, the unnecessary materials like dusts and fine particles are removed. The resultant lac is called ‘seed lac’. The seed lac is sun dried and then melted to produce ‘shellac’.

Lac is largely used as a sealing wax and adhesive for optical instruments. It is used in electric industry, as it is a good insulator.

Economic importance of Lac:

• It is used in preparations of shoe and leather polishes and as a protective coating of wood.
• It is used in laminating paper board, photographs, engraved materials and plastic moulded articles.
• Used as a filling material for gold ornaments

Aquaponics is a technique which is a combination of aquaculture (growing fish) and hydroponics (growing plants in non-soil media and nutrient-laden water). Aquaponics may also prevent toxic water runoff. It also maintains ecosystem balance by recycling the waste and excretory products produced by the fish.

In India, aquaponics was started in 2013. Some primary methods of aquaponic gardening that are in use nowadays are as follows: Deep water culture, Media based method, Nutrient Film technique, Aqua vertica.

Deep water culture is otherwise known as raft-based method. Media based method involves growing plants in inert planting media like clay pellets or shales. Nutrient Film technique involves the passage of nutrient rich water through a narrow trough or PVC pipe. Aqua vertica is otherwise known as vertical aquaponics.

Cultivable fishes like tilapia, trout, koi, gold fish, bass etc., are cultured in aquaponics. Common cultivable plants like tomato, pepper, lettuce, cucumber, and rose are co-cultivated in this method.

Aquaculture has been practiced in varying forms for centuries dating to the time of the Phoenicians. India offers a huge potential for aquaculture development.

Fish culture received notable attention in Tamil Nadu in 1911. Aquaculture is a branch of science that deals with the farming of aquatic organisms such as fish, molluscs, crustaceans and aquatic plants.

On the basis of source, aquaculture can be classified into three categories. They are (a) Freshwater aquaculture (b) Brackish water aquaculture (c) Marine water aquaculture.

Culturing of fishes is called fish culture or pisciculture. Inland water bodies include freshwater bodies like rivers, canals, streams, lakes, flood plain wetlands, reservoirs, ponds, tanks and other derelict water bodies and ponds constructed for fresh water aquaculture.

The pH of the freshwater should be around neutral and salinity below 5 ppt (parts per thousand).

Brackish water fishes spend most of its life in river mouths (estuaries) back waters, mangrove swamps and coastal lagoons.

Estuarine fish are more common in Bengal and Kerala. Culturing of animals in the water having salinity range 0.5-30 ppt are called as brackish water culture.

Fishes cultured in brackish water are Milk fish (Chanos Chanos), Sea bass (‘Koduva’), Grey mullet (‘Madavai’), Pearl spots (‘Kari’meen) etc,

Marine Fisheries deal with fishing operations along seacoasts. The Indian subcontinent approximately has a 5600 kms long coastline.

About 80% of India’s marine fish are supplied by the west coast and the remaining 20% by the east coast. The premier varieties are mackerels, sardines, sharks, and catfish.

Marine edible fishes of Tamil Nadu coast include both cartilaginous and bony fishes. Culturing of animals in the water salinity ranges from 30 – 35% is called Mariculture.

Culturing of animals in the salinity ranges from 36 – 40% is called Metahaline culture. Eg, Brine shrimp (Artemia salina).

Artemia is commonly known as the brine shrimp. It is a crustacean and lives in high saline waters because of its high osmoregulatory capacity.

Characteristics of cultivable fishes

The special characteristic features of cultivable fishes are:

• Fishes should have high growth rate in short period for culture.
• They should accept supplementary diet.
• They should be hardy enough to resist some common diseases and infection of parasites.
• Fishes proposed for polyculture should be able to live together without interfering or attacking other fishes.
• They should have high conversion efficiency so that they can effectively utilize the food.

Cultivable fish are of 3 types:

• Indigenous or native fresh water fishes (Major carps, Catla, Labeo, Clarias)
• Salt water fishes acclimatized for fresh water (Chanos, Mullet).
• Exotic fishes or imported from other counties (Common carps)

Among these, major carps have proved to be best suited for culture in India, because the carps

• Feed on zooplanktons and phytoplanktons, decaying weeds, debris and other aquatic plants.
• They can survive in turbid water with slightly higher temperature
• Can tolerate O2 variations in water.
• Can be transported from one place to other easily.
• They are highly nutritive and palatable.

The factors that affect fish culture are temperature, light rain, water, flood, water current, turbidity of water, pH hardness, salinity and dissolved O2. Light and temperature also play an important role in fish breeding.

Induced breeding is also done by hypophysation (removal of pituitary gland). The gonadotropin hormone (FSH and LH) secreted by the pituitary gland influences the maturation of gonads and spawning in fishes.

Most important aquatic crustacean is prawn, which is widely cultured prawn flesh is palatable and rich in glycogen, protein with low fat content.

Estuaries and back waters or saline lake prawn fishery – The area of production of prawns are the back waters seen along the Western coast, Ennur, Pulicat, Chilka lake and Estuaries of Ganga and Brahmaputra rivers.

A number of species of prawn are distributed in water resources such as Penaeus indicus, Penaeus monodon, Metapenaeus dobsoni and Macrobrachium rosenbergii. Catla catla is fish variety.

Macrobrachium rosenbergii is commonly seen in rivers, fields and low-saline estuaries. The prawn collected from ponds, river, and paddy fields are transferred to the tanks which are aerated.

Several factors that determine the success of marine prawn culture includes selection of site, water quality, soil quality and availability of seed.

Pearl is a white, highly shining globular concretion found within the shell of an Oyster. Pearl oysters are sedentary animals.

In India it was cultured for the first time in 1973 at Thoothukudi. Pearl oysters are found along the coast of Kanyakumari and in the Gulf of Kutch

High quality pearls are obtained from pearl oysters of Genus Pinctada that can be cultured in the salinity range of 30 ppt in racks, raft and long line methods.

Freshwater bivalve Lamellidens is also used in artificial pearl culture. Mostly the pearl oysters inhabit the ridges of rocks or dead corals, forming extensive pearl banks. These pearl beds produce best quality of pearls.

Oysters are caught by special type of cages (84 x 54 x 20 cm) by covering a heavy wire frame with two centimeter wire mesh. These cages are suspended at a depth of 6 meters. From July to November, where spats are easily available. These collected oysters are now transferred to rearing cages.

The collected oysters are stocked and reared in special type of cage called as rearing cage. These cages are well protected from enemies of oysters like Octopus, Eel, Devil fishes etc.

The pearls obtained are of variable shapes and sizes. They may be white, or cream red or pink red in colour. The spherical pearls of rainbow colour are rarely found. The best quality of pearl is obtained from marine oysters. Pearl obtained from freshwater bivalves are not as valuable as those obtained from the marine oysters.

Animal husbandry is the practice of breeding and raising livestock cattle like cows, buffaloes, and goats and birds etc. that are useful to human beings.

Parameters such as adequate ventilation, temperature, sufficient light, water and proper housing accommodation should be taken into account to maintain dairy and poultry farms. Animals should be cared and protected from diseases. Records should be maintained after the regular visits by Veterinarian. More over the selection of good breeds with high yielding potential combined and resistance to diseases is very important

Objectives of Animal breeding:

• To improve growth rate
• Enhancing the production of milk, meat. Egg ,
• Increasing the quality of the animal products
• Improved resistance to diseases e. Increased reproductive rate

Breeding between animals of the same breed for 4-6 generations is called inbreeding. Inbreeding increases homozygosity and exposes the harmful recessive genes.

The breeding between unrelated animals is called outbreeding. Individuals produced do not have common ancestors for 4-6 generations. Outbreeding helps to produce new and favourable traits, to produce hybrids with superior qualities and helps to create new breeds. New and favourable genes can be introduced into a population through outbreeding.

Out crossing is the breeding between unrelated animals of the same breed but having no common ancestry. The offspring of such a cross is called outcross. This method is suitable for breeding animals that are below average in productivity.

Cross breeding: Breeding between a superior male of one breed with a superior female of another breed. The cross bred progeny has superior traits (hybrid vigour or heterosis.)

Have you heard about Mule? It was produced by the process of interspecific hybridization between a male donkey and a female horse.

Artificial insemination is a technique in which the semen collected from the male is injected to the reproductive tract of the selected female. Artificial insemination is economical measure where fewer bulls are required and maximum use can be made of the best sire.

Thawing means to melt or become liquid. When the semen collected for artificial insemination is taken to far off places/stored for a long time in frozen condition it should be brought to room temperature slowly before use. This process is called thawing

Dairying is the production and marketing of milk and its products. Dairy operation consists of proper maintenance of cattle, the collection and processing the milk and its by-products. There are 26 well defined breeds of cattle and 6 breeds of buffaloes in India.

To meet the milk demand of the growing population, milk breeds are preferred by farmers in small scale farms. Goats are also used all over India for supplementing deficiencies in milk production.

Some of the breeds of cattle that are good milkers are Jamunapari in Ganga-Jamuna riverine tracts, Beetal in Punjab, Bar–bari in Uttar Pradesh.

Cattle in ill health appear dull, restless and change posture frequently with drop in milk yield. The main diseases of dairy cattle are rinderpest, foot and mouth disease, cow pox, hemorrhagic fever, anthrax.

Milk is produced by dairy animals which is an emulsion of fat and lactose. Milk also contains enzymes which are destroyed during pasteurization.

Milk is a rich source of vitamin A, B2, B1, and deficient in Vitamin C. Due to its high nutrition value, it serves as a complete food for infants.

India is the largest producer of Milk, globally. India has many popular indigenous breeds of cows and buffaloes. Prominent indigenous cow breeds in India – Gir, Red sindhi, Sahiwal, Hallikar, Amritmahal, Khillari, Kangayam, Bargur, Umblachery, Pulikulam, Alambadi, Tharparkar, Haryana, Kankrej, Ongole, Krishna valley and Deoni.

Meat is rich in protein and also contains many minerals like iron, zinc, vitamins and selenium. It also contains vitamins needed for human diet.

The most common and commercially farmed birds are chicken and ducks. Poultry farming is essential for the purpose of meat, eggs and feather production. Commercial poultry farming is also profitable.

There are more than 100 breeds of chicken. The commonly farmed chicken breeds are categorized into five based on the purpose for which it is farmed. They are egg layers, broiler type, dual type, games and ornamental types

Leghorn is the most popular commercial breed in India and originated from Italy. They are small, compact with a single comb and wattles with white, brown or black colour. They mature early and begin to lay eggs at the age of 5 or 6 months. Hence these are preferred in commercial farms. They can also thrive well in dry areas.

Chittagong is the breed chiefly found in West Bengal. They are golden or light-yellow coloured. The beak is long and yellow in colour. Ear lobes and wattles are small and red in colour. They are good egg layers and are delicious

Silkie is a breed of chicken has a typical fluffy plumage, which is said to feel like silk and satin. The breed has numerous additional special characters, such as black skin and bones, blue earlobes, and five toes on each foot, while the majority chickens only have four.

A number of poultry by products like blood-meal, feather meal, poultry by product meal and hatchery by-product meal are used as good sources of nutrients for meat producing animals and poultry. These by-products supply proteins, fats, vitamins and good amount of minerals.

Poultry diseases:

Ranikhet, Coccidiosis, and Fowl pox are some common poultry diseases.

Chickens communicate with more than 24 vocalizations, each with a distinct meaning, including warning their friends about different types of predators or letting their mothers know whether they’re comfortable.

Duck is an aquatic bird and forms only 6% of our country’s poultry population. There are about 20 breeds of ducks. The native one includes Indian Runner and Syhlet meta.

The feathers of poultry birds are used for making pillows and quilts. Droppings of poultry can be used as manure in fields. The droppings are rich in nitrogen, potash and phosphates.

Advantages of duck farming:

They can be reared in small backyards where water is available and needs less care and management as they are very hardy. They can adapt themselves to all types of environmental conditions and are breed for feed efficiency, growth rate and resistance to diseases.