Marine Mammals
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..... l J.J .{.'.1. I 0. ~ [ . ; j': "I'; ';'''l3rHiII " ~ I -:. • • . • 1 Do to cf r ece i pt ........... ... Accesaion No .. ..................... ... ... Claos No. _·.. •• .. •••••• .. ••• .. • .. •• .. •• ..... ,H Marine Mammals P. G. JACOB Central Marine Fisheries Research [nstitute, Cochin - [8 ThE) large scale mortality of about The animals belonging to th e sub 147 pilot whales, probably of the species order Pinnipedia of the order Carnivora Globicephala melaena, which occurred are exclusively marine. They live mainly in the South east coast of India between on fish, molluscs and crustaceans. Manapad and Kulasekharapatnam fishing Walrus (o dobenidae), Seals (Phocidae ) villages in Tamil Nadu d uring January of and Sea lions (Otaridae) are the import this year attracted international atten ant m3rine mammalian carnivores. They tion. According to press reports their live in the Arctic, North Atlantic and the Pacific coasts respectively. Polar size ranged from 220 to 575 cms and they bears are also, to a lesser degree, weighed from 0 . 3 to 2 tons. Even though marine. They are confined to the Arctic experts have pointed out many reasons region, mainly on or near floating ice. like the attack of Killer Whales, suicide Fur-seals belonging to the division committed to balance the population, Otaridae are the most important, econo pollutants present in the seawater; dyna mically. Fur-seals were common in Falk mitting the coral reefs for making land, Kergurin and Prince Edwards cement and starvation due to lack of islands. But they were exploited by proper foed, their deaths remain still a indescriminate slaughter for their valu mystery. In this context, it will be inter able hide. Now they exist on the coasts esting to know more about the mammals of South Africa. Furse'\lls are also found which inhabit the oceans and especially ;n the Pribrilof, Kommander and Kuril their commercial s ignificance to which Islands in the sea of Okhotsk. The in we have hardly paid attention. descrimiqate killing of these animals on Most of the important aquatic mam breeding grounds reduced 5 million mals belong to the orders Carnivora, seasl in 1800 to about llakh in 19 10. This Cetacea and Sirenia. The ancestors of massacre was stopped in 191 1 by the all the present d ay aquatic mammals International Fur seal treaty by U.S.S.R., were land living creatures . They have U.S,A, and Japan. Under this treaty gradually adopted to aquatic life and killing was regulated. This paid back have undergone great changes in body and in the next 30 years the population form and other physiological characters. has increased many times. June, [973 2l Skins of 3 year old male seals are and other marine vegetation. They are taken in June-July months. Hides are supposed to have evolved from the pri stripped from the body and consist of mitive Ungulate mammalians from which pelt and subdermal fat. Pelts are washed stock the present day,! Elephants have and steeped in sea water till the adher also evolved. Halicore (Dugong) lives ing fat hardens. The hardened fat in the Indian Ocean especially in the (blubber) is removed and then the pelts Gulf of Mannar and Palk Bay and in the are cured and salted. Then they are Australian s eas. Manatus (Manatee ) transferred to fur companies. Here lives in the rivers of South America and pelts are graded according to quality. Africa. Sea cows are very much limited They are stretched in frames, heated up in number and at present they are n ot and coarse hair is removed with a blunt commercially exploited. Rhytina (Hy knife. Then they are treated with seal d r odamalis) or " St e ller's Sea Cow" oil and tanned. Further finishing touches which lived in the Berring Strait b e make them soft. It takes about 90 days came extinct by about 176 by ruthless for processing one pelt. Sea lions are human slaughter for its flesh aud fat. also hunted for hide and oil in Cali Order Cetacea includes commercially fornia, Northern Berring sea, Newzea the most important aquatic mammals. land and Australia. There are 20 species Whales and dolphins are all members of Hair seals or Phocidae all over the of Ihis order. Their large scale capture world. Main fishery for Hair seals is in is known as 'Whaling' or 'Whale fish Newfoundland. Harp seal (Phoca green ery '. They are highly modified for landia) is another important species aquatic life by a streamlined body and commercially. Several other species fin-like fore limbs and tail. The hind are important livilihood for people living limbs are absent. The hairy covering around the Arctic region. Pelts of Hair of the skin is reduced to few b ristles seals yield high quality leather which is near the mouth. They have a thick layer used in the manufacture of suit cases of fat (blubber) beneath their skin which and Handbags . Blubber oil is used as a prevents the loss of heat and reduces lubricant. their specific gravity. Their nasal aper The Walruses (Odobenidae) are tures lie far back on the top of the head confined to the Arctic and Pacific icey as a single or double blowhole. Net shores and on floating ice. They under works of blood-vessels (retia mirabilia) take migrations on floating ice . They lie in various parts of the body for are also hunted f?r hide, oil and ivory storing oxygen to be used while under from their tusks. The Alaskan Walrus water. is now protected and except for food for The blue whale (Balaenoptera mus Eskimos, is prohibited from killing. cules) is easily the biggest creature the Marine mammals belonging to the world has ever seen. The Brachiosaurus, orde r Sirenia are heavy bodi9d animals biggest of all the dinosaurs probably with a flat tail. Their fore limbs are weighed 50 tons, but a fat 35 metre blue modified as paddles. They are popu whale may weigh upto 160 tons-bigger larly known as 'Sea-cows' or 'Mermaids'. than three Brachiosauruses, or 20 African They live in estuaries, bays and lagoons bull elephants. Only in the last 300 years and do not go to the open ocean. They have naturalists discovered that the are herbivorous, feeding art sea wee ds whale is not a fish but a mammal. Once 22 Seafood Export Journal a land creature which probably took to derable work has been done on the the water in search of food, it still has anatomy of sound production and hear the structure of 5 fingers burried in its ing of whales. These studies may be flippers, and deep in the flesh of its useful in future for the manipulation of body are two useless bones, the rem both whales and fish stocks. nants of what were once hind legs. Whale's most remarkable adaptation In the thousands of centuries since is the feeding apparatus of the baleen -I it left dry land, the whale has adapted whales, which include the blues and • itself superbly to life in water. Unlike finbacks (Figs. 3 & 4). The status of the fishes it still must surface regularly baleen whales in marine food chain is to breath fresh air, but it can stay under very interesting considering their con water for as long as an hour at a time. sumption of comparatively minute foods. It breathes through the blowhole on top The baleen's tiny throat is just big of its head, letting out the air in a great enough to swallow its main diet of small gust which condenses into a spout. To crustaceans. It swims through a colony protect its eyes from salt water, it has a of shrimp or prawns with its mouth set of glands which secrete an oily sub open, then closes its jaw, raises its stance so that a whale is constantly shed- tongue and expels the water from its . ding great greasy tears. To protect its mouth through a vast soup strainer, the hearing. it has lost its external ear, leav baleen. Baleen is a thick fringe with ing only a small opening which closes numerous horny plates (baleen plates) up tight when it plunges to the great hanging from the palate in rows like the depths of the oceans. We do not know leaves of a book. It allows the water to much about the family life of the whales flow out but will not let the small crusta and dolphins. But judging from the ceans to escape. When the water has size of foetuses found in hunted whales, been expelled the baleen whale glups biologists believe that the mating season the food left behind. is mainly June and July. In courting, big male humpback whale (Fig, 5) spla Compared to the baleen whales the shes and rolls on the surface of the ocean toothed whales like the sFerm whale, to attract the female's attention striking (Fig. 1) eat very simply. They dive far love taps with its flippers that can be into the ocean depths and devour giant heard for miles. To feed the young the squids. Unlike the baleen whale, the mother whale rolls over on her side and sperm whale has a large gullet big special muscles pump milk down the enough to swallow whole, a 3 metre baby's throat - a "baby" that may be shark (or a man name'd Jonah). When 15 metres long. there is a shortage of food supply in For more than 2000 years it has been winter months, both the baleen and known that porpoises and whales make toothed whales live off their blubber, the sounds that m3n can hear.