Children love to see it dancing and leaping to the tune of sea waves. It lives in schools but it not a pupil. Its friendly strides keep sea farers in good humor. It swims in water, yet it is not a fish. It is an intelligent mammal, but it is not monkey or dog. A constellation of stars has its name, but it is not bear. It performs thrilling acrobatic feats in oceanarium, yet it is not whale. Which is this sea animal then ???
I had read about dolphins earlier, but could see dolphin in its natural glory only in Andaman Sea waters. Watching such friendly animals so close to our boat, swimming and dancing ‘hide and seek’, almost at touching distance, was a thrilling experience. About a dozen sea animals gave us pleasing company for several minutes. Dolphins, generally have a ‘home range’, which may be a few kilometers around. A school of dolphins on Ross Island-Havlock/Baratang axis gives pleasant surprise to many a sea farer. Groups of dolphins appear on the surf lending happiness and a good respite to persons, tired and rundown due to inclement weather and long sea voyage. Dolphins are one of the fastest among the oceanic animals and is capable of attaining speed over 30 knots.
Almost all species of dolphins have sweet, coy appearance, and friendly nature. It is believed that dolphins seldom harm even drowning person, rather help him to float by lending their buoyancy. They also render help to their injured companions. Bottle nosed dolphins, inhabitant of Atlantic, North Pacific and Red Sea have funny curvature of the mouth, with a ‘built in smile’.
Dolphins generally have polygynous social structure with an adult male holding a harem of adult females and young calves. Some young dolphins also move in all-male herds. With polygyny fairly common, the male-female and male-calf bonds are relavively weak. Dolphins have gestation period of 10-111 months. Other female mammals of the harem or the school help in receiving the newborn calf, coming out with tail first, and bring it to sea surface for first breathing.
Dolphins generally feed on delicious sea food of fish, squid and shrimps. Sometimes excessive depletion of food reserves compels these sea mammals to shift to alternate safer feeding areas with adequate availability of food. While foraging, dolphin school, comprising of several hundred animals, often spreads out to from ‘band’, 30 meters to a few kilometers long having a hundred animals or so. Each school has a ‘home range’ like territory of a wildlife species.
Meek and innocent looking sea animals are fairly good and sharp to spot out their prey from large distances, by ultrasound transmissions. They communicate with their kind, through a range of pulses. This sound, is clicks of 0.25Khz , which may go upto ultrasonic range of 80-100 Khz. It is believed that such high frequency signals are used for echo location and stunning the prey. Dolphins have bulging forehead, housing lens shaped pad of fat thought to help focus sonar beams. Ultrasonic sonar system given accurate information to dolphins about the size, distance and speed of the moving object.
Dolphin generally keeps to deeper areas, away from shoreline. Sometimes due to pressure and direction of onshore winds and currents, alongwith configuration of shoreline, dolphins die and get floated ashore. Cases of mass stranding of live dolphins are also noticed. This may be due to infection of the inner ear by nematode parasite, which upsets balance of echolocation abilities. Sometimes underwater explosion or magnetic disturbances also cause such disorientation causing the sea animal fall prey into unfamiliar or shallow waters Dolphins generally follow the leader, which explains the phenomenon of mass stranding or herd stranding.
Dolphins can perform quite complex acrobatic tasks, and are capable of memorizing and showing complex tricks. They are sometimes innovative, give instant responses in mimicry. Their intelligence is remarkable and considered superior to dog and many primates.
Dolphins ae mammals of family delphinidae. There are 32 species which include killer whale, long fined pilot whale, Bottle nosed dolphin, common dolphins, irrawaddy dolphin and Indo-pacific dolphin. Common dolphins, which is the dancing beauty of Bay waters is upto 2.2 meter long and weigh over 70 Kgs.
Dolphins are graceful mammals who deserve protection and tender care. They give cheer and happiness to all, while at sea or in dolphinarium shows. Their display of acrobatics and tricks are amazing and they serve a key role in the marine ecosystem. Let’s protect this wonderful dancing glory of Andaman sea and Bay waters. Cast away harpoons, give rest to nets. Thank you. Haridas50@gmail.com
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