Dolphins are aquatic mammals; belonging to Order Cetacea. Cetus means a whale or a huge fish. There are around 90 living species in Cetacea divided into two groups.
- First group comprises toothed animals such as dolphins, killer whales; porpoise; sperm whale; beaked whale, narwhal.
- The second group comprises the whales which have filter feeder system. This group comprises blue whale and some other animals.
Thus, dolphins are toothed marine mammals. They have curved mouth that gives them a permanent smile. They vary in size from 5ft to 30ft. The food of dolphins is fish and squid. Dolphins use echolocation (the built in Sonar in dolphins) to locate their prey. At the same time, they also sometimes follow fishing boats, other whales, and birds to find their prey. Since they are marine Mammals; they are warm blooded animals.
Dolphins are considered to be highly social mammals which communicate with squeaks, whistles and clicks. They are also very playful and communicative.
Dolphin Facts
- The smallest dolphin is Maui dolphin, which is around 5 feet long. The largest dolphin is Orca, which can be around 30 ft long.
- Dolphins swim alongside ships, which is basically a way to have fun. This is called bow-riding. The waves created by boats and ships propels them forward and they keep twisting and turning in water. When dolphins swim along and surf in the waves created by the back of boats and ships; it is called wake riding. Dolphins often leap in air when doing bow riding and wake riding.
- Dophins are semihemispheric sleepers; half of their brains go to sleep at a time so that they can keep breathing.
What are marine and freshwater dolphins?
There are around 36 species of Dolphins and most of them are marine, found near coasts and brackish water in every ocean on earth. However, some species of dolphins are freshwater dolphins found in different rivers on earth. The key examples are South Asian river dolphin (this includes Ganges River Dolphin and Indus River Dolphin); Amazon river dolphin (also known as boto), Araguaian river dolphin; Bolivian river dolphin. One more example is Baiji (or Chinese river dolphin), which has possibly become extinct in recent years.
Which dolphins are found in India?
The dolphins found in Indian subcontinent are South Asian river dolphins. Their zoological name is Platanista gangetica. They are freshwater dolphins divided into two subspecies.
- First is Ganges River Dolphin (Platanista gangetica gangetica): This is found in Ganges and Brahamputra rivers and their tributaries in India, Nepal and Bangladesh. It is endangered and around 3500 individuals are alive as of now.
- Second is Indus river dolphin (Platanista gangetica minor). It is found mainly in Indus river in Pakistan and some parts of Beas river in India also. It is also endangered and around 1500 individuals are alive currently.
Apart from that, Satpada of Chilika lake is the home of Irrawaddy dolphins in India. It is located in the state of Odisha.
What are key facts about Ganges River Dolphin?
The scientific name of Ganges River Dolphin is Platanista gangetica gangetica. Their size is between 2 to 2.5 meters. The weight of an adult dolphin is between 70 to 90Kg. Their breeding season extends from January to June. They have been listed as endangered by the International Union for the Conservation of Nature. Their food is several species of fishes, invertebrates etc.
What steps have been taken by Government of India to protect Dolphins?
- The Ganges River dolphins were included in the Schedule-I of Wildlife (Protection), Act 1972 to check their hunting and give them conservation facilities.
- In 1991, the Vikramshila Ganges Dolphin Sanctuary was established in Bhagalpur of Bihar.
- The UPA government prepared a Conservation Action Plan for the Ganges River Dolphin 2010-2020. The plan identified the main threats to these dolphins including – creation of various dams and bridges, irrigation canals and depletion of prey-base due to pollution.
- On 5th October, 2009, Ganges River Dolphin was declared National Aquatic Animal. To commemorate this, October 5 is celebrated as National Ganga River Dolphin Day.
- In his Independence Day Speech this year, Prime Minister Narendra Modi announced the government’s plan to launch a Project Dolphin on the lines of Project Tiger. Project Tiger is considered to be a successful programme helping the Tigers to thrive and survive. The initiative got in-principle approval in December, 2019 at the first meeting of the National Ganga Council (NGC), headed by the Prime Minister.
Why is it important to save dolphins?
There was a time when Gangetic dolphins were plenty in not only Ganga and Brahmaputra but also most of their tributaries. However, construction of dams and barrages, and increasing pollution has led to a decline in the population of aquatic animals in the rivers in general and of dolphins in particular. The Aquatic life is an indicator of the health of river ecosystems. As the Gangetic dolphin is at the top of the food chain, protecting the species and its habitat will ensure conservation of aquatic lives of the river.