Archive for the 'Aquatic mammal' Category

Vanishing Species: Indian Otters

Sunday article by Mohan Pai

 
Indian Otters
Mustelids
Photo: courtesy: K. Pichumani
 
Playful creatures, a group of Otters is called ‘romp’, being descriptive of their playful nature.
Otters are semi-aquatic, fish-eating mammals. The otter subfamily Lutrinae forms part of the family Mustelidae, which also includes weasels, polecats, badgers, as well as others. With thirteen species in seven genera, otters have an almost worldwide distribution. They mainly eat aquatic animals, predominantly fish and shellfish, but also other invertebrates, amphibians, birds and small mammals.An otter’s den is called a holt or couch. A male otter is a dog (otter), a female a bitch (otter), and a baby a whelp or pup. The collective nouns for otters are bevy, family, lodge or romp, being descriptive of their often playful nature, or when in water raft.
India is home to three species of otters: the Eurasian otter (Lutra lutra), the smooth-coated otter (Lutra perspicillata) and the small-clawed otter (Amblonyx cinerous). Just 50 years ago, the smooth coated otter, also referred to as the smooth Indian otter, was widespread in the country while both Eurasian and the small clawed otter (earlier called the clawless otter) were absent from central India, but found in broad bands in the Himalayas and the ghats in the south. It is essentially an otter of cold hill and moutain streams and lakes. Today, these elegant creatures are confined only to protected areas and zoos. If there are any unknown pockets outside, they are unlikely to survive.What happened to otters was quite simple. Found in rivers, lakes and other wetlands, they competed with human beings for fish, their main diet, and lost. Pollution poisoned their food and habitat. Lakes and wetlands were drained for agriculture. In fact the trade of otter skins has been going on for hundreds of years in South East Asia. According to a wildlife trade survey done in Thailand, an otter skin can be sold for $90-$100 to leather factories and considered the best leather to make jackets. It is also believed that otter fat was good for rheumatism, and dried otter penis can fetch up to $50 per inch in Mandalay, and in Myitkyina in the Kachin state. A researcher from the Centre for Ecological Sciences, Bangalore, V. Meena, found nomadic tribal herb collectors from Haryana trapping otters in the Palani hills of Tamil Nadu to sell the oil and skin and of course, eat the flesh, while they were at it.
Characteristics
Otters have long, slim bodies and relatively short limbs, with webbed paws. Most have sharp claws on their feet, and all except the sea otter have long muscular tails.They have a very soft, insulated underfur which is protected by their outer layer of long guard hair. This traps a layer of air, and keeps them dry and warm under water.Many otters live in cold waters and have very high metabolic rates to help keep them warm. In summer, in the Himalayas many otters go up the streams and torrents ascending to altitudes of 12,000 ft or more. Their upward movement probably coincides with the upward migration of carp and other fish for purposes of spawning. With the advent of winter they come down to the lower streams.For most otters, fish is the primary staple of their diet. This is often supplemented by frogs, crayfish and crabs. Some otters are expert at opening shellfish, and others will feed on available small mammals or birds. Prey-dependence leaves otters very vulnerable to prey depletion.Otters are very active, chasing prey in the water or searching the beds of rivers, lakes or the seas. Most species live beside water, entering it mainly to hunt or travel, otherwise spending much of their time on land to avoid their fur becoming waterlogged. The sea otter does live in the sea for most of its life.Otters are playful animals and appear to engage in various behaviors for sheer enjoyment. Different species vary in their social structure, with some being largely solitary, while others live in groups – in a few species these groups may be fairly large.

Range map of Otters (IUCN)

Major Threat(s): The aquatic habitats of otters are extremely vulnerable to man-made changes. Canalisation of rivers, removal of bank side vegetation, dam construction, draining of wetlands, aquaculture activities and associated man-made impacts on aquatic systems are all unfavourable to otter populations (Reuther and Hilton-Taylor 2004). In South and South East Asia, the decrease in prey species from wetlands and water ways had reduced the population to an unsustainable threshold leading to local extinctions. The poaching is one of the main cause of its decline from South and South East Asia, and possibly also from the North Asia. (IUCN Red List)
References: Wikipedia, IUCN Red List, S. H. Prater (the book of Indian Animals), Aniruddha Mookerjee in the Hindu.

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Vanishing Species – The Blue Whale

An article by Mohan Pai

 
The Blue Whale
Balaenoptera musculus


Critically endangered Blue Whale is the largest animal to have ever lived, almost as big as Boeing 737 and even larger than the biggest dinosaurs.

 With lengths up to 100 feet (30 m) and weights up to 150 tons (136 metric tons), the blue whale is the largest animal that ever lived on this planet. An average individual is 70 feet (21 m) long and weighs 100 tons (90 metric tons). The female, which is larger than the male, gives birth to a calf that averages 25 feet in length and weighs about 2 tons. The calf drinks about 106 gallons of milk every day. An average adult has almost 2,500 gallons of blood and burns up to 3 million calories a day. Its heart weighs more than a ton and the tongue alone weighs about 2 tons! Linnaeus must have had his tongue in his cheek when he gave this species the Latin name “musculus,” which means “little mouse.”As the common name indicates, the upper parts of the body are mottled blue-gray. The undersides are whitish or light yellow. This whale has a relatively small dorsal fin and black baleen plates. The straight, column-like water spout can reach 20 feet into the air. Speeds of up to 23 miles per hour (20 knots) have been recorded for the blue whale.
 For many, many years ancient sailors had rare encounters with these gigantic ocean mammals and were terrified by their overwhelming size and powerful tails. You can understand a little of the fear and trepidation they might have felt upon seeing these huge, mysterious creatures for the first time. Today we know them to be virtually harmless to humans and that they have quite a bit in common with us – they, too are warm-blooded mammals that must breathe air. They are highly social animals with complex languages and intelligence. Most importantly, they are not monsters at all, but gentle giants we have come to respect, admire and protect.
 
Size comparison against an average human
 Diet
Blue whales diet consists mainly of krill, a tiny shrimp that lives in tremendously large schools in almost every ocean of the world. Krill is probably one of the most plentiful food species (outside of insects) anywhere on earth. It’s got to keep up with the blue whale’s big appetite. A big blue can eat over a thousand krill at one time swallowing them with a tongue that weighs as much as an elephant! Blue whales eat the krill using a special type of filter on their mouths called a baleen. By gulping enormous amounts of sea water containing the live krill the blue whale closes its mouth and flushes the sea water back out through the filter leaving the krill behind for it to swallow. Small fish and plankton are also favorite food items of the whale. It takes about 8,000 lbs/3600kg of fresh seafood a day to keep the blue whale well fed.
 Vocalisation
Probably the most spectacular thing about blue whales that’s bigger than big is the sounds they make. Scientists have measured the low-frequency (deep rumbling) sounds they make when they communicate with each other by using a decibel meter. Some of their vocalisations have been recorded as loud as 188 decibels and can be heard as far as 530 mi/848km away. To give you an idea of just how loud 188 decibels is a commercial jet taking off makes a sound of 120 decibels. That makes whales, by far, the loudest living thing anywhere on earth!
 Range
Found in the Atlantic, Pacific, Arctic and Indian Oceans, with a range that extends from the periphery of drift-ice in polar seas to the tropics . Three main populations persist: one in the southern hemisphere, one in the North Pacific and one in the North Atlantic ).
In India, the Blue Whales have been washed ashore in Karnataka, Maharashtra, Gujarat, Tamil Nadu, Kerala and Andhra Pradesh.
 
Red area indicates the range of the Blue Whale

Life History

Blue whales migrate several thousand miles to wintering grounds and fast for the duration of their stay; the fat on their body is enough to see them through the whole winter. The mating season occurs for 5 months over the winter. A single calf is born after a gestation period of one year. It nurses for 7 months and will reach sexual maturity at 5-15 years of age. Females give birth every 2-3 years.
 Status
The blue whale is currently one of the world’s most endangered whales. It was not hunted until somewhat modern techniques made them more easily attainable.
 Blue Whales were abundant in nearly all the oceans until the beginning of the twentieth century. For over 40 years, they were hunted almost to extinction by whalers until protected by the international community in 1966. A 2002 report estimated there were 5,000 to 12,000 Blue Whales worldwide, located in at least five groups. More recent research into the Pygmy subspecies suggests this may be an underestimate. Before whaling, the largest population was in the Antarctic, numbering approximately 239,000 (range 202,000 to 311,000). There remain only much smaller (around 2,000) concentrations in each of the North-East Pacific, Antarctic, and Indian Ocean groups. There are two more groups in the North Atlantic, and at least two in the Southern Hemisphere.

Blue Whale skeleton, outside the Long Marine Laboratory at the University of California, Santa Cruz

Major Threats

The main threat in the past was direct exploitation, which only became possible in the modern era using deck-mounted harpoon cannons. Blue whale hunting started in the North Atlantic in 1868 and spread to other regions around 1900 after the northeastern Atlantic populations had been severely reduced. The Antarctic and North Atlantic populations were probably depleted to the low hundreds by the time whaling ceased, but are increasing . Blue whales have been protected worldwide since 1966, although they continued to be caught illegally by former USSR fleets until 1972. The last recorded deliberate catches were off Spain in 1978.

 

References: Dept. Of Environmental Conservation, New York State, Wikipedia, IUCN Red List.

 

MY BLOG LIBRARY
For some of my articles visit:
http://mohanpaiblogger.blogspot.com/
http://mohanpaisarticles.blogspot.com/
http://biodiversity-mohanpai.blogspot.com/
For some key chapters from my book “The Western Ghats”, please log on to:
http://westernghats-paimohan.blogspot.com/

For detailed blog (6 Chapters from my book) on Mahadayi/Mandovi River Valley, please log on to
:http://mohan-pai.blogspot.com/

For the book ‘The Elderly’ please log on to:
http://oldagecare-paimohan.blogspot.com/
http://omashram.sulekha.com/blog/posts.htm
You can also access my blogs on Sulekha and WordPress:
http://mohanpai.sulekha.com
https://mohanpai.wordpress.com/
For my book “The Flight of Gods – Hindu Temples & Shrines of Goa” please log on to:
http://flightofgods.sulekha.com/blog/posts.htm
http://flightofgods.blogspot.com/


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