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Category Archives: Water World

About marine life

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The story still goes on off the South Australian coast near Port Lincoln.

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The Shark

shark

In the silent abyss of our oceans it moves with the deadliness of a striking submarine. The Shark’s reign spreads across vast oceans reaching down up to a depth of 10000 feet. Undeniably it is an enigmatic creature of nature’s vast water worlds and understandably it evokes reactions of fear and horror. None of us could have actually seen a shark in reality but when we stand on the safety of our shores we wonder whether there’s one lurking around. The Shark is familiar to all of us invoking images of ferocious attacks as depicted in movies, books, pictures and dailies. It’s commonly seen as an instinctive killing machine, yet it has an intelligence equal to higher mammals on our terrain. Like every predator it moves around in silent cruelty. And like every predator it’s linked to nature’s grand designs of bio-balances and counter balances.Yet this hunting creature is itself the victim of human hunters. Today the Shark is an endangered species, sought after for its fins which are   much desired delicacies  in many Asian countries. Recipes, when ordered, are status symbols on the table. The fin soup and dishes are also  laced with myths and dubious ideas on a sharks medicinal and curative properties.

There are world wide efforts to protect and preserve the shark.

To know the shark is to admire and preserve it as our planet’s natural heritage, so rich and so beautiful. Let’s not lose the Sharks existence only to watch it hanging from some museum.

In the meantime, from a marine biologist’s point of view this fish is still a puzzle. A mystery of myriad forces waiting to be unraveled by the biological laws and insights of science.

Read on.

Contrary to belief that a Shark is a mindless  killing machine, it has intelligence similar to that of higher territorial mammals . They are said to have a sense of curiosity, problem solving skills and they engage in playful activities.

Movement:

They swim at an average speed of 8 kms/hr ( 5 mph) and when attacking they can reach a speed of 18 lms/hr ( 12 mph).

Body:

Sharks have a highly streamlined body and a cartilaginous skeleton. The skeleton of a shark is different from other fish which are bony. The shark’s skeleton is made of flexible dense tissue that is considered as bone.

SIZE:

Dwarf Lantern Shark: 17 cms ( 7 inches) in length. Deep sea species

Whale Shark: Considered the largest. 12 meters ( 30 feet)

Bull Shark: Best known shark that lives in both fresh water and sea water

Sharks live as deep as 7000 ft. ( 2000 meters). Some live even deeper at 3000 meters ( 10000 ft.)

Diet: Plankton, squid, small fish and mammals. Some like the tiger shark eat almost everything. However most sharks have specific diets that they search for.

Teeth: Shark have powerful cutter teeth which can be replaced every 8-10 days or in several months. A shark can lose 30000 teeth in their lifetime.

Smell: They have a keen sense of smell. Some sharks can detect one part in millions of blood in sea water.

Hearing: Sharks have a sharp sense of hearing and hear their prey many miles away. They also have an electrical sensitivity to detect prey even when they are hiding. Sometimes sharks confuse these electrical fields with those of metal boats and attack the boats, confusing them with prey. Ocean currents and magnetic fields of the earth are used by sharks to sense their way in navigation

Shark Babies:

Shark pups are born in three ways.

1.   Oviparity – Where eggs are laid

2. Viviparity – Young are born alive and functional like mammals

3.  Ovoviviparity – Where eggs hatch inside the mother’s body and are nourished with yolk and body fluids.

Life Span: Life span varies from species to species. The average life span of most sharks is 20-30 years.

Spiny Dogfish: 100 years

Whale Shark: Over 100 years

Sharks are considered as solitary predators but some are highly social.  Many meet together for breeding. Their hunting grounds can range up to thousands of miles where they can cover entire sea basins.

Sharks and Humans:

Sharks are common sea food in many places around the world.

Japan and Australia: Used to make fish and chips, deep fried, crumbed, fried or grilled.

India: Small baby sharks called SORA in Tamil Nadu are fried in oil and spices. Even the bones are considered a delicasy.

Greenland: Sharks are made in HAKARL or fermented shark. it is regarded as a national dish.

Sharks are also killed for their fins out of which soup is made. Fishermen cut the fins and throw the live shark back into the sea. The immobile creature is attacked by predators or dies out of suffocation. This practice is rare but shark fins are a major trade in black markets with fins priced at $ 220/lb. Killing of sharks is illegal and many governments are enforcing laws to protect sharks. the UN has acknowledged the need for shark fishery management. In Asia, there is a demand for fin soup and it’s a status symbol. This finning is leading to shark extinction.

Sharks are not suitable for domestic acqariums. They are too expensive and difficult to maintain.

stop shark finning