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Aug 24 2014

World’s Smallest Shark

lantern-shark

The lantern shark is one of the known species of shark found in the mesopelagic twilight zone of the deep ocean. This area of the ocean continues to fascinate marine researchers and wild life lovers, as it is a veritable cache of discovery.

The lantern shark remains something of an enigma for researchers, as little is known about it, but with new technology being developed and the increased sophistication of underwater cameras carried by remotely operated vehicles capable of descending into depths that have hitherto been inaccessible, and submarines that descend to depths of 7,000ft or more.

Knowledge of these fascinating creatures and the exciting possibility of even more members of the species being discovered is on the increase.

GLOWING DENIZEN OF THE DEEP

The lantern shark is a species of dogfish shark belonging to the family Etmopteridae. The name derives from their ability glow, called bioluminescence.

There are 36 described species, and they are generally small, less than 35 inches long, and they can be found in the deeps worldwide.

Broadbanded_lanternshark_head

World’s Smallest Shark – Lantern Shark

The biggest lantern shark is the great lantern shark, with a maximum recorded length of 75cm.

One of the most distinguishing features of the lantern shark in general is that it possesses light-producing photophores (a light emitting organ found as spots on various marine animals) which are found mainly on its underbelly.

The photophores however are not limited to the underbellies only. There are photophores on the 2 spines in front of the dorsal fins, and there are photophores also on their sexual organs, by which they recognize potential mates and hunting partners.

By a process called counter illumination they are able to glow in a way that to the upturned eye of a predator below them, they become invisible, and by the same token, they are invisible to their prey, until it is too late.

The really special thing about the lantern shark’s bioluminescence is that it is controlled mainly by hormones, unlike bony fish with the same mechanism which utilize brain chemical signals, making it one of a kind among bioluminescent animals.

The lantern shark also has a unique optical apparatus. Previously sharks generally have been thought to have a weak eyesight, and to depend largely on their sense of smell which is very keen (sharks can detect a drop of blood in an Olympic-size swimming pool).

Studies have shown that lantern sharks have a higher density of light-sensitive cells known as rods in their eyes than non-bioluminescent sharks do, which might give these sharks better temporal resolution, which essentially means that they are able to detect changes in the light patterns emitted by one another, and so recognize one another with ease.

They also have the ability to adjust their eye-illumination in such a manner that they can camouflage themselves from sunlight coming from above.

The smallest member of the family, possibly the smallest shark in the world, bar the discovery of any other, is the dwarf lantern shark. It is so small that it can fit into the palm of a man’s hand.

Lantern sharks feed on krill and crustaceans, and thankfully are of no commercial value. They are however at risk of being taken as by catch by deep-sea trawlers.

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Map of where Lantern Shark’s can be found.

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worlds smallest sharkrare-shark-species-deep