Animals

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A Moth Find a New Home
Suicidal Birds
A leopard and A cheetah
The Spectacular Hornbill
The Antelope with an extraordinary nose
Masquerading Males
Tiny But Powerful
Electric Fishes
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Hairless Cat
Passionate Parrot
Calling Out To Mother
Hot Wheels
Discs On Their Wings
Two-humped Camels
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Silken Chambers
Earth Pig
Swordsman of the Sea
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Electrifying Meal
Bizarre Turtle
Grey Whales
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Llamas
A Different Sort of a Parrot
The Tailless Cat
The Ancestor Of The Rhino
Acquisitive Wood Rats
The Butterflyfish
The Amazing Jumper
The Largest Deer
The Devil’s Coach-Horse
The Porcupine With A Prehensile Tail
The Irritating Fencing
The Acrobatic Otter
The Busy Termite Colony
Superb Mimics
The Canary
Snow Monkey
Jumping Spiders
Glass Lizard
Beetle Rhino
The World’s Smallest Bear
Hygienic Ants
Flat as a Pancake
The Carpet Shark
The Centipede Walk

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Illuminate thyself!

By Rani Iyer

Some of the tiniest creatures in the ocean have amazing powers! Consider the luminescent bacteria. Luminous bacteria are gram-negative and occur in two genera, Vibro and Photobacterium. They move around using flagella. In appearance and physiology, they are close to enteric bacteria that occur in the intestine of man and other mammals. The luminescent bacteria occur in symbiotic relationship with organisms that live in deep sea. Cuttle fish, clams, squid, herring, shrimps, and deep-sea anglerfish have organs in their body in which the luminous bacteria live! Flash light fish possess an organ called light organ, in which the bacteria are closely packed and appears to glow in the dark.

Anomalops, a tropical surface water fish, has a luminescent organ beneath the eye!
The bacteria have the luciferace gene, that is also found in fireflies. Luminescent bacteria are rather rare in land, but scary instances of bacterial growth are reported. A Canadian man who wanted to eat a late night snack of crabs was scared out of his wits when they had a blue-green glow in the dark! Some people living in the seaside report the occurrence of 'glowing wounds'! In this case, the luminescent bacteria infected the wound. Passengers on cruise ships, often report an eerie glow from seawater-flushed lavatories! The bacteria can also grow on dead, dying and decaying fish in the ocean.
Why do bacteria produce light? Scientists are not yet sure. But one of the theories is that when a fish accommodates a glowing bacteria, it gets light and the bacteria gets more oxygen than by living in the sea floor. This helps the fish to spot food easily in the forest floor. Such mutual help in a relationship is called 'symbiosis'. The blue-green light produced by marine organisms has evolved due to two reasons. First, blue-green light (wavelength around 470 nm) transmits furthest in water. Second, most organisms are sensitive only to blue light. They lack the visual pigments, which can absorb longer (yellow, red) or shorter (indigo, ultraviolet) wavelengths.
Even among deep-sea fish, there are exceptions to the rule. In the Loose jaws family (Malacosteid), the fish produce only red light. These are not visible to other organisms. The light produced by species of Malacosteus, Aristostomias, and Pachystomias is nearly infrared. Aristostomias has more than one light organ, a red one to spot the prey, and a blue-green one to communicate with others!
Luminescent bacteria occur in oceans of all regions: the Indian, the Atlantic and the Pacific Oceans, of the Black, Mediterranean and other seas, from tropical to polar latitudes and from the surface layers to the depth of several thousand meters.
Next time you visit the seashore, take some time to observe the cuttle bones, clams and other objects that wash to the shore. You might make a new discovery!

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Last updated on :11/24/2003

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User's Comments

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Steve: what is the name of the clam that glows in the dark?? and is it possible to order glow in the dark clam shells online or from anywhere else??

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