Animal with the World's Largest Weapon

Fiddler Crab of Bengkulu Indonesia

If we compare the size of the body  and  its weapon from an animal, such as comparing between the rooster body with its spurs, rhino or deer with its horns or elephant with its tusks, it can be seen that the size of the weapons they have relatively much smaller than their body size. But for fiddler crab, the size of its claw is much larger than its body size. So we can state that this animal if compared to its body size has the largest weapon size of all animals in the world.

It is a Popeye's right hand but without spinach

The Fiddler crabs those are presented here i found in an intertidal mangrove forests around Pulau Baai Port of Bengkulu  in the city of Bengkulu Indonesia. Male of fiddler crabs has a single enlarged claw, while female has two small feeding claws. Fiddler crab feeds by scraping the surface sediment up in its small claws, transferring it to the mouth where the complex mouth parts sift out the organic matter. Because males has only one small, feeding claw, it feeds at half the rate of the female. It therefore has to spend about double the time feeding than female do.

Fiddler crabs are named because of the extreme difference in the size of the claws of the male, with the larger claw resembling a fiddle. Other theory says that the name is coming from the feeding of the males, where the movement of the small claw from the ground to its mouth resembles the motion of a someone moving a bow across a fiddle (the large claw).

Beautiful color of Fiddler Crab

A fiddler crab, sometimes known as a calling crab. The large second claw of the male fiddler crab is known as a secondary sexual characteristic and is used to attract a mate during the breeding season as well as to protect territories. The male crab will stand by the entrance to the burrow waving the larger claw in an effort to attract a female.
Waving to attract females

There are approximately 100 species of semi-terrestrial marine crabs which make up the genus Uca.As members of the family Ocypodidae, fiddler crabs are most closely related to the ghost crabs of the genus Ocypode. This entire group is composed of small crabs – the largest being slightly over two inches across.
Like all crabs, fiddler crabs shed their shells as they grow. If they have lost legs or claws during their present growth cycle a new one will be present when they molt. If the large fiddle claw is lost, males will develop one on the opposite side after their next molt. Newly molted crabs are very vulnerable because of their soft shells. They are reclusive and hide until the new shell hardens.

community of fiddler crab

Around our intertidal mangrove forest around Bengkulu City (near port of Bengkulu - Pulau Baai port) there are few place where this fiddler crab can be found. But even in a small place, they gathered in a huge numbers, i can found maybe hundreds of it in a small place. 

Males and females live intermixed and each individual has its own burrow and a small area of surface sediment around it. The burrow is extremely important. It is a refuge during high tide, and during low tide it is a source of water for keeping the gills wet, it is an escape from predators, it is the site of mating and incubation. The space around the burrow is used for feeding and courting.

The intertidal mangrove forest near Pulau Baai Port of Bengkulu where i found the habitat of fiddler crab

An interesting fact about this animal is, that prostitution not only happen to human, but also to animal. A report from CBSNEWS state that  a research in Australia had found that fiddler crab trade favor for sex !. Wow. Researchers from The Australian National University in Canberra found that male fiddler crabs will happily defend a female neighbor against intruders - partly because the females will dole out sex in return.

The study by Richard Milner, Professor Michael Jennions and team leader Dr Patricia Backwell of the Research School of Biology at ANU looked at how female fiddler crabs “ without the large claw that the males are armed with “ go about protecting their territories. The results of the study are published in Biology Letters.

The researchers found that even though the female crabs are physically no match for attacking males they do have something that can work to their favor: offering sexual favors to neighboring males in exchange for protection. These sexual offerings lead to neighborhood coalitions, where a male crab will protect female neighbors from other homeless males seeking a new territory.

Well, it shocked me to know that there is such trade in animal world. To know this fiddler crab better you can see this video of fiddler crab around intertidal mangrove forest of Bengkulu city Indonesia.

copyright 2011 Nurul Iman Supardi
Bengkulu - Indonesia

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