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Cyclommatus metallifer
Topic Started: Aug 30 2012, 10:55 AM (4,376 Views)
linnaeus1758
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Cyclommatus metallifer

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Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Family: Lucanidae
Subfamily: Lucaninae
Genus: Cyclommatus
Species : Cyclommatus metallifer

Size: 45 - 90 mm. (including mandibles)
Range: Indonesia.

The males of these beetles can reach 9 centimeters in length, of which about half are in their formidable jaws, equipped with powerful spines, with which engage in fierce battles for supremacy against females. These, in turn, barely exceed 3 centimeters in size.
They are light brown in colour with a metallic bronze. The femora of the legs are, in many individuals, red.
Only found in the wild in the jungles at certain islands of Indonesia (Sulawesi, Sangir, Peleng, Bangkulu, Sula, Bachan, Halmahera and Morotai). In fact, it is considered that the different population of these islands are of different subspecies.
Females lay the eggs on decaying wood.

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Edited by linnaeus1758, Jun 13 2014, 03:35 PM.
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Scalesofanubis
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I'd have almost thought it was a piece of art, or maybe some kind of robot before I thought it was an actual beetle.
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Taipan
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Stag beetle battles: How ungainly jaws bite so hard

By Victoria Gill
Science reporter, BBC News
27 March 2014 Last updated at 00:52

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Researchers have staged stag beetle battles to solve the mystery of how the male beetles bite so hard.

The extreme length of the beetles' jaws should make it difficult for them to produce a forceful bite.

As well as measuring the bite forces that the beetles could produce, the scientists, from Antwerp University, filmed stag beetle fights to assess their biting power.

The findings are reported in the Journal of Experimental Biology.

Stag beetles do not use their impressive jaws to eat, as you might expect, but rather to attract females and to fight and wrestle with other males over territory.

"They seem very ferocious," Jana Goyens, from the University of Antwerp, who led the study, told BBC News.

"But long [jaws] should not be very efficient when it comes to transferring very large bite forces - it would seem from a mechanical point of view that they would not bite forcefully."

This is because the force generated by muscles in the beetle's head has to be transferred down to the end of each jaw, or mandible. So, just like a very long lever, the force has to work over a long distance.

You can experience this rule of mechanics with your own body.

If you hold your arms straight out in front of you and press your hands together, it is difficult to produce a great deal of force. But if you bring your hands in close to your chest, you can push your palms together with much more force.

Beetle battles

Ms Goyens staged and filmed fights between the male beetles to determine the distance between their jaws when they grab an opponent.

She then measured the bite force that the beetles could produce at the end of their jaws, and studied scans of the internal anatomy of their heads.

These measurements revealed first that the male head is a lot wider than the female.

"That makes space for longer input levers," Ms Goyens said. Like the handle of a pair of pliers, there is a long lever inside the beetle's head that is hinged to each of its jaws.

"And that enhances the force," she said.

"Second, their entire head is filled with these muscles to close the jaws.

"The head shape of the males is adapted to make space for these enormous muscles. And of course, the bigger the muscles, the larger the muscle force."

Ms Goyens said this was an example of just how extreme evolutionary changes could be.

"Sexual selection has had a very large impact on their anatomy," said Ms Goyens. "To maintain their jaws as a useful weapon, they had to change their entire head."

http://www.bbc.com/news/science-environment-26747922




Biomechanical determinants of bite force dimorphism in Cyclommatus metallifer stag beetles

Jana Goyens, Joris Dirckx, Manuel Dierick, Luc Van Hoorebeke and Peter Aerts
doi: 10.1242/​jeb.091744 April 1, 2014 J Exp Biol 217, 1065-1071.

Abstract
In the stag beetle family (Lucanidae), males have diverged from females by sexual selection. The males fight each other for mating opportunities with their enlarged mandibles. It is known that owners of larger fighting apparatuses are favoured to win the male–male fights, but it was unclear whether male stag beetles also need to produce high bite forces while grabbing and lifting opponents in fights. We show that male Cyclommatus metallifer stag beetles bite three times as forcefully as females. This is not entirely unexpected given the spectacular nature of the fights, but all the more impressive given the difficulty of achieving this with their long mandibles (long levers). Our results suggest no increase in male intrinsic muscle strength to accomplish this. However, morphological analyses show that the long mandibular output levers in males are compensated by elongated input levers (and thus a wider anterior side of the head). The surplus of male bite force capability is realized by enlargement of the closer muscles of the mandibles, while overall muscle force direction remained optimal. To enable the forceful bites required to ensure male reproductive success, male head size and shape are adapted for long input levers and large muscles. Therefore, the entire head should be regarded as an integral part of male armature.

http://jeb.biologists.org/content/217/7/1065.abstract?sid=d2945517-a7f1-47a9-a02d-e57287d21fa2
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