Limule

, Or it, limule (of Latin limulus ) is a marine Euarthropode. Regarded as an alive Fossil , its group practically seems not to have evolved/moved since more 500 million years. The limule is sometimes called “crab of the Moluques” or “crab horseshoe” or “crab with blue blood”, although it is not a Crustacé but a close cousin of the Araignée S and scorpion S. It belongs to the Ecdysozoaires, Panarthropodes, Euarthropodes, Chélicériformes. The limule can measure up to 50 centimetres and live up to 30 years.

Main features

True witness of our “evolution”, it was threatened of extinction following his use by the man like Engrais under pretext of be responsible for an excessive consumption for Mollusques. It was in process of extinction until one discovers, in the years 1960, single properties of sound Sang from now on very studied (see further). The limule since is fished, then slackened after blood sample and marking (to avoid a second blood sample to him).

The limule lives at the not very deep water bottom (5 to 10 meters) and nourishes small marine animals like fish or Crustacé S which it crushes with the base of its forefeet, its mouth being deprived of Dents. Its reproduction is done at the beginning of summer, the female coming with ground once the year, with the full moon. It digs a not very deep hole (20 centimetres approximately) and deposits there its a few thousands of eggs which hatch at the end of one month.

Regarded with the Vietnam as crab of in love one, because the male strongly sticks to the female, it should be consumed both with the loved being.

Particular properties of its blood

The Hémolymphe (equivalent of blood at the Euarthropodes) of the limule is of blue color because of presence of Hémocyanine instead of Hémoglobine.

But most interesting is probably that its cells (the Amebocyte S) react in the presence of Endotoxine S bacterial (compounds having an effect Pyrogène dangerous when they are injected at the man) by producing a protein which transforms it into gel. This freezing makes it possible the limule to block the bacterial infections (the limule does not have an immune system).

This characteristic makes that since the years 1970 one uses the hemolymph of the limule to produce a reagent, called Lysat of Amebocyte de Limule (LAL) which one uses in the pharmaceutical field to test the absence of endotoxines in the drugs, the products of Dialyze and the medico-surgical material.

Vision

A biological characteristic makes that its four primitive eyes detect only the objects moving. Its vision was the subject of multiple research. Each ommatidium leads to only one nervous fiber. Moreover, the nerves are of big size and their access is relatively easy. This anatomical characteristic made it possible to the scientists to analyze the nervous impulses according to the light. Visual phenomena as the side Inhibition could thus be observed. Other experiments made it possible to show that the male limules use the light and the perception of the forms to find partners of day like night. The side eye of the limule offers an image of which the resolution borders 40x25 pixels. It is strongly disturbed but sufficient for the animal.

Taxonomy and biogeography

The family of the Limulidae is represented today by four Espèce S:

Limulus polyphemus (along the east coast of the North America and the Central America)
Tachypleus gigas (Japan)
Tachypleus tridentatus (Filipino)
Carcinoscorpius rotundicauda (Indonesia and Southeast Asia)

The four species are similar in terms of ecology, morphology and Sérologie.

Anecdotes

The limule inspired Hans Ruedi Giger for the creature of the saga Alien when it is in state Face Hugger .

In volume 9 of the adventures of Adele Blanc-Sec (Tardi, 2007), heroin discovers in the Seine, " un" limule (Adele uses the masculine here).

The limule is also a Sous-marin with caterpillar used in the Années 1980 to install underwater cables, in particular cables of exchanges of electricity between the France and the England.

The limules resemble much the Triops which are also alive fossils dating of more than 200 million years, but much smaller and alive out of fresh water.

External bonds

Horseshoecrab.org
See a detailed diagram of the morphology of a limule
a site on the limules
Page on the limule of the aquarium of the La Rochelle
http://www.mury.com.fr/limule/index.htm
Limule Article on Wiktionary

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