———-Foraminifera———-

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« LE MONDE DES FORAMINIFÈRES »

Some figures on a miniature animal world unknown :
– les origines de ces animaux sont estimées à environ 550 millions d’années et leurs tailles les plus courantes vont de 0.25 mm to a few mm (there are smaller and giants that can reach 15 cm et c’est le cas des nummulites)
– Herodotus (5 centuries BC), Strabo (- 57 + 25) or Pliny the Elder (+ 23 + 79) avaient déjà repéré ces petites bêtes en grande quantité dans les pierres calcaires des pyramides d’ Egypte, more en 1758, there was still talk of a score of foraminifera (10éme édition de Systema Naturae du suédois Ch. The Linnaeus).
– This science – la micropaléontologie – ne prit un envol réel que vers les années 1920 pour les besoins de la recherche pétrolière et aujourd’hui plus de 50.000 espèces de foraminifères ont été recensées depuis leur apparition sur terre et l’on en compte 5.000 to live today.
– 3 milliards d’individus au m3 dans certaines roches calcaires du bassin parisien. Example : the stone of Mount Liard Berny in Oise.

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But who are these foraminifera ?
They are single-celled organisms of the animal world.
A single cell and a shell, is simple (ostensibly).
This shell called "test" (pronounced ty) protects the cell which is divided into endoplasm inside and outside ectoplasm.
pseudopodia, long thin filaments more or less anastomosing (joined together), used to capture food and to move.
This test can take absolutely beautiful architectural forms in a variety of materials, but the majority of foraminifera secrete limestone required for the formation of their shells.
These shells are usually arranged in several lodges (Rooms) building itself during the growth of the individual. These boxes are arranged spiral, rectilinear, wound etc ... and communicate via a small opening called the foramen where Latin name foraminifera.
Some foraminifera, in addition to being good architects, are also good entrepreneurs. They can assemble different materials borrowed from the natural biotope, grains of sand, spicules d’éponge, mica flakes and other miscellaneous debris by secreting a kind of glue cement to form an agglutinated shell.
To ensure the rigidity of their shell, the larger foraminifera have developed very sophisticated systems to build additional walls. They did not need a computer to find before us the advantages and strength of the forms of corrugated iron, Corrugated cardboard box or egg.

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Where and how to live foraminifera ?
Foraminifera living in the marine environment in all the world's seas. (Some examples are shown here)
What are icy or tropical, the seas are the living place for particular types of foraminifera while noting however that in the middle tropical species have larger sizes.
There are also some foraminifera in salt lakes deserts. (Libya, Egypt)
foraminifera are classified into two distinct groups : planktonic and benthic.
The first traveling with the currents, mates bind on the merits of different media (rock, seaweed) and eventually move a few centimeters per hour using their pseudopodia.
They feed on microscopic algae, microorganisms or various organic materials.

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Evolution
Small in size, with a very short lifetime (weeks), but a huge fertility (once but for thousands of individuals), the different types of foraminifera became over millions of years of their existence and evolution of geological markers.
Emptied of all living substance after reproduction, tests fall to the sea floor, accumulate on large thicknesses (5 to 6 cm per century at times) and change over time in limestone.
The Normandy cliffs eg, are former seabed largely consist of planktonic foraminifera.
Into the abyss, beyond 5.000 m, calcareous planktonic foraminifera tests (Type globigerina mostly), are dissolved by the pressure and become sludge. Only clumped shells can withstand.
At the time of Lutétien (-49 – 41 million years), the accumulation of benthic foraminifera produced rocks that man has used the Middle Ages to the Renaissance building churches, many castles and monuments of Paris. The foraminifer (Nummulite laevigatus) was the shape of the Liard, this royal copper coin that was worth a farthing, hence the name stone Liard previously cited.

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It is understandable that the different species that have succeeded and which have evolved over 550 million years of existence, a source of information for each geological period. The study of fossil foraminifera in each stratigraphic floor, by precision and remarkable safety is useful in oil exploration in particular.
This is arguably the economic activity, early as the 1920, contributed to the development of micropaleontology.

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Unknown to most of us, these animalcules are also being studied for the feasibility of some projects such as openings of tunnels, Underground parking, etc…
Tunnel under the Manche, which is a modern technical and scientific feat, must among other realization foraminifère to a very specific type. The success of digging involved to perform in a geological layer of chalk called "blue chalk the Cenomanian" (- 95 million years). The boundaries between the blue and the chalk layer the upper and lower gray chalk is not detectable, the TBM, énorme machine, technological monster, has traced a small foraminifera few hundred microns, the "Rotalipora reicheli" feature from the top of the blue chalk.
Many other applications could be described and it would probably 20 volumes of Larousse to study the animal world, his characteristics, his experience and his future.

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I am not a scientist, just an amateur, curious, a contemplative of all things. I can open up a tiny door in the world of foraminifera and say thank you to those and to those who have aroused my curiosity. ( a big thank you especially to Mr. J. P Margerel. Retired from the University of Nantes who kindly devoted part of his time to me to discover this unknown world )

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Now when you walk on a beach, if you hear that one shouts :
« attention ! I'm below you crush me ! » ……. it will be perhaps a distressed foraminifera test.
Walk on tiptoe ..............

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Bernard Remaud
Bibliography
– BIGNOT G., (2001) - "Introduction to Micropaleontology". Coll. Geosciences, Gordon & And Breach.
– DEBENAY, PAWLOWSKI et DECROUEZ (1996) - "Current foraminifera". Masson Ed.
– THE Y CALVEZ. (1977) - "Micropaléontologie Notebooks, T1 et T2, Cuba ". CNRS
– MARGEREL JP.- ( our personal meetings in Marseille )
– NOUET R. (2001) - "Do you know foraminifera ? » (comm. lost.).
– ROBERT WYNN JONES. (1994) – « The Challenger Foraminifera ». Oxford University Press.
– CLEAT Ph. (2002) - "Paris MNHN, Alcide from Orbigny, the New World to the past of the world ". And Nathan.
– VENEC PEYRE-M-Th. (2005) - "The unpublished boards foraminifera". Publication MNHN, Paris.

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Photos Bernard Remaud. Reproduction prohibited without authorization

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