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Foraminifera

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Foraminifera
Foraminifera.jpg
Scientific Classification
Orders
  • Allogromiida
  • Carterinida
  • Fusulinida - extinct
  • Globigerinida
  • Involutinida - extinct
  • Lagenida
  • Miliolida
  • Robertinida
  • Rotaliida
  • Silicoloculinida
  • Spirillinida
  • Textulariida
  • incertae sedis
  • Xenophyophorea
  • Reticulomyxa

The Foraminifer, which is also known as the forams for short, is a large group of amoeboid protists. They contain reticulatin pseudopods, and fine strands of cytoplasm that branch out to form a dynamic net. Forams produce a shell or test, that either consist of one or more chambers. Scientist have discovered about 275,000 species, both fossil and living. They average in size from 0.05 millimeter to the largest recorded 19 centimeters. Data proves that Foraminifera are closely related to cercozoa and radiolaria, all together they make up the group Rhizaria.

Anatomy

SEM micrographs of four benthic foraminiferans (ventral view) from the USGS. Clockwise from top left: Ammonia beccarii, Elphidium excavatum clavatum, Buccella frigida, and Eggerella advena.

Foraminifera are primarily marine based, although many have been known to survive in brackish conditions, fresh water, and some even in damp rainforest soil. The foraminifera cell is divided up into granular endoplasm and transparent ectoplasm. The pseudopodial net that is contained in the cell maybe emerge through an opening or through many perforations in the test, and is specified by its small granules streaming in all directions. Pseudopods are used for locomotion, anchoring, and capturing food which contains small organisms such as diatoms and bacteria. A large amount of forms have an unicellular algae as endosymbionts and diverse lineages such as green algae, red algae, golden algae, diatoms, and dinoflagellates. Many of the forams known are kleptoplastic (plastids from algae are sequestered by a host organism), which then retain chloroplasts from algae to conduct photosynthesis.[1]

Reproduction

Forams can live up to a couple of years. Forams with multichambered cells add on larger and larger chambers as they grow. This allows them to break apart themselves into many small pieces that do not contain shells. They will then grow flagella and swim away. It is thought that for every other generation of Foraminferas they will switch off between sexual and asexual. This then leaves things like many adults to have different body forms then their offspring.[2]

Ecology

Electron micrograph of foraminifera.

The foraminifera life-cycle includes an alteration between haploid and diploid. Even though both are very different things they both are very similar in form. Haploid has a single nucleus, and divides itself so that it can produce many gametes which normally have two flagella. The diploid however is a multinucleate, and use meiosis fragments to produce new gametes.[3]

Because of the foraminifera's diversity, abundance, and morphology, they can be used for biostratigraphy, and therefore can accurately give dates on rocks. Industries such as oil, relies much on microfossils to find potential oil deposits. Many fossils such as the calcareous fossil, was formed in seas that they have previously lived in. this gives scientists a useful tool in paleoclimatology and paleoceanography. Scientists use these fossils to conduct past climates by examining the ratios of oxygen, carbon cycle, and oceanic productivity. They may also use the planktonic forams to re-create oceanic currents. Another major thing these fossils can do is reveal what type of ancient marine sediments were deposited.

Gallery

Related References

  • [4] Wikipedia
  • [5]Protists
  • [6]Wikimedia commons


See Also