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Benthic foraminifera
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- 2. What are Foraminifera: •with characteristic net-like pseudopodia called reticulopodia • organic or shell-like, agglutinated or secreted outer protective layer, called a test single-celled organisms (protists) Such organisms are classified in the Superkingdom of Protists or Protista with a complex cell (Eukaryotes), and genetic material within a cell nucleus. Cytoplasm is extruded as pseudopods through the aperture and any perforations in the test
- 3. Foraminifera are placedin the “Cercozoa”. Cercozoans are amoebae with filose pseudopodia, often living within hard test
- 4. Most foraminifera growan elaborate, solid calcite skeleton made of a series of chambers. The complexity of their shell structures and their evolution in time the basis of their geological usefulness as fossils. Most foraminiferal tests are sand-sized (>61 mm in diameter)
- 5. Both living andfossil foraminifera • inhabited the oceans. • They are extremely abundant in most marine sediments • in many different environments, from live in marine to brackish habitats • near shore to the deep sea, • and from near surface to the ocean floor • Some foraminifera live in oligotrophic reef associated with algae.
- 6. Composition of fossilforaminifera tests varies from • calcareous secreted from calcium carbonate. • agglutinated (organic compounds, sand grains and other particles cemented together, or crystalline calcite)
- 7. The test iscommonly divided into chambers which are added during growth The size of the test is associated with amount of the cytoplasm. Feeding adds to the bulk of the cytoplasm, therefore, the test has to enlarge. Foraminifera have developed several strategies for test enlargement during ontogeny contained growth unilocular test The test is thought to reduce biological, physical and chemical stress continuous growth Bilocular test simple septate growth multilocular complex septate growth Complex multiocular test These growth patterns result in a very diverse variety of test morphologies
- 8. the simplest formsare open tubes or hollow spheres Both living and fossil foraminifera come in a variety of shapes and sizes Spirillina Planispiral, evolute, undivided tube Lagena Undivided chamber reticulation
- 9. a: aperture; ad:adapertural depression; li: lip; tp: toothplate with its serrated margin. Loxostomina. A-B: Globoturborotalites Carpenteria cancellation perture terminal Secondary aperture Main aperture aperture
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- 12. What are fossilforaminifera? Fossils can be microscopic or a few centimeters long They have inhabited the oceans for more than 500 million years and found fossilised in most type of sedimentary rocks. Most foraminifers construct tests (shells) covering the cell body. Fossil foraminifera are the remains of their tests (shells). Fully grown individuals range in size from about 100 micrometers to almost 20 centimeters long.
- 13. because there canbe thousands of specimens in a small sediment sample. relatively small size of tests (shells) makes foraminifera For, biostratigraphic, palaeo/environmental, palaeoceanographical and palaeoclimatological reconstruction or petroleum exploration applications much more useful than larger fossils
- 15. The study ofthe sequence of sedimentary rock strata is the main source for scientific knowledge about the Earth’s history, including biostratigraphy, paleogeography, paleoclimatology and the history of life
- 18. • Orders offoraminifera (underlined include larger foraminifera (see BouDagher-Fadel, 2008). In red includes planktonic foraminifera) • ALLOGROMIDA: organic wall, usually 1 chamber; Cambrian-Recent • ASTRORHIZIDA: agglutinated, organic cement, usually 1 chamber or branching tube; Cambrian- Recent • LITUOLIDA: agglutinated, organic cement, many chambers, usually planispiral spiral; Cambrian- Recent • TROCHAMMINIDA: agglutinated; organic cement, many chambers, usually trochospiral; Cambrian- TEXTULARIIDA: agglutinated, low Mg-calcite cement; Cambrian-Recent • FUSULINIDA: microgranular calcite; many complex chambers; Silurian-Permian • MILIOLIDA: high Mg calcite, imperforate, many chambers (porcellaneous, no pores); miliolid chamber arrangment; Carboniferous-Recent • CARTERINIDA: low Mg calcite, hyaline, pores or no pores; spicules, plani- or trochospiral; Tertiary- Recent (?) • SPIRILLINIDA: low Mg calcite; hyaline; single crystal; spiral; Jurassic-Recent • LAGENIDA: low Mg calcite, hyaline; pores, 1 or many chambers, uniserial or planispiral; monolamellar; Carboniferous-Recent • BULIMINIDA: low Mg calcite; hyaline; pores; many chambers; bilamellar; toothplate; Triassic?- Recent • ROTALIIDA: low Mg calcite; hyaline; pores; many chambers; bilamellar; trocho- or planispiral, annular, irregular; Triassic-Recent • GLOBIGERINIDA: low Mg calcite (aragonite in few extinct forms); pores; many chambers; bilamellar; radial crystals (PLANKTON); Jurassic-Recent • INVOLUTINIDA: aragonite; 2 chambers - 2nd tube • ROBERTINIDA: aragonite; pores; many chambers; trochospiral; Triassic-Recent • SILICOLOCULINIDA:opaline silica, no pores; chamber arrangements as in miliolids; Miocene- Recent • Genetic evidence suggests strongly that Allogromida (‘naked’) and Astrorhizida (agglutinated) are one order.
- 19. Life strategy Float inthe surface of the open ocean and sea water column Wide distribution Rapid evolution + short stratigraphic range = excellent index fossil Benthic foraminifera Live attached or free At all depth marine, brackish and freshwater habitats sea-floor Small Larger Planktonic foraminifera
- 20. • Benthic foraminiferaare bottom dwelling forms that can be either sessile or vagile. Benthic foraminifera •Vagile (mobile) foraminifera are free to move along the sea floor and/or in its substrate Cassidulina •Sessile foraminifera are permanently attached or fixed (not free-moving) Ammobacculites Miniacina
- 21. Benthic foraminifera Small benthicforaminifera Larger benthic foraminifera include two major groups of foraminifera occur abundantly in the shelf regions of most tropical and subtropical shallow marine, especially in carbonate-rich, environments live, attached or free, at all depths, in most marine environments, as well as in brackish, marginal marine environment with low alkanity. with complicated internal structureswith simple internal structures
- 22. •Benthic foraminifera arean important component of the deep-sea biomass in the present oceans, adapted to its cold, dark, and extremely oligotrophic environments. •Larger benthic foraminifera are important shallow marine rock builders • Faunas are highly diverse, and many species have a cosmopolitan distribution. •In addition to their interest as indicator species living in the largest habitat on earth, their tests have been used extensively in isotope and trace element analysis aimed at reconstruction of past environments.
- 25. Larger Foraminifera withtest sizes from 2mm up to 13cm are characteristic organisms inhabiting shallow water subtropical and tropical environments today.
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- 30. Two main factorsacting as single gradients regulate the distribution of larger foraminifera within coral reef complexes. Larger foraminifera prefer clear, nutrition depleted water as can be found in the surroundings of coral reefs. All house symbiotic microalgae and are thus restricted to the photic zone (-130m), getting independence from food resources outside the cell. House symbiotic algae
- 32. Allogromia has a proteinaceoustest with a single chamber. The oldest fossil foraminifera, from the Cambrian, are simple agglutinated tubes.
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- 37. Fusulina rice-grain shaped testsand evolved into numerous widespread species during the Permian but large forms went extinct at the end of that period when a worldwide mass extinction also eliminated most other reef dwelling organisms.
- 42. BouDagher-Fadel, M.K., 2008. Evolutionand Geological Significance of Larger Benthic Foraminifera , Developments in Palaeontology and Stratigraphy, 21, Elsevier, Amsterdam, pp 544. Haynes, J.R., 1981. Foraminifera. MacMillan, London, pp 433.
Editor's Notes
- #9 Chamber: cavity containing cytoplasm. Chambers separated by septa; connected by foramina (holes) in septa. Foramen in last chamber is called aperture External lines of junction of chamber walls and septa: sutures
- #12 Chambers enveloping earlier ones: involute Chambers leaving earlier ones visible: evolute Disk-shaped spiral where two sides look the same: planispiral Disk-shaped spiral with one evolute, one involute side: trochospiral
- #22 Calcareous microgranular and porcellaneous tests into large complex tests associated with reefs. These groups of large species became abundant when reef environments were widespread, then suffered major extinction when world climate changed and reefs were decimated