Morphology of foraminifera

1. A
Seminar on
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April 7, 2017

2.  Introduction
 History
 Morphology
 Wall Structure and Composition
 Chamber Development, Architecture and Shape
 Palaeo-ecology and Its Significance
 Geological Distribution
 Uses of Foraminifera
 Conclusion
 Reference
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3.  Micropaleontology is concerned with microfossils and nanofossils (the latter
being smaller than 50 µm), the study of which must, of necessity, be carried
out using the light or electron microscope. Such microfossils are :-
1- The remains of unicellular and multicellular micro-organisms.
2- The dissociated elements and skeletal fragments of macro-organisms.
 They consist of these types: Foraminifera, Ostracods, Coccolithophora,
Diatoms, Radiolaria and Dinoflagellates.
 Among this, the Foraminifera, ("Hole Bearers") or forams for short, are
single-celled protists with shells which can have either one or multiple
chambers, some becoming quite elaborate in structure.
 Depending on the species, the shell may be made of organic compounds,
sand grains and other particles cemented together, or crystalline calcite.
 Foraminifera are found in all marine environments, they may be planktic or
benthic in mode of life.
 Because of their diversity, abundance, and complex morphology, fossil
foraminiferal assemblages are useful for biostratigraphy, and can accurately
give relative dates to rocks, in petroleum exploration, paleoclimatology etc.
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4.  The name Foraminiferida is derived from the foramen, the connecting
hole through the wall (septa) between each chamber.
 The study of Foraminifera has a long history, their first recorded
"mention" is in Herodotus (fifth century BC) who noted that the limestone
of the Egyptian pyramids contained the large benthic foraminifer
Nummulites.
 In 1835 Dujardin recognised foraminifera as protozoa and shortly
afterwards D'Orbigny produced the first classification.
 The famous 1872 HMS Challenger cruise , the first scientific
oceanographic research expedition to sample the ocean floor collected
so many samples that several scientists, including foraminiferologists
such as H.B. Brady were still working on the material well in to the
1880's.
 Work on Foraminifera continued throughout the 20th century, workers
such as Cushman in the U.S.A and Subbotina in the Soviet Union
developed the use of foraminifera as biostratigraphic tools.
 Later in the 20th century Loeblich and Tappan and Bolli carried out much
pioneering work.
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5. Kingdom : Protista
Phylum : Protozoa
Subphylum: Sarcodina
Class : Rhizopoda
Order : Foraminiferida
Foraminifera are single-celled animals protected by hard shells of different
types of materials (chitinous, calcareous, agglutinatd, and siliceous). They are
microscopic in size, and generally range from 0.1 to 1 mm. (approximately the size of a
grain of sand or smaller) and some are more than that.
Animal consists of:
Cell (Soft parts of foraminifera) has:
Protoplasm (surrounded by membrane)
Protoplasm within the shell (test) = endoplasm (dark and granulous)
contains:
- 1 or more nuclei
- systems for cell-secretion (Golgi)
- systems for gas-exchange (Mitochondria)
- systems for protein-synthesis (Ribosomes)
- fluid or gas filled ‘ droplets’ (Vacuoles)
Protoplasm outside the test = ectoplasm (transparent) forms
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6.  Pseudopodia
Long strings of ectoplasm (2-3 to 20 times test diameter) Can branch very often,
shaping web-like appearance around the test. Surrounded by rather fluid layer.
Diagram showing live benthic foraminiferal style (Brasier, 1980)
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7.  The test of Foraminifera are composed of two different kinds of material :-
a) one kind is secreted by the organism
b) the other consist of foreign particles gathered from bottom
sediments and cemented together to form agglutinated test
Some of them are as follows :-
 Chitinous wall: Composed of chitin, thin and transparent, present in fresh-
water benthic foraminifera. e.g. Chitiodendron fronconianom.
 Agglutinated wall: Only feature for benthic----foraminifer builds its test wall
by cementing together exogenous grains (e.g. sand grains, oolites, fine grains
of calcite or sponge spicule) by carbonate mineralization. Wall is a simple
layer that grades from fine grains inside to coarse grains outside. e.g.
Rhabdammina.
 Calcareous (Ca CO3) wall: Present for both benthic and planktonic
foraminifera: (hyaline or porcelaneous). e.g. Globugerina.
 Hyaline/glassy wall: Transparent, perforate, crystals are radial, with lamellae
(laminations) that separated by organic layers. e.g. Rotalina.
 Porcelaneous wall: Shiny, smooth, crystals randomly arranged. e.g.
Miliolina.
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8. Fig:-Examples of wall structures in foraminifera (Brasier, 1980)
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9.  The test of Foraminifera may consist of single chamber called
unilocular (monothalamus) which chamber growth proceeds gradually
along with protoplasmic growth. e.g. Lagena or of two or more
chamber called multilocular (polithelamous) e.g. Nodosaria.
 In multilocular forms protoplasmic growth is gradual but test growth is
periodic and the addition of new and larger chamber will takes place in
different way to produce different growth planes. They are :-
 Planispiral - When chambers arranged spirally around an exis of
coiling and spiral lies in a single plane. e.g. Nodosaria.
 Trocospiral - When the spiral does not lie in one plane, but progress
up the axis of coiling the chamber arrangement becomes helicoids.
e.g. Ammonia.
 Uniserial - Arranged in a single raw or arcuate if curve and rectilinear
if a staraight series. e.g. Dentaline
 Biserial - Chambers are arranged in two raws. e.g. Textularia.
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10. Contd
…
 Non-laminar - When there is no overlap of previous chamber walls by the
new wall. e.g. Fusulinina.
 Multilaminar – If overlap occurs, thin section will reveal the layers of
successive walls. e.g. Rotalina.
 Whorl or Coil – When a series of chambers is arranged spirally or coiled
about an axis.
 Involute – The majority of the previous coil are hidden and shows ventral
side. e.g. Cilicidis.
 Evolute(convolute) – Majority of the previous coil are visible, shows dorsal
side.
 Umbo – When central depression (umbilicus) are filled with secondary
material.
 Proloculus – The initial chamber of foraminifera.
 Diamorphism – A significant feature which exhibit two distinct
morphological character i.e. megalosphiric and microsphiric.
e.g. Nummulites.
 Dextral and Senistral – Clockwise and anticlockwise coiling.
 Suture – The joint of each whorl with the other.
 Aperture – Opening found in the wall of the final chamber.
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13.  It has been estimated that more than 80,000 species of
Foraminifera are described in the literature.
 Foraminifera are adapted to all aquatic habitats, most in marine
waters, but some can exist in salt or brackish water and the
member of one family (Allogromidae) live in fresh water.
 Most are typically slow moving bottom dwellers and some are
pealgic.
 Foraminifera are usually extremely sensitive to environmental
condition such as temperature, salinity, bathymetry etc. and
therefore their study is significant to understand the
palaeoecological condition of the time of their living.
 The benthonic forms are indicative of the temperature, salinity,
depth and bottom conditions while the temperature, bathymetry
and paleaocurrent patterns are indicated by planktonic forms.
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15.  Foraminifera are thought to have been present in the Pre-
cambrian seas, but as yet no undepted fossils of this order have
been described from rocks older than the Cambrian.
 The Foraminifera found in the sediments are of all the ages
ranging from Cambrian to Recent.
 They made their first appearance in Cambrian and comparatively
rare till Carboniferous, but they became prominent and of great
geological importance during uppper Carboniferous and Permian.
 Again during Triassic they become less abundant, but during
Jurassic and Cretaceous they are represented by large numbers,
they reached the maximum developed during Tertiary and
Recent.
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16.  Because of their diversity, abundance, and complex
morphology, fossil Foraminiferal assemblages are useful for
biostratigraphy, and can accurately give relative dates to rocks.
The oil industry relies heavily on microfossils such as forams to find
potential oil deposits.
 Calcareous fossil Foraminifera are formed from elements found in
the ancient seas they lived in. Thus they are very useful in
Palaeoclimatology and Palaeoceanography.
 They can be used to reconstruct past climate by examining
the stable isotope ratios of oxygen, and the history of the carbon
cycle and oceanic productivity by examining the stable isotope
ratios of carbon.
 Foraminifera can also be utilised in Archaeology in the
provenancing of some stone raw material types. Some stone types,
such as limestone, are commonly found to contain fossilised
Foraminifera.
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17.  Foraminifera are abundant in most marine environments so only small sediment
samples (a few grams) are needed to obtain statistically significant numbers of
microfossils to perform environmental analysis.
 They are sensitive to environmental change and their mineralized shells
normally get preserved in the sediment after the death of the organism.
 The quantitative importance of Foraminifera is large and they may constitute a
major portion of the Biomass in many marine ecosystems. They must therefore
be considered as one of the most significant organism groups living today.
 Some recent studies indicate that Foraminifera are not only a group of great
ecological importance as food organisms for fish and invertebrates, but also
play an important role in the turnover of nutrients and energy in the sea.
 They are extremely useful in Applied Geology, such as in history of Climate,
Stratigraphy and in Oil Prospecting.
 Foraminiferal analyses of dated sediment cores represent a quick and cost
efficient way to evaluate possible environmental differences between present
and pre-impact (reference) conditions without previous knowledge of the area
being examined.
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18. BOOKS:
 2008 Dr. P. Jain and Dr. M.S. Anantharaman “PALAEONTOLOGY”
Vishal Publishing co. Jalangdhar- Delhi, Pp (58-69).
 2008 P. K Mukherjee “ A TEXTBOOK OF GEOLOGY” World Press
Private Limited, Pp (307 to 309)
 1998 Dr. P. K. Kathal “MICROFOSSIL AND THEIR APPLICATION”
CBS Publishers and Distributers, Pp (50-71).
 1970 Rhona M. Black “ THE ELEMENTS OF PALAEONTOLOGY”
Syndics of the Cambridge University Press, Pp (234-239).
WEBSITE :
en.wikipedia.org/wiki/Foraminifera
www.ucl.ac.uk/GeolSci/micropal/foram.html
www.mans.edu.eg/FacSciM/english/courses/
ucl.ac.uk/EarthSci/people/fadel/Benthic
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