Anatomy

Introduction

I chose to look at the anatomy of foraminifera because they are enormously abundant in terms of species and morphology, which I personally found very interesting examining the vast variety of different anatomies.

Brief Overview on Forams

Foraminifera are a group of single celled protists. There is approximately 4,000 different species of forams dwelling in the Earth’s oceans or on the sea floor, some however have been found in soils. This vast number of species along with the various habitats they are found in has lead to their anatomy being very varied.

Anatomy

The main anatomical feature of foraminifera is the shell, which are also known as tests. Refer to figure 1 for an image of four different types of foram tests.

Fig 1. Foraminifera tests.

These tests are generally made of calcium carbonate (CaCO3), but they can also consist of silica, mineral grains and/or other substances glued together. The tests are usually less than 0.5mm. However the largest recorded test was measured at 18cm. The tests are commonly divided into chambers, which are added during the growth of a foram. The simplest types of these chambers are hollow spheres or tubes. The tests are either multilocular (they have multiples chambers) or unilocular (they have only a single chamber).

Most foraminifera also possess a rather unusual anatomical feature called reticulopodia. See figure 2.

 Fig 2. foram pseudopodia

These reticulopodia are complex microtubule pseudopodia. The function of this is to produce an external net to entrap food. These reticulopodia are similar to those of an amoeba, however the foram pseudopodia are thinner and more numerous.

Foraminifera have another main anatomical feature called an aperture. In terms of foraminifera the aperture is primarily the opening cavity of the test/shell.

 

 

Fig 3. Foram aperture’s

Figure 3 shows the various main types foram apertures.

1. Open end of tube
2. Terminal radiate
3. Terminal slit
4. Umbilical
5. Loop shaped
6. Interiomarginal
7. Interiomarginal multiple
8. Areal crbrate
9. Phialine lip
10. Bifid tooth
11. Umbilical teeth
12. Umbilical bulla

 

Uses of foraminifera anatomy in modern day

The test of foraminifera can be very useful to modern day scientists. Most species of foraminifera are sensitive to changes in their environment in terms of salinity and temperature. This sensitivity allows preserved tests to be very useful indicators for environmental change on both a local and global scale.

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References

1)    University of California Museum of Paleontology

www.ucmp.berkeley.edu

2)    London’s Global University

www.ucl.ac.uk

3)    Jan Pawlowski, Maria Holzmann, Jaroslaw Tyszka (2013). New supraordinal classification of Foraminifera: Molecules meet morphology,

Marine Micropaleontology, Volume 100

4)    Simon J. Beavington-Penney, Andrew Racey (2004). Earth Science Review, 219-265

5)    Foraminiferal Research at Byrd Polar Research Centre

http://www.bprc.osu.edu/geo/projects/foram/home.htm