foraminifer

8/13/2019 foraminifer

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For this week's Discussion Board assignment, you need to make a post on the appropriateDiscussion Board forum (organized by type of marine organism) by answering the followingquestions:

On the Web, find a site that has information about one of these four types of marine micro-

organisms that can be found in marine sediment: diatoms, radiolarians,

coccolithophores, or foraminifers. Write a 1-paragraph review of the site, including:

• The title of the site and its complete URL Website address (begins with "http://...")

(NOTE: you cannot use a site already used by any other student, so it pays to get thisdone early!) • Include a photo of the organism within your post (you can download a photo from theWeb, then upload it into your post in Blackboard using the "Insert/Edit Image" icon onthe toolbar but -2 if you use the PAPER CLIP attach icon; to view an instructional videoto see how this is done, click on the "Watch Video" button below) • List at least 2 factoids about the organism (for example, anything that made you say"WOW!") • Any other information about the organism that you found particularly interesting or

unusualPlease make your post answering all questions posed above by Saturday September 14

at noon. Also as part of the assignment, you will need to reply to 2 other students' posts and

rate at least 3 other students' posts by Sunday September 15 at noon. Note that

when make a reply to another student, please include their name in your reply:

Ex of reply: "Hi John, I appreciate your post because it made me...."

This DB assignment is worth 10 points (late posts will be marked down -5 points per day orfraction thereof).

Foraminifers

The website that I found informative and interesting in its description of foraminifers is administered by

The British Geological Survey and can be accessed at: http://www.bgs.ac.uk/discoveringGeology/time/ Fossilfocus/foraminifera.html

According to this site Forminifera are “amoeba-like, single-celled protists (very simple micro-organisms).”

ForaminiferaForaminifera (formally called Foraminiferida) are amoeba-like, single-celled

protists (very simple micro-organisms). They have been called 'armouredamoebae' because they secrete a tiny shell (test) usually between about ahalf and one millimetre long. They get their name from the foramen, anopening or tube that interconnects all the chambers of the test. Fossilisedtests are found in sediments as old as the earliest Cambrian (about 545million years ago) and foraminifera can still be found in abundance today,living in marine and brackish waters.

http://www.bgs.ac.uk/discoveringGeology/time/Fossilfocus/foraminifera.html










One of the first fossilised foraminifera to have evolved is Platysolenitesantiquissimus. It lived about 545 million years ago during the earlyCambrian and has been found in rocks in Wales and in a borehole sunkbelow Oxfordshire. They are agglutinated tubes three or four centimetreslong.

Platysolenites antiquissimus.

The photograph (left ) shows a cross-section of one of the tubes (which isabout two millimetres across) and although it is slightly squashed, theagglutinated sand grains and the tubular structure are clearly visible.

Foraminifera are very small sea organisms that create calcium carbonate (CaCO3)shells to protect themselves. When they make their shells, they incorporate oxygen fromthe ocean, which contains both 16O and 18O, and as a result, scientists can useforaminifera shells to obtain delta-O-18 values and to determine the ocean temperature

at the time of the shell's creation. Using this method, James C. Zachos created a graphof the delta-18-O value over time (1994).

What are Foraminifera?

Foraminifera (‘hole bearers’) or forams for short, are a large phylum of

amoeboid protozoans (single celled) with reticulating pseudopods, fine

strands of cytoplasm that branch and merge to form a dynamic net. They

usually produce a test (or shell) which can have one or more chambers, and

are made of calcium carbonate (CaCO3) or mineral grains or other particlesglued together. The tests are usually less than 0.5 mm in size, but the

largest can be up to 20 cm across. Foraminifera are among the most

abundant and scientifically important groups of marine organisms. The tests

of recently dead planktic foraminifera are so abundant that they form a thick

blanket over one third of the surface of the Earth (as Globigerina ooze on

the ocean floor). Foraminifera are essentially marine- and estuarine-dwelling

protozoans living in all environments from the greatest depths right up to

highest astronomical tide level and from the equator to the poles.

The importance of foraminifera comes from the use of their fossil tests in

biostratigraphy, paleoenvironmental studies, and isotope geochemistry.Their ubiquity in most marine sedimentary rocks, often as large, well-

preserved, diverse assemblages, has resulted in their being the most studied

group of fossils worldwide. Because modern foraminifera have attracted little

interest from biologists, paleontologists have been forced to undertake most

studies, including genetic research, on the living fauna.



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