Foraminifera is derived from the Latin term “Foramen,” which means “hole-bearing.” They are tiny, single-celled creatures with a fossil record dating back more than 500 million years.
In fact, fossil records of planktonic organisms have been found in Europe’s Tethys and epicontinental basins dating back to the Mid Jurassic era, with the oldest types of Foraminifera being benthic organisms.
Despite being only a unicellular organism, forams construct intricate shells around themselves out of minerals found in saltwater.
These shells have gathered in sediment layers under the open ocean’s seabed and in areas where the ocean formerly swamped the lands for long periods of time.
Moreover, several Foraminifera species have been demonstrated to be mollusk and other foram parasites, while thanks to their species, researchers have educated themselves about Earth’s temperature long before humans ever roamed the globe by investigating the shell chemistry of these ancient forams—and obtained information on how climate has altered in the past.
Let’s take a deeper look at the details behind this interesting species and its life.
Foraminifera Species: An Overview
The Foraminifera species were discovered for the first time in the fifth century. They are unicellular protozoa that are typically seen in marine habitats, with a lot of them being way larger in size.
Foraminifera organisms are distinguished by the appearance of shells called ‘tests,’ although they are single-celled, microorganisms.
A few of the forams have been proven to develop associations with algae and cyanobacteria to survive, based on their environment.
Nevertheless, most of these organisms are free-living creatures that subsist on a range of food material that exists in the surrounding environment.
Although they have many traits in common, Forams are split into two primary groups: benthic (living on the seabed) and planktonic (drifter).
Foraminifera species, being amongst the most common creatures in marine settings, play an essential part in these ecosystems (in the trophic chain, for example) and they also give crucial data about the ages of sea sediments In addition to the general environmental state of the ecology.
Some of the forams are the following:
- Bulloides Globigerina
- Ruber Globigerinoides
- Inflata Globorotalia
- Sacculifer Globigerinoides
- Menardii Globorotalia
- Pachyderma Neogloboquadrina
Foraminifera: A Historical Overview Of The Species In The Scientific Field
Foraminifera was first mentioned by Herodotus in the fifth century BCE when he mentioned them as part of the granite that formed the Great Pyramid of Giza.
These are now classified as members of the genus Nummulites. Strabo saw the same foraminifera in the first century BCE and argued that they were the leftovers of lentils left by the workmen who erected the pyramids.
Under the microscope, Robert Hooke noticed a Foraminifera, which he described and drew in his 1665 book Micrographia. This book also has the earliest known image of a foraminifera shell.
At the beginning of the 18th century, Antonie van Leeuwenhoek characterized and drew foraminiferal tests as minute cockles; his depiction is identifiable as Elphidium.
Forams were first classified as a genus, Nautilus, because of their resemblance to some cephalopods.
Lorenz Spengler discovered in 1781 that forams contained holes in their septa, which gave rise to the group’s name. Spengler also observed that the septa of forams arced in the opposite direction of those of nautili and lacked a nerve tube.
In his 1826 paper, Alcide d’Orbigny classified them as a group of minute cephalopods and observed their unusual morphology, interpreting the pseudopodia as tentacles and noting the greatly reduced (really, missing) head.
He called the group ‘foraminifères,’ or “hole-bearers,” because members of the group, unlike nautili or ammonites, had holes in the divides between compartments in their shells. Dujardin discovered the protozoan origins of foraminifera in 1835.
A few years later, in 1852, d’Orbigny published a categorization scheme that recognized 72 taxa of foraminifera and categorized them based on their shape—a method that garnered harsh criticism from colleagues.
H.B. Brady’s 1884 monograph documented the Challenger expedition’s foraminiferal discoveries.
Brady identified ten families with 29 subfamilies, with minimal respect for stratigraphic range; his taxonomy emphasized the concept that many diverse features must distinguish taxonomic groupings, and as such, agglutinated and calcareous taxa were placed in close connection.
This overarching categorization approach would last until Cushman’s work in the late 1920s.
Cushman regarded wall composition as the single most essential property in foraminifera classification; his classification became widely accepted but was criticized by others for being “not physiologically sound.”
Cushman’s approach remained the dominant classification scheme until Tappan and Loeblich’s 1964 classification, which classified foraminifera into the general categories that are still used today, based on the microstructure of the test wall.
These groupings have been shifted according to several higher-level categorization methods.
Pawlowski’s (2013) use of molecular systematics has largely corroborated Tappan and Loeblich’s categories, with some determined to be polyphyletic or paraphyletic; this work has also contributed to the identification of higher-level connections among key foraminiferal groups.
Foraminifera normally forms a test, or shell, with one or more chambers, some of which can be rather complicated in construction.
Calcium carbonate (CaCO 3) or agglutinated silt particles are often used to make these shells. Over 50,000 species have been identified, including both living (6,700–10,000) and extinct (6,700–10,000) as well as fossil (40,000).
They are typically smaller than 1 mm in size, although some are significantly bigger, with the biggest species reaching up to 20 cm in length.
In current scientific English, the term Foraminifera is both singular and plural (regardless of its Latin source) and is used to describe one or more specimens or taxa: its singular or plural meaning must be decided by context. In these circumstances, Foraminifera is often composed of small subunit ribosomal DNA.
Foraminifera Species: Classification
Protista Kingdom: The kingdom Protista are single-celled eukaryotic organisms (and also tiny communities) that are usually seen in watery settings, terrestrial environments, and as parasitic organisms in certain hosts. Some of these organisms also have symbiotic interactions with other creatures.
Subkingdom: Protozoa, which some sources name a kingdom, is made up of unicellular eukaryotic organisms that can survive as independent creatures or as parasites.
These protozoa are frequently seen in all places around the world in different damp or watery settings, feeding on organic compounds, other microbes, detritus, or organic tissues.
Phylum: Sarcomastigophora is a group within the Protista kingdom, the organisms that belong to this category are either single-celled or organisms that live in colonies and which can be capable of photosynthesis or heterotrophic in nature. Species of this category have motility structures such as flagella, pseudopodia, or even both.
Subphylum: As members of the Sarcodina group of organisms, they are protozoans that walk with pseudopodia.
They are unicellular organisms that live in a variety of settings and utilize their pseudopods both for eating (catching and swallowing food) and movement.
Rhizopoda: A superclass of members distinguished by their pseudopodia.
Granuloreticulosea Class: Distinguished by anastomosing pseudopods that aid in the development of the external tests.
Forams are either planktonic or benthic in marine environments. Benthic Foraminifera is a bottom-dwelling organism and hence lives on the seabed.
They may be seen in wetlands and abyssal plains, wherein they wander around and eat with their pseudopodia. This group is thought to have around 4,000 species these days.
Aside from the enormous number of benthic organisms found on the sea bottom, investigations have revealed that a few of the organisms live in seafloor sediments, macroalgae, and stones.
While not as common as germs, they’ve been demonstrated to be widespread enough to form part of the trophic chain.
For example, in their habitat, they have become a food supply for species such as isopods, tiny fish, and sea snails, among others.
Planktonic organisms are the other kind of Foraminifera seen in aquatic habitats (Planktic foraminifera). This species, in contrast to benthic forams, move across water canals at varied sea levels and are hence known as drifters. Approximately 40 planktonic types have been described so far.
Planktonic Foraminifera, like benthic organisms, does well in marine conditions. They employ their pseudopodia so as to grab and trap their meal (e.g.phytoplankton).
A few of the organisms have been seen forming symbiotic partnerships with other creatures, like microalgae.
Symbiotic connections are often developed between the bigger forams types and microalgae. In this interaction, the microalgae live inside the organism’s ‘test’ or shell construction, hence why they are called endosymbiotic.
As shown in a growing body of research, these forams have an intricate esoteric structure that encourages this connection, in combination with their huge size that enables them to accommodate the algae.
This symbiotic association can also be established with red cyanobacteria, diatoms, chlorophytes, and dinoflagellates, in addition to microalgae.
Although certain organisms (particularly bigger ones) create co-existing connections with other creatures, it is important to note that they continue to use their web-like pseudopods to capture and gather food material.
Furthermore, the dwelling organisms (for example, algae) are isolated from the host’s digesting activity (Forams).
Therefore, experts are still trying to figure out how Foraminifera profit from this association. Nevertheless, other research proposes that they utilize the food substances if no other food is available.
Planktonic Foraminifera has been seen to exist in the euphotic zone, which is the one that is near the surface of the waters, throughout their early years of development. As they develop in size, they begin to migrate to deeper levels.
Certain forams have been detected in coastal and inland habitats, as well as land and coral environments, in addition to aquatic ecosystems.
Foraminifera Species: Other Features To Know About
Foraminifera species, as previously stated, are tiny single-celled creatures that are typically seen in marine habitats.
Nevertheless, certain investigations have revealed that a few of the organisms may end up being 15 cm long. The size, on the contrary, is mostly determined by the kind or type of Foraminifera.
Benthic species, for example, which is typically found at lower sea levels, can vary in size from 100um in width to a few centimeters in breadth. Planktonic organisms, however, do not grow more than 600um in girth.
Certain cells contain a single core, while others have several centers within an individual cell, rendering them multi-nucleated cells.
Foraminifera organisms have cytoplasmic projections described as pseudopodia as they are also members of the class Granuloreticulosea.
Their pseudopodia are slimmer and much more in number than those of amoebas and are frequently called reticulopodia. This feature facilitates the creatures’ ability to snare and catch their prey.
Aside from pseudopodia (reticulopodia), the existence of shells is another distinguishing feature of Foraminifera organisms.
It is an essential trait in microbiology and marine science which has been used to classify species based on the shape of their shells (tests).
Moreover, Foraminifera is categorized into fifteen orders in total depending on their shells (tests) form. And whilst these shells consist of secreted calcite in seven of the classes, aragonite or opaline silica is found in the remaining eight.
There are also compositional variations among benthic and planktonic versions. The shells in benthic species are mostly composed of calcite, aragonite, and, in certain circumstances, silica.
The tests can also be agglutinated, which means that quartz as well as other inorganic materials are kept together by a calcitic or organic ingredient. No matter what the subject is, these shells are usually ornate and lengthy.
Calcite and aragonite are the tests for planktonic species. In comparison to the tests of benthic forms, these ones have globular compartments that facilitate floating between these forms.
As a result, the overall structure and anatomical features of various tests may be used to define their environment.
Once those organisms die, their tests or shells drop to the seafloor and may feed on the already existing slime (foraminiferal ooze).
Chamber Formation In The Tests Of Planktonic Foraminifera
The cytoplasm is crucial in the development of chambers. Layers of cytoplasm are important in the formation of the cytoplasmic membrane, which then leads to the formation of the primary organic membrane (POM) and calcite accumulation.
The chambers are then created by the creation of calcareous bilamellar surfaces on the inner and outer edges of this membrane.
Pores are generated in specific sections of the test wall at the beginning of the procedure, leading to the microperforated pores typically connected to these shells.
In fact, the mature type’s shell may have from 10 to 20 chambers. Based on the variety, research has revealed that planktonic species add a new chamber each day, allowing them to develop at a pace of roughly 25% each day in girth.
And based on the way the shells’ components are added, the result of each shell pattern has varied. A few of the development patterns in play are the following:
- Trochospiral development is characterized by chambers that spiral along the development axis as they deviate from it. As a consequence, the test has a distinct involute spiral but also involute umbilical edges.
- Inverted trochospiral development – During the initial phases of production, the chambers seem to be either biserial or triseria. Subsequent phases, on the other hand, are distinguished by enrolled biseries that can be coiled to produce a tight and involute trochospire.
- Planispiral development is distinguished by chambers that coil parallel to the growth axis. Unlike trochospiral development, though, these chambers don’t really deviate from the axis. Finally, the test is biumbilicate and has matching and equal spiral and umbilical sides.
- Streptospiral growth occurs when the chambers coil in sequentially shifting planes. The final globular chamber may expand toward this umbilical side in rare situations.
Chambers in certain species may be placed in one or more lines in a consistently superposed succession.
Foraminifera cells, being eukaryotes in nature, have the below organelles:
- Nuclei: A cell may have a single nucleus or numerous nuclei.
- The Golgi complex
- Endoplasmic reticulum (ER)
Reproduction And Life Cycle
The mechanism of propagation in Foraminifera organisms varies greatly per species. This has a direct impact on how often the species reproduce annually.
Although procreation is widespread amongst planktonic organisms, few procreate only one or two times in a month (shallow-dwelling organisms), while those at deeper layers procreate once per year.
Adult organisms release up to 200,000 gametes into their environment, increasing the odds of conception by gamete fusion.
After fertilization, a new breed of Foraminifera becomes mature, enabling the process to repeat itself. Provided that the cytoplasm helps to make gametes, fertilization ends the parent’s existence. As a consequence, the empty shell descends to the bottom and becomes part of the ooze.
The life span of benthic species switches between sexual and asexual reproduction. When a mother cell creates microspheric organisms, that is organisms with a small starting chamber, and megalospheric individuals (individuals with a big beginning chamber), the microspheric agamonts divide (asexually) to make megalospheric gamonts, which give birth to biflagellated gametes.
These gametes then combine/fuse to form microspheric agamonts, which multiply asexually.
The protoplasm of the mother cell, like that of planktonic formations, helps to manufacture the gametes associated with the formation of subsequent generations. As a result, the mother cell’s life is cut short, with the empty shell dropping to the bottom of the sea.
Importance Of Foraminifera Species
Foraminifera is significant for a variety of reasons. These are some examples:
- Their skeletons provide information on the complexity of life in their surroundings and also the ages of ocean stones.
- They offer information on their previous habitat, older dispersion, and historic shorelines, among other things.
- They keep a record of climate changes.
- They are employed in oil exploration by determining the age of rock samples in specific geographical locations.
The Bottom Line
As one of the oldest species to be observed and researched in the field of biology, it is without a doubt one that you should know more about, which is why we hope this article has provided you with all the information you need on the Foraminifera species.
These organisms are very interesting to study and do research on, and this article is only a ‘sneak peek’ into their amazing world!
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