The main difference between foraminiferans and actinopods is that foraminiferans belong to the phylum Foraminifera and have shells made up of calcium carbonate or sand grains (agglutinate), whereas actinopods belong to the phylum Actinopoda and have siliceous shells.
Foraminiferans and actinopods are two types of living organisms living in aquatic environments. A common characteristic of these two types of organisms is that they possess a shell or tests (internal shells) made of different types of materials. These organisms also possess pseudopodia, which they mostly use for feeding. But, they also use pseudopodia for locomotive purposes.
Key Areas Covered
1. What are Foraminiferans
– Definition, Structure, Characteristics
2. What are Actinopods
– Definition, Structure, Characteristics
3. Difference Between Foraminiferans and Actinopods
– Comparison of Key Differences
What are Foramniniferans
Foraminiferans are single-celled organisms with tests or shells. They belong to the subphylum Ectoreta, phylum Retaria, and kingdom Chromista. They are amoeba-like protists. Foramniniferans most commonly inhabit marine environments. They also live in brackish estuaries, coral reefs, and intertidal salt marshes. The size of an adult individual ranges from 100 micrometers to 20 centimeters. The simplest form of these organisms takes the shape of open tubes or spheres. Once these organisms grow, the shells divide into chambers. The constituent material of the cell can vary from species to species. The shells are composed of crystalline calcium carbonate, organic compounds, sand grains (agglutinate), or other particles cemented together. The tests can be of different types; for example, simple tests, spiral tests, and complex tests.
Some organisms of this species live only a few weeks, while some other organisms live for years. Foraminiferans are food for marine snails, sand dollars, and small fish. Foraminiferans eat foods such as single-celled algae, diatoms, and organic molecules. Additionally, they catch their food by a network of pseudopodia (false foot) arising from shell openings. Some foraminiferans also use pseudopodia for locomotion.
What are Actinopods
Actinopods are a type of free-floating protozoans with highly specialized pseudopodia. They belong to the subphylum Sarcodina, phylum Sarcomastigophora, and kingdom Protista. The class Actinopoda contains two orders: Haliozoa and Radiolaria. They are marine organisms, but they can be found in freshwater too. Like foraminiferans, they have shells.
Most actinopods exist in single-celled solitary form, freely floating in their habitat. Some species are colonial, forming a mass of collective organisms. They also have characteristic pseudopodia. Moreover, they have a siliceous skeleton with perforations in them, which are arranged as spheres. Pseudopodia strengthened with axial filaments project out from these holes. We call this type of pseudopodia axopodia. Axopodia consists of a core of microtubules with a covering of flowing cytoplasm. These microtubules also have cross-like patterns. These patterns vary from one species to another. The food caught by axopodia is brought into the cell body by cytoplasmic movements. It is then ingested by the cell body. Furthermore, the radial arrangement of this axopodia is a significant feature in the identification of these organisms. These organisms use pseudopodia for feeding and locomotion.
The outer cytoplasm also may contain organelles that can be extruded and used in capturing the prey. Moreover, these organisms can quickly retract their axopodia. The re-extension of axopodia is comparatively slower. However, the way in which axopodia move can vary from one species to another.
Difference Between Foraminiferans and Actinopods
Foraminiferans are single-celled organisms with tests or shells, while actinopods are a type of free-floating protozoans with highly specialized pseudopodia.
Foraminiferans belong to the phylum Foraminifera whereas actinopods belong to the phylum Actinopoda.
Foraminiferans have a shell made up of calcium carbonate or sand grains (agglutinate), whereas actinopods have a siliceous shell.
Foraminiferans are larger in size, whereas actinopods are comparatively smaller.
Foraminifera and actinopods are two types of living organisms living in aquatic environments. These organisms possess shells or tests and pseudopodia. The main difference between foraminiferans and actinopods is that foraminiferans belong to the phylum Foraminifera and have shells made up of calcium carbonate or sand grains (agglutinate), whereas actinopods belong to the phylum Actinopoda and have siliceous shells.
1. “Class Actinopoda – Species Examples and Characteristics.” BioTheories.
2. “The World Foraminifera Database.” Marine Species.
1. “Foraminifera – Rotaliida – Planorbulinacea – Planulinidae – Planulina Limbata” By Louis-F. Stahl (CC BY-SA 3.0 de) via Commons Wikimedia
2. “Actinopoda (Optical microscope)” By Altadil – Own work (CC0) via Commons Wikimedia