Radiolarian exoskeleton in Differential Interference Contrast (DIC)

This article shows a kind of microscopic sea life called radiolarians under different kinds of magnification:

* Darkfield Illumination
* Differential Interference Contrast (DIC)
* Phase Contrast Illumination
* Rheinberg Illumination
* Hoffman Modulation Contrast

But first, here’s the introduction:

Radiolarians are single-celled protistan marine organisms that distinguish themselves with their unique and intricately detailed glass-like exoskeletons. During their life cycle, radiolarians absorb silicon compounds from their aquatic environment and secrete well-defined geometric networks that comprise a skeleton commonly known as a test. The radiolarian tests are produced in a wide variety of patterns, but most consist of an organized array of spines and holes (pores) that regulate a network of pseudopods useful in gathering food.

The article concludes

The radiolarian exoskeleton, featured in the photomicrographs presented in this section, is encased in the cellular cytoplasm with the bulk of the test being set in the ectoplasm. This anatomical feature ensures that the amorphous silica skeletal structure is never in direct contact with seawater, reducing the risk of dissolution in a hostile aqueous saline environment. When radiolarians die, their tests usually sink and accumulate on the ocean floor in biogenic sediments. Contributing to the pelagic oozes that date back millions of years, the ancient radiolaria skeletons are often useful in geological dating experiments, climatological studies, and oil exploration. The process of biogenic sedimentation, which began with primitive members of the radiolaria during the Early Cambrian period, continues today.


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