Read our copyright notice Actinocyclus sp. Chain Diatom Illustrated here are two different kinds of diatom, class Diatomeae, phylum Chrysophyta. These organisms belong to the plant Kingdom. Both of these are planktonic, marine specimens. These specimens were mounted upon a victorian microscope slide.
Diatoms are unicellular organisms that lack a flagellum.
They range from 0.0015 to 2 mm in size and their siliciceous tests may be cylindrical, elliptical, polygonal or lancet shape, some forming long chain-like colonies. Diatoms inhabit both freshwater and marine environments and belong to both the planktonic and benthic communities. Some planktonic forms can regulate their buoyancy, and many benthic species are able to crawl slowly over the substrate. It is thought that some diatoms secrete a mucus-like substance that aids their locomotion. Though the majority of diatoms are free-living and autotrophic, some are symbionts or parasites upon, for example, foraminifera , corals and algae.