Six Continents of the Eternal Life

E. I. Loseva, R. Crawford, M. Poulin, N. B. Balashova

Diatoms live either as single cells or unite in colonies of intricate shapes of chains, tubes, stars, fans, ribbons, pellicles… Being able to live in almost any aqueous medium, diatoms are ubiquitous and can be found all over the world, from the poles to the equator. They propagate quite fast, and rates of fission vary for different species and depend on the environmental factors, such as geographic latitude, season, lighting, temperature and nutrients content.

Some diatoms, which are inhabitants of the ocean floor (the so called benthic species), are able to move on a solid substratum such as the surface of an animal. Diatoms of another kind (benthic) fasten onto various surfaces: bottom of a water body, plants or even onto ship bottoms. Certain species live on one and only certain substratum (for example, on the bodies of Antarctic whales). Planktonic diatoms can float freely in the water due to multiple inclusions of oil drops and thin porous shell. Dead cells lose this ability and sink.

The composition of diatom communities depends on ecological factors of the environment and varies through seasons.

The diatoms require many diverse chemical elements for their normal growth and reproduction. They cannot do without silicon, which constitutes their shells and which eventually limits their quantitative growth. Diatoms with rough shells consume much more silicon than thin-shelled ones, and when silica is abundant in the surrounding environment, shells are noted for very thick walls. Silicon consumption is the largest in the propagation season; as a result the silicon content in the water falls sharply and is restored only later due to its inflow from the basin's depth. That is why even artificial addition of silica to the water causes a short sharp increase of diatom population

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