Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 25

Microorganisms are (mostly) life-forms too small to see with the naked eye. Many of these are smaller than the cells that make up our bodies, but what they lack in size, they more than make up for in numbers. The ocean is home to an estimated 44 octillion microbes — more than all the stars in the known universe. Perhaps more amazing is that microbes comprise somewhere between 90 and 98 percent of the marine biomass (the total mass of all marine life)! These microorganisms can be broken down into four groups:

 Viruses are infectious agents that invade cells and use them to replicate. They’re not even classified as living beings (burn!).

 Bacteria are single-celled organisms that have a cell wall but no nucleus (a container for most of the cell’s genetic material) or organelles (specialized structures in a cell that perform various functions).

 Protists are single-celled organisms equipped with a nucleus and organelles. They’re not animals, plants, or fungi, but some are similar to plants in that they perform photosynthesis, some are similar to animals in that they move around and eat stuff, and some are more of a cross between the two — moving around, eating stuff, and performing photosynthesis.

 Fungi are single-celled or multicelled organisms that feed on organic matter. They include yeasts, molds, mushrooms, and toadstools.

Microorganisms are a vital component of oceans. They serve as producers, making food for consumers at the bottom of food chains, and they serve as decomposers, breaking down animal waste into chemicals that can be reused. See Chapter 7 for more about microbes and the important roles they play.