Plankton by the ton

After last week’s largest living thing, this week we look at some tiny but very important organisms.

Plankton are an essential part of the marine ecosystem. They include microscopic life forms such as diatoms and coccolithophorids, although they’re not limited to the very small. Even animals as large as jellyfish can be considered plankton: the word plankton comes from the Greek planktos, meaning “to drift”, so any living thing that drifts in the ocean counts.

Scanning electron micrograph of the coccolithophore, Gephyrocapsa oceanica (click to embiggen)
Scanning electron micrograph of a coccolithophore (Photo by NEON ja, colored by Richard Bartz, via Wikimedia Commons)
However, it’s the tiny, photosynthetic organisms known as phytoplankton that are crucial in removing carbon dioxide from the atmosphere, and could potentially help combat global warming. But even though they produce more oxygen than all plants on dry land, phytoplankton are also threatened by changes to climate.

The good news is that some recent research has shown that iron helps phytoplankton to grow, particularly iron produced naturally in sperm whale poo (Lavery TJ, Roudnew B, Gill P, Seymour J, Seuront L, Johnson G, Mitchell JG & Smetacek V 2010, “Iron defecation by sperm whales stimulates carbon export in the Southern Ocean”, Proceedings of the Royal Society B, vol. 277, no. 1699, pp. 3527-31). Another good reason to save the whales!

For more on plankton, see Beyond the Reef at the Australian Museum, or the Monterey Bay Aquarium Research Institute. Or if you want to read more about whale poo, read the full story at ABC Science.

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