Amazing facts!

10 things you didn't know about ....


Plankton account for some of the smallest living creatures on Earth,
and yet without them the food chain would collapse...

Did you know that the name 'plankton' comes from the Greek word 'planktos' meaning wandering or drifting? Most plankton have little or no swimming ability and so they rely on the ocean currents and tides for transport.

Plankton can be plants or animals. Planktonic plants (known as phytoplankton) create energy by photosynthesis, just like land plants. Planktonic animals (known as zooplankton) feed on phytoplankton (herbiovorous) or on other zooplankton (carnivorous), just like land animals.

Planktonic organisms range in size from miniscule microbes, invisible to the naked eye, to giant jellyfish several metres long. The Lion's Mane jellyfish (shown left) can reach up to 3 metres across and over 30 metres long from end to end! Apart from bacteria, planktonic organisms are the most abundant life form on earth.
The weight of all the plankton in the oceans is greater than that of all the dolphins, fish and whales put together. Amazing when you think that many plankton are microscopic in size!

In certain areas, environmental conditions can cause an individual species of plankton to reproduce prolifically, forming a plankton bloom. Some plankton blooms are so large they can be photographed by satellites in space. The bloom (turquoise area) shown in the photograph to the left occurred on the coast of Norway in July this year. You can see how the ocean currents have affected the bloom, creating swirled patterns in the water as the plankton disperses. Certain types of plankton produce red-coloured blooms, which have become known as 'red tides'.

[Click on the image to enlarge]

Some of the types of plankton which form red tides produce the most potent nerve poison known to man. Depending on the species, the plankton can cause paralysis or trick all the nerves into constantly firing. Other plankton blooms can cause people to lose their memory!
Some plankton blooms can pose serious health risks for humans and marine wildlife. Fish living in bloom-affected areas eat the poisonous plankton, which is then passed down the food chain to larger fish and eventually to humans. Cultures which consume seafood as a staple part of their diet (eg, Japan) are particularly at risk. In Cape Cod Bay in 1987, toxic plankton in the food chain caused the death of 14 humpback whales. However, only a few dozen of the thousands of phyoplankton species are known to be toxic.

Approximately 40% of photosynthesis on Earth is carried out by planktonic organisms. That means that nearly half of the world’s oxygen is generated by phytoplankton!

The famous White Cliffs of Dover on the south coast of the UK (pictured left) are made up of millions and millions of fossilised remains of coccoliths, which are a type of plankton. When the coccoliths die, they sink to the bottom of the sea, where their calcium carbonate skeletons accumulate in thick layers to make up chalk deposits.

Right: Photograph of a coccolith skeleton
taken at very high magnification by
a scanning electron microscope.

If size is taken into consideration, the copepod (a type of plankton - pictured right) is the fastest animal on the planet. If it were the size of a cheetah it would be able to run at 2,000 miles per hour (3,218 kilometres/hour). Copepods are also said to be the richest source of protein in the ocean.

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February 2007