Moss Balls or marimo (Japanese for "ball seaweed"), also known by various names such as Cladophora ball and Lake ball, is a species of filamentous green algae named Aegagropila linnaei that grow into large green balls with a velvety appearance. These balls grow to sizes of 12 to 30 cm across, depending on where you find them. Marimos are rare and is known to occur only in Iceland, Scotland and Japan, primarily Lake Akan in Japan and Lake Mývatn in Iceland. Recently, moss balls appeared in a large numbers on Dee Why Beach, in Sydney, the first such spotting of this algae in the southern hemisphere.
Marimo doesn’t grow around a core, such as a pebble. Instead, the algal filaments grow in all directions from the centre of the ball, continuously branching and thereby laying the foundation for the spherical form. Surprisingly, the ball is green all through, although light only reaches very short distance into the ball. The chlorophyll inside the ball remains dormant in the dark, but becomes active when exposed to light if the ball breaks apart. Moss balls are found submerged in the lake’s bed where the gentle wave action frequently turns them over maintaining its spherical shape, at the same time ensuring that they can photosynthesize no matter which side is turned upwards.
Marimo in a tank in Hokkaido, Japan. Photo creditRead more »
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