Microcystis.

A Cyanophyte.

The above photographs show some of the amazing shapes that this Cyanophyte can create.

The Cyanophytes have possibly been around in one shape or another for 3.5 billion years and were the dominant life form for over a billion years. Scientists now have good evidence to suggest that these single celled organisms were the first oxygen producers on the Earth and the fossilised remains of Cyanophytes have been discovered in structures called stromatolites that are 2.7 billion years old. Obviously no one can be certain about the dates because of the enormous spans of time, these figures mean nothing to the lay person nor to the scientists who figures them out. However, they do give some idea of how ancient the Earth is and how long life has been established on this planet.

Microcystis is found in lakes and ponds and as can be seen from the photographs can grow into some weird and wonderful shapes. The colony is held together by mucilage and consists of thousands of individual cells, which are about 2-3 µm in size. When the spring arrives large numbers can sometimes be seen floating on the top of the water giving a bluish tinge to the surface. However, when viewed through the microscope the cells appear black, which can be seen in Fig 1. The cause of this black colouration is due to the gas vacuoles that are located within these cells, which by the way cannot be seen through the light microscope. The gas vacuoles may possibly allow the colony to drift through the water layers to find the right amount of sunlight energy. Looking through the book called Freshwater Algae by Carter & Lund there are some fine examples of how this Cyanophyte can take up remarkable shapes. A down side to this Cyanophyte is the deadly toxin that it produces when waterblooms of this organism take over the lake or pond, killing fish and live stock in great numbers.

Introduction to photomicrography.