Euglena.

This alga can be found in almost any location that you care to visit where there is fresh or brackish water. It thrives best where there is an abundance of rich organic waste. There are between 800-1000 different species of Euglena within the British Isles. The shape of the Euglena can change very quickly enabling it to move around and through other wise impenetrable obstacles. It moves with the aid of a single flagellum that emanates from a very small depression called the reservoir, a much smaller flagellum is also present but I have been unable to locate this with any of the specimens that I have caught. According to Alan Pentecost in his book called an Introduction To The Freshwater Algae the small flagellum acts as a light receptor.Euglena also finds it's way to light and dark areas by using the light detector called the stigma that is located on the anterior end of the alga. There are some species of Euglena that are bright red in color ( E.sanguinea ) and this is due to the pigment called astaxanthin, this pigment can also found in Haematococcus. There method of reproduction is asexual and this is carried out by splitting longitudinally, it is not certain whether these microbes reproduce by sexual means. Euglena can live as an autotroph or mesotroph when placed in darkness for any length of time but when re introduced to light will regain its chlorophyl.

The duck pond in the village of Fring.

 
This small duck pond in Fring in North Norfolk was covered with Euglena. It is amazing to think how many individuals there are in this bloom. Norfolk is an excellent place to take your microscope because of the huge amount of waterways that are available.

 

 
 Fig 1a.This bright field photograph shows hundreds of Euglena in one small drop of water.The container, which held about 500mls was green on top down to a few millimeters deep.These blooms can occur fairly rapidly and disappear just as quick.

 

 
 Fig 1b. This is a darkfield view of the same mass of Euglena but with a slightly higher magnification.

 

 
 Fig 2. This photograph shows how easily the Euglena can alter its shape when it meets an obstacle.

 
 Fig 3. A photograph of Euglena taken with a X40 Nomarski interference objective.The bar is about 50um. The single flagellum can just be seen along with the many colorless paramylum bodies that are found within the cell body.

 
 Fig 4.This is the palmelloid stage of development where the Euglena rounds up into a ball discarding its flagellum. They will stay in this stage until their environment improves. Note the red eye spot on the far left specimen. The bar is about 40um.The photograph was taken with a DIC objective.

 
 Fig5. This phase contrast photograph shows the mucilage that has been secreted by this Euglena. Euglena can divide while embedded in the mucilage coat and will rapidly spread out. When looking at the mucilage there appeared to be what looked like hundreds of bacteria that have become embedded within this mucilage coat. X40 phase contrast objective.

 
 
Figs 7.These photographs show the Euglena dividing into two separate organisms by splitting down the middle. Binary fission usually begins with the on set of night fall with the large flagellum being shed first. The nucleus, chloroplast and basal bodies all divide so each new cell ends up with the required cell components. This procedure takes quite a long time and requires plenty of spare time to follow all the way through. The paramylum body and also the stigma can be seen in photograph (a). Photographs b, c and d show how the cell begins its division at the anterior end and slowly works down until separation is completed with the aid of two new flagella that also form during this process.

 


Introduction to photomicrography.