Zandvlei Trust

Macro and Mycroscopic predators (Extract article from the volume 2006/1 Newsletter)

Where do food chains and webs really start? 
After the final decomposers and nutrient recyclers have done their work. The truth is, there is no begining and no end. It is a continuous cycle, but it definitely begins beyond the visible. Nearly all members of the lower orders of life require water or extremely damp conditions to survive and do their work. Many of these lower orders of life produce eggs or spores or become cysts and, being very light, are picked up in the air currents and winds and circulated around the world and if they land in a suitable habitat, they thrive. If you boil grass very well until it is reduced to a nutrient soup and put it outside, within a couple of days it will be full of life of increasing variety.

However, life at this level is complete anarchy. These are endless and continuous battles for survival where bullying, cannibalism, incest, infanticide, intimidation, murder, malnutrition, predation, protection payments, rape, robbery, starvation, theft and violence are a normal part of life; where every emergence from hiding constitutes visibility coupled with terror and trepidation.

Reflect on how lucky we are to belong to a life form which has few natural enemies and have customs and laws to protect us, schools to educate and guide us, and medical facilities to look after us.

Meet some of the most vicious macroscopic predators;

Larvae of crab and freshwater crabs,

The larvae of dragon and damsel flies, capable of jet propulsion with a grasping mask,

The larvae of beetles, efficent and violent killers in wetlands.

Cyclops and Daphnia. Of particular interest to the people of the southern suburbs as they cause concern in Janaury and February due to their ability when oxygen is in short supply, to produce hemoglobin as a survival technique, which acts towards oxygen as a magnet to iron filings. This colours the outfall from Strandfontein with billions of daphnia the colour of blood being flushed out. They are flushed out all year round but when oxygen is readily available due to a reduced demand, they are a grey green colour, which matches the colour of the sea water and as a result are not noticed.

At microscopic level we have many predators. In fact everyone is somebody else's food source. There are ciliates and flagellates of many different kinds.

At microscopic level even plants leap about (or to be more scientific, motile), such as some green algae, eugenoids, etc.

Beginners to natural history are in a very fortunate position. They are interested in a subject in which more has yet to be discovered than is already known.

No matter what age you are, you could very easily discover new things about the behaviour, breeding, distribution and feeding habits of many species and life forms.

You can make a contribution, and at the same time develop a consuming hobby. Natural history is a great leveler. If you study and learn interesting facts about natural history, you can hold the interest of the high and mighty, including kings and presidents.

Frank Wygold


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