Solo or social

At times we need privacy and we keep away from others, even from our own people. We meditate, do some creative work, resolve issues, sort out personal problems or just laze around without being bothered by anyone else.

Some other times we actively seek company of friends, family, and go to a great length to be a part of a group of people.

There are some animals that are solo or social. But their being social is very much different from that of ours. Many individuals of their species merge to form one integrated single cohesive creature. They can segregate and aggregate that is become one big multicellular body or break up into individual cells almost at will. Amazing, isn't it? See for yourself the slime molds - http://www.ucmp.berkeley.edu/protista/sl... and http://www.nih.gov/science/models/d_disc... And follow their life cycle on - http://www.ruf.rice.edu/~evolve/Lifecycl... I am talking about the slime molds or the social amoebae like the Dictyostelium discoideum. The slime molds were classified as fungi at one time. But now they are considered as members of protista, a kingdom consisting of small organisms with distinct nuclei. Many of the slime molds or the social amoebae are creatures that spend a major part of their life as the unicellular protozoa. They move on soil with pseudopodia and feed on bacteria. When food is hard to get, they aggregate. They form a multicellular organism. Amoebae like the Dictyostelium discoideum when in multicellular form appear like slugs and are mobile. The slug is bullet shaped and is up to two millimeters in size, that is it can visible with naked eyes. Such a slug may be an aggregate of up to 500000 cells A slug develops two parts in its body. A stalk and a capsule like hollow sporangium. The sporangium is the fruiting body which produces spores like the fungi do. The sporangium holds and protects the spores for some time. Ultimately the spores are released into dry weather. On dispersal they may grow into single cells of the amoeba. The cells that develop into sporangia get an opportunity to become spores and perpetuate the race. The cells that grow into a stalk sacrifice their reproductive potential and only support the sporangium. Stalk cells do not get to make any genetic contribution to the next generation. These apparently weird creatures are of great interest to biologists for several reasons like - it is possible to learn how cells interact, how cells initially similar in structure differentiate and specialize, which chemicals act as signals and what motivates some cells to become stalk cells and sacrifice their potential to pass on their genes to their progeny.

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