Classification of Organisms

Artificial, Natural, phylogenetic are main Classification of Organisms,

An Artificial classification is based on one or many easily observed similarities and feature. For example, Linnaeus included all worm-like organisms in a single group, the Vermes. This was called as  artificial classification because it did not indicated the relationship that various animals have with each other like that  birds have with snakes, in possessing a vertebral column whereas nematodes and earthworms do not have a vertebral column though included in the same group. Similarly, bacteria, fungi, protozoa which are are known as microorganisms form a convenient group for the purpose of study but not a natural group.

A Natural classification uses natural relationships and similarities between organisms. Most classification in use today is natural and phylogenetic. A phylogenetic system classifies organism on the basis of its evolutionary existence, which also reflects its genetic information. Phylogeny refers to the history about the evolution of species.

  Schistosomiasis is an infection in blood caused due to a flatworm which is parasitic in nature called as Schistostoma . During part of its life cycle, the worm inhabits freshwater snail. People become infected when larval Schistostoma swim from a snail and penetrate their skin in paddy fields. The worms live in person's abdominal blood vessels and cause a slow death.

          Till 1970s, only one species Schlstosoma japonicum was known to infect humans and was thought to be transmitted by a single species of snail of the genus Oncomelania. After extensive field surveys, anatomical, genetic and geographic research on worms and snails of Southeast Asia, it was discovered that a different snail was transmitting Schistostoma to human beings in Laos. It was also found that S. japonicum was actually a cluster of at least six species and that evolutionary relationship among snails determined which species could host Schistostoma. Evolutionary diversification from an ancestral stock of snail had produced a group of species of modern snail. Of these only three retain the ability to host Schistostoma, and ten have a genetic trait that, makes them unsuitable hosts for the disease. The above mentioned information is a good example of using methods of modern SYSTEMATICS to combat Schistosomiasis. Most of the species of freshwater snails in Southeast Asia have not been described and named. By using information one evolutionary relationship among snails, scientists can quickly determine whether or not a newly found snail is a host for Schistostoma. Then control efforts need to be

Directed towards only the snails that can transmit Schistostoma to human beings and not to all freshwater snails in the region.

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