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10 new species of freshwater earthworms discovered

Last Updated: Thursday, February 7, 2013 - 19:44

Bangkok: Scientists have discovered an astonishing 10 new species of semi-aquatic freshwater earthworms in river systems in Thailand.

According to a report published in the journal ZooKeys, the earthworms in the genus Glyphidrilus occur in a wide range of natural freshwater habitats, including rice fields, where they might play an important role in the development of organic farming.

The newly-discovered worms have a rounded body tip, while the end is square shaped. When twisted, the posterior end, which is normally above the soil surface, forms U-shaped channels. These are used to allow water circulation down the burrow.

This is probably an evolutionary adjustments that ensures oxygen transport to the deeper surface of the worms, while their bodies remain in the burrows.

Another peculiar feature are the so-called "wings", or the expanded part of epidermis near the body tip. The function of the wings is still unknown to scientists, but it has been suggested that they evolved to assist breathing in such aquatic habitats.

Since the wings will be located deep in the burrow at a low oxygen supply and are absent in sexually immature juveniles, a more conventional explanation might be that they are used to aid copulation rather than respiration.

The worms turn out to play an important role in the development of rice farming, being a facilitator in the decomposition of organic matter to be a natural fertiliser, as well as improving the soil properties for better rice root system.

The species also assist the release of essential minerals in some chemical fertilisers, though not in pesticides, which prove to be lethal to the worms.

"The worms will survive in areas using chemical fertilisers but not those using chemical pesticides," said the author of the report, Dr Somsak Panha, from the Animal Systematics Research Unit, Chulalongkorn University in Bangkok, Thailand.

"However, the worms did well in areas of organic farming and so are likely to be sensitive to modern agrochemical contamination of the environment. They may play an important role in organic rice farming," he said in a statement.


First Published: Thursday, February 7, 2013 - 19:44
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