Number of worms

Land, J. van der Land at naturalis.nnm.nl
Thu Oct 22 04:01:23 EST 1998


	On October 14 Mary Appelhof wrote:

	""Of more than 8,700 species of segmented worms that live in our
world, over 4,400 are different species of earthworms."  Is  the 8.700
number in the ball park? Can someone give me a better number?  Would
appreciate your help."

	In an earlier reaction I estimated the number of valid species of
annelids to be in the order of 11.000 of which 3000 are oligochaetes. In
John Reynolds & David Cook's Nomenclatura Oligochaetologica (Supplement 3,
1992) the number of given species names is 7254. Because more than half of
those must be synonyms the number of 3000 valid species is not too low. Of
those at least 600 are microdriles, mostly aquatic. Consequently the
number of known earthworm species is lower than 2400, probably
considerably lower but good revisions are lacking for several groups.

	People tend to think that such numbers are underestimates. That partly
explains the large figures given in many recent publications on
biodiversity (althoiugh they are partly due to estimates of undescribed
species, e.g. in such groups as the nematodes). However, the numbers
circulating in the litterature may be overestimates as well. A good
example is the phylum Sipunculida. I estimated the number of species to be
about 320, but after Ed Cutler's 1994 critical revision only 149 were
left.


Dr Jacob van der Land
National Museum of Natural History - Naturalis
P.O.Box 9517
2300 RA  Leiden
the Netherlands
tel. +31 - 71 - 5687654
fax +31 - 71 - 5687666
e-mail: land at naturalis.nnm.nl

editor of Unesco-IOC Register of Marine Organisms:
http://wwweti.eti.uva.nl/database/urmo/default.shtml

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