Rev 05/06/24
Body Mass of nematodes may be calculated using the Andrássy (1956) formula W = (L*D2)/(1.6*106) where W is the mass (as fresh weight μg) per individual, L is the nematode length (μm) and D is the greatest body diameter (μm).
The formula is based on the generally elongate and cylindrical morphology of nematodes, tapering towards both ends with the anterior bluntly rounded and the posterior more acute.
Andrássy (1956) derived the formula by first calculating nematode volume and then determining nematode density (S) as the specific gravity of liquids in which they neither rose nor sank. Then, W = SV.
Nematode volume
was determined initially as the sum of the volumes of a series of complete and
truncated cones. Since the method was measurement-intensive, Andrássy sought
proxies and determined that, for nematodes of different sizes, a formula for
volume based on body diameter and length (V = (L*D2)/1.7, where1.7 is
an empirically-determined constant, provided a volume estimate within 2% of that
determined by the more intensive calculation.
I calculated volumes and body weights per Andrássy (1956) for 8,533 records of nematode species (males and females) based on data readily available in the literature. Since ecosystem functions and services are often reported at the family or genus level, I determined average weight for the species (ased on females) in each family (170 families) or genus (773 genera). Note that family assignments of nematode general differ among authorities, which may have considerable effect on the average weights and their standard deviations. I provide family assignments for each species according to several authorities.
Andrássy I (1956) Die rauminhalst and gewichtsbestimmung der fadenwurmer (Nematoden).
Acta Zoologica Academi Sciences,
Freckman. D.W. (1982) Parameters of the nematode
contribution to ecosystems. Pp 81-97 in Freckman, D.W. (ed) Nematodes in Soil
Ecosystems.