Healy and Rota 1992

Healy B, Rota E. 1992. Methods for collecting Enchytraeidae during expeditions. Soil Biology and Biochemistry 24: 1279-1281.

These authors succinctly describe methods for collecting, extracting from soil and other materials, sorting, maintaining alive, and fixing and preserving enchytraeid worms. Enchytraeids are found in all moist soils, and other materials such as tide debris and forest litter. In this study, 0.5 kg soil samples were kept in plastic bags for up to five weeks before extraction of worms.

The methods described here were developed during an expedition by the authors to north Africa; Ireland, their home, does not allow import of soil samples so they were forced to extract worms in the field. The basic extraction method is a modification of O’Connor’s (1957) “wet funnel”, which is much more clearly described and illustrated here than in that older work. Figure 1. of this paper shows a wet funnel. Worms move down away from the source of light and heat (a light bulb) into a funnel full of water connected to a bottle. After an undescribed period, probably at least three hours, the water in the bottle is dumped to Petri dishes and worms sorted. The authors describe sorting using the naked eye, but recommend a magnifying glass with attached light source for smaller specimens. Living enchytraeids can be maintained in culture with soil agar, made from 2% agar and a 1:1 mixture of soil and distilled water. Soil and debris added with the worms will ruin sterility, but provides food for the worms. Water should be added periodically to keep everything moist, about every five days. Worms in this study were narcotized with soda water, and the authors describe dilute beer as an acceptable substitute. Fixation and preservation can use “any of the usual fixatives”, though contraction of specimens can make it difficult to distinguish taxonomically-important internal organs.