![]() ![]() ![]() Unpigmented species which are semi-transparent often have a pale pink colour which is due to haemoglobin in the blood this colour disappears very rapidly when the animal is preserved. Pigmented species are usually darker in colour dorsally than ventrally- they may often be white and unpigmented ventrally, but pigmented dorsally. Some worms are pigmented and the body wall is opaque, while others are unpigmented and may be white and opaque or the body wall may be quite transparent and the blood vessels, intestine, etc., may be readily visible. Only the colour of living specimens is reliable as the common preservatives and fixatives rapidly remove most of the colour. ![]() page 15Ĭolour: Colour is often useful in identification. However, taken in association with other characters it is often useful, and it can occasionally be the principal means of distinguishing species which differ greatly in size. Size: Within a species, considerable size variation is common, so size is not always a useful character for identifying species. The clitellum is usually much closer to the anterior end than to the posterior end. Anterior segments are in general much larger than posterior segments there is also much variation in size from one segment to the next anteriorly, while posterior segments tend to be small and of rather regular size (see Figs. At the front or head end, there is the prostomium (this is a small fleshy lobe which projects forward above the mouth it is described and figured below). Orientation: Earthworms usually move forwards, but they also move backwards, so the identity of front and rear is not always apparent from the direction of movement. Identifications can only be made with certainty on sexually mature specimens, i.e. The remainder of the characters listed are more easily observed on dead than on living specimens. Colour can only be relied upon for living specimens, and should be noted first when examining an earthworm. The anatomical characters described below are those that have been used in the key for the identification of species. ![]() Some Notes on the Anatomy of New Zealand Earthworms ![]()
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