Geoscience Reference
In-Depth Information
ern classification and nomenclature, may therefore be forgiven, perhaps, for turning a
blind eye to their diversity and treating them all as a single genus
Acarus.
A century
later, in the 1830s, C.L.Koch published his monumental work on the group. This was
not only a major reference source but the terror of subsequent acarologists, for he col-
lected assiduously and drew and named every specimen with scant regard to whether
it was just a different sex or an immature form of something already described. We
owe a great debt, therefore, to later British pioneers who established the basis of our
acarine fauna: to men like A.D.Michael in the 1880s and J.E.Hull, J.N.Halbert and
F.A.Turk in the first half of this century.
Mites are related to spiders, harvestmen, false scorpions (
Plate 6
) and several
mainly tropical groups (such as true scorpions) within the class Arachnida. Whereas
all these other orders are entirely predatory, mites include many groups which feed on
living or dead plant material, bacteria and spores. The diversity of form among free-
living soil mites is enormous. Indeed the only obvious features they have in common
are their four pairs of legs (in the nymphal and adult stages), and an unsegmented
body; and even this may be partially divided in some groups. Eyes are generally lack-
ing but one or two pairs of simple eyes may be present.
F
IG. 19
Stereoscan photograph of an oribatid mite
Nothrus silvestris.
(Cryptostigmata). (National Museum of
Wales.)
The most abundant group of mites in moss, leaf litter and soil are the Cryptostig-
mata, so called because their breathing pores (stigmata) are inconspicuous. These are
