acaridarachnid (subclass Acari or Acarida or Acarina)

Main

any member of the subgroup of the arthropod class Arachnida that includes the mites and ticks.

General features » Size range and diversity of structure

Some mites are as small as 0.1 mm (0.0039 inch) in length, while the largest ticks are slightly more than 30 mm (1.18 inches) long. Nymphs and adults generally have four pairs of legs, although newly hatched larvae have only three pairs. Members of some families have a dense covering of stiff hairs, or setae, while others are almost nude. Soft-bodied mites and ticks have only a few hardened plates, or shields, but others are strongly sclerotized with numerous hardened plates covering the body. Acarids range in shape from minute, soft-bodied, elongated or circular individuals to large, hard-bodied, spiderlike ones. Some are flattened, but others assume grotesque body shapes as they become engorged with food or filled with eggs.

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