Archaeognatha (Order: Microcoryphia)

A photograph of a Sea Bristletail (_Petrobius maritimus_).

The Sea Bristletail (Petrobius maritimus) is a common species around the coast of Britain.

This order of insects are superficially very similar in appearance to the Three-pronged bristletails and, originally, they were thought to be part of the same order. However, more recently they have been recognised as a different insect order within the Apterygota. The scientific name for the order - Microcoryphia - comes from the Greek micro (small) and coryphia (head) and they do have rather small heads in front of a large pronotum.

They are elongate wingless insects with a pair of antennae. At the end of the abdomen they have two cerci and a central caudal filament. Unlike the Three-pronged bristletails, the Archaeognathans are able to jump by rapidly bending their abdomens downwards.

Archaeognathans are often found in groups and they feed on algae and other vegetable matter. Eggs are laid singly and the young nymphs are similar in appearance to adults but are smaller.

Entomologists estimate there are roughly 350 species of Archaeognathans worldwide. One of the commonest species in the UK is Petrobius maritimus (sometimes called Jumping Jack or the Sea Bristletail) which can be up to 2cm in (body) length.

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