INVERTEBRATE ZOOLOGY - H. I. Shcherbak - 2008

KINGDOM MULTICELLULAR ANIMALS (METAZOA)

SUBKINGDOM TRUE METAZOA (EUMETAZOA)

SECTION TRIPLOBLASTIC (TRIPLOBLASTICA) OR BILATERAL (BILATERIA) ANIMALS

SUBSECTION ECDYSOZOA

PHYLUM ARTHROPODA

SUBPHYLUM TRACHEATA

SUPERCLASS HEXAPODA

CLASS INSECTA, OR ECTOGNATHA

SUBCLASS APTERYGOTA, OR THYSANURA

Small insects (up to 1.5 cm in length) with a spindle-shaped body; about 500 modern species are known.

Their winglessness is primary—the ancestors of apterygotes never had wings. Mouthparts are of the chewing type, exposed, and not retracted into the HEAD capsule. They possess elongated spindle-shaped antennae and a pair of compound eyes. The abdomen consists of 11 segments and terminates in three long segmented filaments. Unsegmented paired rudiments of abdominal appendages—stylus—are located on the abdominal segments, supporting the abdomen during locomotion.

Development proceeds via archimetaboly; molting continues even in the adult stage.

The subclass Apterygota includes two orders, with members of the order Zygentoma (Lepismatida) being the most widespread. They inhabit warm, humid places and lead a nocturnal lifestyle; eyes in many species are reduced or entirely absent.

The silverfish (Lepisma saccharina) (Fig. 380, a) lives in human dwellings with high humidity (such as bathrooms). It feeds on mold Fungi, various organic residues in dust, and can consume starch paste from book bindings, occasionally causing damage.

Members of the order Machilida live among rocks and under stones, feeding on Lichens or humus (Fig. 380, b). They are capable of jumping distances up to 15-20 cm.

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Fig. 380. Apterygotes:

a - silverfish Lepisma saccharina (from Gilyarov); b - bristletail Machilis sp. (from Dogiel)