Key to the Main Groups

Without legs
With three pairs of legs. Often with wings insects
N.B. Newly hatched mites also have three pairs of legs, but they are extremely small, under 1 mm.

With four pairs of legs spiders, mites, scorpions etc.
With more than four pairs of legs.

It may be a slug slugs

It may be a worm worms.

It may be a maggot-like insect larva insect larvae.
With three pairs of true legs, and prolegs on abdomen certain insect larvae.

With 7 pairs of legs woodlice.
With many legs, more than 14 pairs

Flat animals, legs protruding laterally centipedes.

Cylindrical animals, legs attached ventrally millipedes.