Wingworms

Wingworms are a lineage of flying binucleid worms.

Anatomy
Wingworms are unusual among fauna in that their eyes are on their abdomen. Many species fly backwards as a result. Their wings are attached to their cephalic segment. While wingworms ancestrally had many legs, eight on their cephalic segment and two on each abdominal segment, these along with their eyes have been inexplicably lost many times independently.

Descendants of the Twelve-Winged Worm have unidirectional tracheae and semi-active respiration; air enters through tiny spiracles on their face, circulates through the whole body, and exits out near the cloaca. Earlier forms have simpler insect-like tracheae and entirely passive respiration.

The legs of wingworms, when present, are generally soft and unsclerotized, more comparable to the limbs of an annelid or a velvet worm than to those of an insect.

Quite unlike insects, wingworms do not have a larval or nymph stage. Juveniles hatch already winged and can fly once they harden.