Dragonfly
Reference: Compound eye
The one creature in this catalogue that genuinely has six limbs and wings at the same time — because it is not a vertebrate, and its wings were never limbs to begin with.
Scored on every axis
Why the insect gets away with it
Insects keep all six legs and carry wings, because insect wings are separate structures rather than converted forelimbs. Their evolutionary origin is still argued, with current evidence favouring a dual origin drawing on both body wall and leg base.
So “legs plus wings” is not impossible in general — it is impossible in a vertebrate, which is the precise form of the four-limb constraint. A dragon with four legs and two wings is not built like a dragonfly; it is built like a horse with wings bolted on, and no vertebrate has ever been built that way.
Thirty thousand small eyes, and no lungs
Each compound eye carries on the order of 30,000 facets, giving near-spherical coverage and outstanding motion detection at low spatial resolution — the opposite trade from the eagle. Dragonflies intercept prey on a predicted course rather than chasing it, and succeed on most attempts.
There are no lungs and no oxygen-carrying blood. Air enters through openings along the body and travels to the tissues by tube. This works well and sets a hard ceiling on size — when atmospheric oxygen was much higher, dragonfly relatives reached wingspans near seventy centimetres, and they have never been that large since.