Fish
Flying Gurnard
Dactylopterus volitans · also called flying gurnard, helmet gurnard, butterfly gurnard
The flying gurnard has the most theatrical fins in the shallows — vast rounded fans spotted in peacock blue that it snaps open to twice its size when startled. It cannot fly, or even glide. It spends its life trudging across the sand on the finger-like rays of those same fins, feeling for crabs.
Overview
Flying gurnards live on sand, mud, and seagrass in warm parts of the Atlantic and the Mediterranean, in shallow coastal water. They grow to about 50 cm, with a blunt armoured helmet head, a plated body, and hugely enlarged pectoral fins edged and spotted with bright blue. They eat crabs, shrimp, clams, and small fish.
The “wings”
The wing-like fins are normally folded flat. The fish spreads them suddenly when alarmed or displaying, flashing the blue to look bigger and startle a predator. It cannot leave the water and does not glide — the name is purely for the fins’ shape.
Walking on fingers
The front rays of each pectoral fin are separate and finger-like. The gurnard moves them one by one to clamber across the bottom and uses them as feelers and rakes to find and flush buried prey.
Not a true gurnard
Despite the name it is not closely related to the true gurnards (sea robins); it is the sole Atlantic member of its own family, and the resemblance is convergent evolution.
Status
The flying gurnard is Least Concern, widespread and reasonably common, of minor fishery interest and no significant conservation concern.
Flying Gurnard: common questions
Can the flying gurnard actually fly?
No. Unlike the true flying fish, which build up speed underwater and genuinely glide above the surface on stiff pectoral fins, the flying gurnard stays on or near the bottom and cannot leave the water. Its huge, wing-shaped pectoral fins are normally held folded against the body, and it spreads them for two reasons — as a threat and startle display, suddenly opening them to appear much larger and to flash the vivid blue spots and margins at an approaching predator, and possibly in courtship. Juveniles may spread the fins while making brief swimming hops off the bottom, which can look like an attempt at flight, but there is no gliding. The name comes purely from the wing-like appearance of the fins.
How does the flying gurnard "walk" and find food?
The first six or so rays of each large pectoral fin are separate from the rest of the fin and are stiff, mobile, and finger-like. The flying gurnard rests these on the seabed and moves them one after another to prop, push, and clamber slowly across the sand, so it appears to walk on its fins. It also uses them as feelers and rakes, prodding and sweeping the sediment to detect and dislodge buried crabs, shrimp, small clams, and fish, which it then snaps up. True gurnards (sea robins) have the same adaptation, which is one reason the two unrelated fish look and behave so alike.
What is the difference between a flying gurnard and a sea robin?
They look similar and share the "walking on finger-fins" habit, but they are only distantly related. Sea robins (family Triglidae, the true gurnards) have large but less dramatically rounded pectoral fins, usually with three fully separate finger rays on each side, a more sloping head, and they are common food fish in many regions. The flying gurnard (family Dactylopteridae) has much larger, broader, more colourful fan-like pectoral fins, a very blunt bony helmet of a head, a long spine projecting back from the head, and six or more finger rays per side. The resemblance is convergent evolution — both evolved bottom-walking fins and expanded pectorals for a similar life on soft sea floors.
Is the flying gurnard good to eat or keep in an aquarium?
It is edible and is landed in small quantities as bycatch and by artisanal fisheries in parts of its range, but it has little commercial value and is not a targeted species. In the marine aquarium trade it is occasionally offered as an oddity for its dramatic fins and bottom-walking behaviour, but it is considered a poor choice for most keepers — it needs a large tank with a deep, open sand bed and plenty of live and meaty foods, it is slow and easily outcompeted by faster tankmates, and it often refuses to feed and slowly starves in captivity. Experienced keepers with a species-appropriate setup have kept it, but its wild-collected origin and delicate feeding make it best left in the sea.