bentfin devil ray images in the
Shark Pictures Database
Bentfin devil ray, Smoothtail mobula, Thurston's
Anterior margin of pectoral fins have a double bend.
Dorsum dark grey/blue with black band across shoulders. Wing tips relatively
broad. Dorsal fin has a white tip. Tail spines absent. Ventrum white
with two black patches. Head extension relatively short. Underslung
mouth. Tail length (when intact) about 60% of disc width.
Maximum disc width 1.8m. Disc width at birth 63cm.
Most common in inshore waters from the surface to
100m or more.
Abundance and distribution:
also reported from the
Indonesia, and the
Usually seen free
swimming singly or in small groups. Leaps clear of the water
sometimes somersaulting. Feeds on planktonic organisms. May rest at
surface with wingtips protruding or rest on bottom.
Mating in the
occurs in spring.
Conservation Status: The bentfin
devil ray is listed as 'NEAR THREATENED' globally and 'VULNERABLE' in South East
Asia by the IUCN. Mobula thurstoni is highly susceptible to gillnets and is
known to be landed in Indonesia, México and the Philippines and likely elsewhere
across its range. It is a component of the inshore pelagic tuna gillnet fishery
in Indonesia where the flesh and gill rakers are utilised. The high value of
gill rakers, which are dried and exported for the Asian medicinal market has
resulted in recent dramatic increases in fishing for mobulids in Indonesia with
targeting now occurring. In the Gulf of California, México, the species is
landed in directed artisanal elasmobranch fisheries and as bycatch. In the
Philippines the species was historically targeted in a mixed mobulid fishery,
and while a ban on fishing for devil rays is presently in place, enforcement is
insufficient and landings still occur. Information on catches is not available
from other parts of its range, but it is likely being captured elsewhere,
certainly in Southeast Asia where target fisheries for whale sharks and manta
rays operate. While little species composition data is available, limiting the
assessment of current fishing pressures on populations, increased targeting and
catches in Indonesia, which may mirror increases elsewhere, is cause for great
concern and requires urgent international conservation measures as the species
is unlikely to be able to tolerate present levels of exploitation. Its large
size (to 180 cm disc width) and fecundity of a single pup per litter emphasizes
the limited reproductive potential and low productivity of this species. Mobula
thurstoni is assessed as Near Threatened globally, but Vulnerable throughout
Southeast Asia where catches and demand are increasing. Vulnerable listings may
also be warranted elsewhere if future studies show declines in populations where
Isla San Si Puedes,
Midriff Islands, Baja.
Japanese devil ray
Very similar but with straight anterior margin on pectoral fins and
no obvious markings on ventral surface.
Straight anterior margin of pectoral fins and a more purplish
colouration on the dorsal surface. Sicklefin devil ray
Straight anterior margin of pectoral fins. No white
spot on tail.
Like most devil rays, the Bentfin Devil ray
is difficult to approach unless it is preoccupied with feeding. Moves
away when pursued.
is a sporadically seen mobula ray but it is reasonably common in the Sea of
Cortez at least as far north as the Midriff Islands. Divers should
liveaboard dive trip to the
Midriff Islands to see this species. Big Fish Expeditions
runs yearly trips aboard the Rocio Del Mar. These trips concentrate
on elasmobranch species.
Clark, T.B., Smith, W.D. & Bizzarro, J.J. 2006.
Mobula thurstoni. The IUCN Red List of Threatened Species 2006: