Not just Shark
Pictures: Elasmodiver contains photos of sharks, skates, rays, and
chimaera's from around the world. It began as a simple web based
field guide to help divers find the best places to encounter
different species of sharks and rays but it has slowly evolved into
a much larger project containing information on all aspects of shark
diving and photography. There are now more than a thousand shark
pictures and sections on shark evolution, biology, and
conservation. There is a large library of reviewed shark books, a
constantly outdated shark taxonomy page, a monster list of shark
links, and deeper in the site there are numerous articles and
stories about shark encounters. Elasmodiver is now so difficult to
check for updates, that new information and pictures are listed on
an Elasmodiver Updates Page that can be accessed here:
If you're looking
for a broader range of marine life pictures the following links
represent a new area of elasmodiver.com that contains pictures of
other marine organisms and of marine habitats. This expansion of
Elasmodiver is in its first stages but will eventually include pages
on all types of marine mammals, bony fishes and marine invertebrates
as well as coastal habitats, reefscapes and other imagess relating
to the ocean. Please return regularly to enjoy the progress.
芒基蝠鱝China Mandarin,
芒基蝠鲼China Mandarin,
Diabolo mantaGalapagos IsSpanish, DwergduivelsrogNetherlandsDutch,
Manta de MunkSpainSpanish,
Manta violáceaMexicoSpanish,Mante de MunkFranceFrench.
Identification:
Rhomboid disc.
Under slung mouth. No tail spines. Dorsum black, purple or purple-grey. Leading
edge of pectoral fins fading to blue-grey. Ventrum white. Long caudal filament
when intact.
Size: Maximum
disc width 220cm.
Habitat:
Shallow inshore waters. From surface to sea
floor.
Abundance and distribution:
Munk's devil rays can be found in the Eastern Pacific region from Baja California
to Peru including the Galapagos Islands, Cocos Island and Malpelo.
Diet:
The
smoothtail mobula feeds mostly of planktonic crustaceans
(mysid shrimp) but will also consume very small fishes.
Behaviour: Munks
devil rays can be solitary but are more often encountered
in immense schools which glide in unison over the seabed in search of food.
These rays are
famous for their acrobatic breaches in which one or more animals launch
themselves into the air and spin or summersault apparently out of control before
slapping back onto the surface. Sometimes many animals will jump at once leading
to the nickname 'popcorn rays' as they appear to explode randomly in all directions.
The reason that
these rays breach is unclear. Some scientists have suggested that it is to
remove parasites but it appears (from my personal observations) that the rays
usually jump in pairs, so it may be some kind of courting behavior.
Reproduction:
Ovoviviparous. One pup per litter.
Vulnerability:
Munks devil ray is assessed as 'near threatened' by the IUCN
due to its episodically high catch rates from
gillnet fisheries, restricted range and low reproductive potential.
Justification:
"The large schools, migratory nature, and
demersal feeding of M. munkiana make it highly susceptible to coastal
demersal gillnet fisheries throughout its range. Fishery information for this
species is limited to the Gulf of California, México, where it is landed in a
mixed mobulid fishery south of La Paz, México and in nearshore artisanal
elasmobranch fisheries throughout the Gulf of California. A fecundity of one pup
per female emphasizes the limited reproductive potential and low productivity of
this species. Sporadically high landings (>60 per gillnet) in the northern Gulf
of California stress the vulnerability of M. munkiana to bottomset
gillnets and the extreme fluctuations in its local abundance. Life history
characteristics, limited distribution, and exposure to many fisheries due to its
highly migratory nature will likely result in designation of the species as
Vulnerable should additional fisheries details become available".(Bizzarro, J.J., Smith, W.D. & Clark, T.B. 2006. Mobula munkiana. In:
IUCN 2010. IUCN Red List of Threatened Species. Version 2010.2).
Photographs:
Cabo Pulmo, Sea of Cortez, Baja, Mexico.
Similar species:
Mobula rays are very difficult to differentiate in the field. Within the Sea of
Cortez there are three other recorded mobulids: the bentfin devilray (Mobula
thurstoni) which has a concave area on the leading edge of its pectoral fin, the
Chilean Devil Ray (Mobula tarapacana) which is a large spineless mobula with
strongly swept back curved pectoral fins and an olive/brown dorsum, and the
spinetail mobula (Mobula japonica) which has a long caudal filament (tail) with
spines and a white tipped dorsal fin.
Reaction to divers:
Devil rays do not usually allow divers to get close
especially if they are producing noisy scuba bubbles. Patience and some skill at
breath holding may produce better results.
Diving logistics:
It is possible to encounter enormous schools of Munks devil rays in the shallow
bays in Southern Baja. Guides with Pangas are available for hire in Cabo Pulmo
where the rays are extremely abundant from late February to early April.
