Not just Shark
Pictures: Elasmodiver contains photos of sharks, skates, rays, and
chimaera's from around the world. Elasmodiver began as a simple web
based shark field guide to help divers find the best places to
encounter the different species of sharks and rays that live in
shallow water but it has slowly evolved into a much larger project
containing information on all aspects of shark diving and shark
There are now
more than 5000 shark pictures and sections on shark evolution,
biology, and conservation. There is a large library of reviewed
shark books, a constantly updated 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:
Disc width roughly twice length. Dorsum covered in
an intricate pattern of tiny lines and swirls that form light and dark brown
spots and larger irregular circles fringed with white. Ventrum white,
cream or with a pinkish hue. Short tail has one or two tail stings (unborn
embryos already have fully formed tail stings). Dorsal fin absent. Very low
dorsal and ventral finfolds on tail.
span to 400cm.
Sandy or muddy bays and brackish estuaries,
reef faces, and over sand flats. 2 to 100m depth.
Abundance and distribution:
Occurs in the eastern Atlantic Ocean from Portugal to Angola including the
Canary Islands, Madeira, and the Mediterranean and Black Seas. Also occurs in
the western Atlantic Ocean from Massachusetts to Argentina.
Lays motionless for much of the time under a thin covering of sand. Butterfly
ray footprints or beds (indentations left in the sand) can often be seen days
after the animal has moved on.
Feeds on fishes, crustaceans, mollusks and plankton.
4-7 embryos. Gestation lasts for about 6 months. Once the unborn spiny butterfly
rays have completely used up the reserves in the yolk sac, the mother secretes
uterine milk. Long villi (filaments) grow from the uterus walls into the
embryo's spiracles. Milk can then be directed more efficiently into the embryo's
mouth and throat.
Photographs: Los Gigantes, Tenerife,
Canary Islands, Eastern Atlantic Ocean.
Another species that shares the western range of the spiny butterfly ray is the
Smooth Butterfly Ray Gymnura micrura.
Reaction to divers:
If buried in the sand, the spiny butterfly ray will often remain motionless
while divers pass. Even after most of the sand has
been fanned away (as in the above picture) these rays are likely to remain
stationary as long as the observer uses slow, non threatening movements.
Spiny butterfly rays
are fairly abundant around the Canary Islands. Reportedly, there is one that has
taken up residence in the harbor on El Hiero. I have seen many beds in the El
Cabron Marine Park but no actual animals.
Occasionally spiny butterfly rays attend the organized ray feeds at
Los Gigantes on Tenerife (where the featured specimen was seen). Los Gigantes Diving offers freestyle feeds
once or twice per week. The divemaster takes a huge barrel of fish scraps to
60ft and offers them to the eagerly gathering ray species. After a while the
human participants usually help themselves to some fish and wander off to
interact with the rays on their own. The feed can be rather chaotic but the ray
action is almost guaranteed. Attending species include common eagle rays, common stingrays, roughtail rays, round stingrays and
occasionally angel sharks, butterfly rays, and marbled torpedo rays.
Very occasionally a large Bull Ray swims by. Contact Los Gigantes Dive Centre for further information.
and Rays - Elasmobranch Guide of the World. Ralf M. Hennemann. IKAN.