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a large library of reviewed shark books, a constantly outdated shark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 that contains pictures on other marine
organisms and on marine habitats. This expansion of Elasmodiver is
in its first stages but will eventually include pages on everything
from sea stars to nudibranches. Creating this portal will take time
and for now it consists of a token offering of fish pictures. Please
return regularly to enjoy the progress.
Identification:
Bluntly rounded snout. Seven gill slits, posterior slits very short. Single
dorsal fin set well back on body. Upper body sprinkled with small black spots
and usually some white spots. Large size.
Size:
At birth 34-45cm. Males mature at 130-170cm. Females mature at 200cm. Maximum
recorded size 290cm. May possibly grow to 400cm.
Habitat:
Coastal sandy bays and rocky shorelines up to the surf line.
Larger individuals inhabit deeper channels. Recorded at 136m but usually found
in 1-50m.
Abundance
and distribution: Temperate
coastal waters around the world. Southern Australia, New Zealand, Japan,
Southern Africa, east and west coasts of south South America, and west coast of
North America to Alaska.
Behavior
and Diet:
Cruises steadily along bays in search of food moving in and out with the tides.
Prefers low visibility - night, turbid water, overcast conditions. Known to
aggregate possibly for mating. Footage from the documentary Shark Quest shows a
group of Broadnose Sevengill Sharks feeding together on a stingray carcass.
Preys on sharks and rays, bony fishes and marine mammals.
Reproduction:
Ovoviviparous
(aplacental viviparous).
Litter size 67-104. but may be higher. Gestation probably around one year
followed by one year of recovery.
Observations:
Broadnose Sevengill Sharks have been observed spy hopping - holding their heads
above water and seeming to look around. This behavior is rare among sharks but
has been regularly observed in Great White Sharks. it is possibly an adaptation
to aid in the capture of marine mammals.
Similar species:
The Bluntnose Sixgill Shark (Hexanchus griseus) has a very similar body
shape but lacks the seventh gill slit and has less or no spots. The Sharpnose
Sevengill Shark (Heptranchias perlo) has much larger eyes, a more pointed
snout, and flattened, elongated pelvic fins.
Reaction to divers:
The Broadnose Sevengill shark can become aggressive in baited situations e.g.
towards spear-fishermen. In captivity it has bitten aquarium divers.
Diving
logistics:
Although this shark has a broad distribution it is not commonly encountered by
divers. Probably South Africa and South Australia offer the best opportunities
for sightings.
Other diving locations submitted by
readers:
References
and further
reading:
Reef
Sharks and Rays of the World. Scott W. Michael. Sea Challengers.
Sharks
and Rays - Elasmobranch Guide of the World. Ralf M. Hennemann. IKAN.
