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constantly outdated shark taxonomy page, a monster list of shark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.
Identification:
Snout laterally pointed.
Well developed labial furrows. Eyes small and round. Interdorsal ridge absent.
Dorsum grey with indistinct white line on flank. Ventrum white. Distinct
and boldly delineated black tips on all fins except pelvic and upper caudal.
Anal fin more 'hooked' than in most large reef sharks. Angular torso with well
defined lateral line. Teeth narrow cusped.
Size:
Maximum
length 278cm. Size at birth 60-75cm.
Habitat:
Continental coastlines from inshore to edge of shelf. Surface waters to bottom
at 75m. Also above surface when breaching!
Abundance
and distribution: Western Atlantic from
Carolinas to Gulf of Mexico. Also southern Brazil. Occasional Caribbean and
northern Brazil. Eastern Atlantic around western Africa and Southern
Mediterranean Sea.Around
perimeter of Indian Ocean from Madagascar to South Africa. Also India, South
East Asia and Australia. North Pacific Japan and Philippines.
Behavior:Known
to undertake mass migrations; aerial footage of enormous
schools of spinner sharks off of eastern Florida have been used by the media to
exaggerate the dangers of beach swimming. When feeding, vertical upward attacks
on surface fish sometimes lead to spectacular spinning jumps from the water,
hence common name.
Diet: consists mainly
of bony fishes but some stingrays and cephalopods are also consumed.
Reproduction:
Viviparous.
Yolk sac placenta. Recorded litter size 3 to 15. Litter size increases with size
of female.
Photographs:
Gulf of Mexico, Louisiana,
USA.
Similar species:
Because of its extensive range it is difficult to list every carcharinid shark
that looks somewhat similar to Carcharhinus brevipinna. Field
identification is difficult but the spinner shark's highly laterally pointed
head, distinct black fin tips (except anal and upper caudal) and unique
breaching behavior are a good place to start.
Reaction to divers:
The spinner shark is very hard to approach. Although it is commonly seen by
fishermen when breaching, it quickly moves away when divers enter the water. The
grainy image above was taken from a distance while surface snorkeling with a
large school of silky sharks. Two spinners were attracted by the chum slick but
they refused to approach the bait and stayed far below the much bolder silkies.
Video from Western Australia indicates that spinner sharks grow much more
aggressive around bait balls and may ignore divers completely.
IUCN Red List status: Near threatened. Vulnerable to fishing
pressure and habitat degradation.
Diving
logistics: Please email elasmodiver with information on sites where
scuba diving or snorkeling with spinner sharks is possible.
