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constantly outdated shark taxonomy page, a monster list of shark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:
Large
size. Dorsal fin proportionately very high and falcate. Leading edge of hammer
almost straight with central indent. Body brown to greyish brown. Ventral
surface pale.
Size:
Maximum
length 6 metres. 50 - 70 cm at birth.
Habitat:
In shore and off shore reefs and surrounding tropical ocean environments.
Intertidal to 80 meters.
Abundance
and distribution: Circumtropical.
Behavior:Cruises
over sand and reefs in search of prey. Pins stingrays to the sand with hammer
whilst disabling them. Swims with an exaggerated swaying of the hammer in order
to see forward.
Reproduction:
Viviparous.
The hammerhead are considered the most highly evolved of the shark families.
Observations:In the
Bahamas I observed yellow jacks rubbing themselves along the flanks of Great
Hammerheads possibly ridding themselves of parasites. This shark was observed in
the presence of many other reef sharks which are reported to avoid it. The
presence of chum in the water may have affected normal social boundaries.
Photographs:
Outer Bahamas.
Similar species:Scalloped
hammerhead distinguished by more pronounced scalloping of hammer and
proportionately smaller fins, Smooth Hammerhead distinguished by total lack of
indentations in leading edge of hammer, and Smalleye hammerhead distinguished by
small size and highly convex anterior margin of hammer.
Reaction to divers:Shy. Moves
away unless in a baited situation. May become very bold and make close passes at
divers but not normally aggressive. Care should be taken due to large size and
previously reported attacks on bathers.
Diving
logistics:
Jim and Anna Abernethy run
week long Hammerhead and Tiger shark trips to the Bahamas from Palm Beach. Chum
is used to attract the sharks with which they have had great success.
These shark safaris also attract many Caribbean reef sharks and participants
should be aware that no cages are used. In my opinion the experience of diving
with such large sharks without the restrictions of a cage is second to none.
Read the trip report entitled: Hammers and Tigers in the Bahamas.
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.
