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constantly outdated shark taxonomy page, a monster list of shark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.
Common
Names: Bull
shark, Zambezi shark, Lake Nicaragua shark, Cub shark.
Latin
Name: Carcharhinus
leucas
Family:
Carcharhinidae
Identification:
Heavy
set body. Broad, short snout. Eyes proportionately small. First dorsal large and
pointed. Upper body uniformly grey fading to paler grey on the belly. Tips of
all fins and trailing edge of caudal fin are sometimes dusky. No interdorsal
ridge.
Size:
Maximum
length 340cm. Size at birth 56-81cm.
Habitat:
Turbid inshore waters, lagoons, estuaries, freshwater rivers and lakes,
coastlines, and reef environments down to 150m. The Bull shark is famous for its
habit of occasionally swimming upstream hundreds of miles in some river systems such as the
Mississippi, Amazon, Zambezi, and Lake Nicaragua.
Abundance
and distribution: Circumtropical
and subtropical.
Behavior: Diet
consists of many food types including bony fishes, turtles, seals, crabs, and
squid. Adult Bull sharks are especially keen on other elasmobranchs. Hunting may
take place in both salt and fresh water habitats.
Reproduction:
Viviparous.
Recorded litter size 1 - 13. Gestation period 10 - 11 months.
Observations:Bull
sharks have been observed lying motionless on the seabed as if sleeping. No
explanation for this desire to rest is immediately obvious.
Photographs:
Playa Del Carmen, Mexico.
Similar species:
In the Caribbean Sea the Bull shark is often confused with the Caribbean reef shark (C.perezi)
which is not as heavy bodied and has more distinct markings. Many carcharhinids
are superficially similar to the bull shark and attention to fin coloration and
overall body proportions are important clues to species identification. Of a
similar size or even bigger than the bull shark is the Dusky shark (C.obscurus).
The Dusky often has very little identifying markings but has a longer and more
pointed snout than the Bull.
Reaction to divers:Although Bull sharks have been implicated in
many attacks on bathers, divers are normally not harassed unless they are spear
fishing. Dr Erich Ritter was bitten 'on camera' during a
shark feed at Shark Beach in the Bahamas. The incident resulted in the lengthy
documentary - Anatomy of a Shark Bite.
Diving
logistics: There is now a new Bull Shark
feed in Playa del Carmen, Mexico. Phantom Divers in PDC take divers out to the
feed which is in 80ft of water. Up to 24 sharks sometimes visit the feed from
November to the beginning of March.
Shark
Beach AKA Bull shark Beach at Walkers Cay in the Bahamas was at one point the
best location for viewing Bull sharks in the world. In 2003 it was closed. Erich
Ritter's injury was probably a contributing factor to the closure but the entire
resort fell victim to a fierce hurricane.
Another
excellent area for Bull shark encounters is the Coastline of southern Africa
around Protea Banks, and Aliwol Shoal. Many operators service these areas from
South Africa and Mozambique and a list of companies can be found in the
elasmodiver links section. Any recommendations from divers of specific outfits
would be welcome.
References
and further
reading:
Sharks of Tropical and Temperate Seas. - R.H.
Johnson - Pisces Books
Reef
Sharks and Rays of the World. Scott W. Michael. Sea Challengers.
Sharks
and Rays - Elasmobranch Guide of the World. Ralf M. Hennemann. IKAN.
