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a large library of reviewed shark books, a constantly outdated shark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:
Long conical snout. Large blue/black eyes. Lower jaw contains multiple rows of
inwardly curving teeth. Pectoral
fin length shorter than length of head.
Juveniles often have more rounded dorsal and pectoral fins. Well developed
caudal keel. Crescent shaped tail. Back coloration bright blue to purple/slate
grey. Underside off white. In the Shortfin Mako Shark population of the Azores
and Cape Verde Islands the underside of the snout and jaw of large adults are
dusky which is similar to the Longfin Mako's coloration but characteristic
analysis confirms that they are definitely Isurus oxyrinchus.
Size:
Maximum recorded size 4.45m but more commonly 2m. Size at birth 60-70cm
Habitat: Coastal
and oceanic in depths of up to 500m.Prefers clear water over turbid.
Often seen swimming just below the surface with first dorsal fin visible.
Abundance
and distribution: Circumtropical
and temperate in waters usually warmer than 16 degrees. Highly
migratory with migrations recorded up to 2500mi.
Diet and Behavior:Cruises
open water in search of prey species.
Main diet consists of bony fishes and squid. Wounds and scars on the ventral
surface and caudal peduncle of swordfish and tuna indicate that Shortfin Mako
Sharks often attack from below. As well as a large assortment of bony fishes,
Makos also consume a variety of sharks and rays (especially in South Africa) and
larger specimens may attack dolphins and small cetaceans.
Reproduction:
Ovoviviparous.
Recorded litter size 2 - 10 but may be higher. Gestation has been estimated at
14 months.
Observations:On a recent trip to Guadalupe
Island I watched a small (1m) Shortfin Mako
make
repeated passes at the shark cage whenever the Great White Sharks disappeared.
Photographs:
San Diego,
California.
Similar species:Longfin Mako (Isurus paucus) distinguished by significantly
longer pectoral fins, even larger eyes and dark coloration on the underside of
the snout and jaw extending about half way to the gills. Teeth are also somewhat
broader.
Reaction to divers:
Initially makes fast, close passes in the presence of chum then slows
down and retreats to a more wary distance but continues to make occasional
passes. Otherwise difficult to approach. Rarely attacks without provocation but
has bitten divers and swimmers. Also known to attack boats.
Diving
logistics:
Chris Fallows runs an ecotourism operation in South Africa in which Mako and
Blue Sharks are commonly seen.
Until recently there were Blue/Mako Shark operators working out of Southern
California but due to over-fishing fewer and fewer sharks attended the feeds
until shark watching trips were no longer viable.
Other diving locations submitted by
readers:
References
and further
reading:
Mako Sharks. Alessandro De
Maddalena. Krieger.
Sharks of the World. Leonard
Compagno.
Sharks
and Rays - Elasmobranch Guide of the World. Ralf M. Hennemann. IKAN.
