Common
Names: Sandtiger
shark, Common sandtiger shark, Ragged-tooth shark, Spotted ragged-tooth shark,
Raggie, Grey nurse shark, Sand shark.
Latin
Name(s):
Carcharias
taurus, Eugomphodus taurus.
Family:
Odontaspididae.
Identification:
Exposed
ragged appearing teeth in jaw. Nares and upturned snout create a snarling
appearance. Bulky mid body. First dorsal fin set far back over pelvic fins. Anal
fin large - same size as pelvic fins and second dorsal. Dorsal colouration brown
to greyish gold usually with scattered darker spots or blotches. Ventral colouration
pale.
Size:
Maximum
length 2.6m (male), 3.3m (female). Length at birth 1m
Habitat:
Found around rocky reefs and wrecks in temperate and tropical waters.
From the surface to
200m or more.
Abundance
and distribution: A wide
ranging coastal species.
A frequent inhabitant of shipwrecks on Americas eastern seaboard
especially around North Carolina. Also encountered in reef channels
around New South Wales (Australia), and at rocky reefs off South Africa.
Inhabits deeper water in the Mediterranean. Also commonly seen off Japan.
Populations inhabiting higher northern latitudes will move to warmer water in
the winter, whilst more tropical groups are often present year round.
Behavior: Often
seen hovering motionless above the bottom. A behaviour achieved by its ability
to swim to the surface and swallow air.
The stored air allows the shark to float in the same way as a fishes gas filled
swim bladder. Although docile the Sandtiger has the ability to lunge
forward with great speed when hunting or defensively. Diet varies according to
location but generally consists of bony fishes and smaller sharks and rays.
Reproduction:
Ovoviviparous
and embryophagous i.e. developing embryos practice intrauterine cannibalism
until just one baby shark remains in each uterus. Mating aggregations
have been observed. Males (in captivity) have been seen to bite females around
the gill region to hold on during copulation. Females stop feeding during
pregnancy to the point where hydroids have been observed growing on their
teeth.
Observations:
Photographs:
North
Carolina.
Similar
species: Smalltooth
sandtiger (Odontaspis ferox). Identified by bulkier conical snout, larger and
further forward first dorsal.
Reaction
to divers: Remains
motionless unless very closely approached. Not normally aggressive towards
divers but males may become more aggessive during courtship.
Diving logistics: Companies
out of North Carolinas' Cape Hatteras and Moorhead City run day charters to
various wrecks along the Carolina Coast. I have dove repeatedly with John and
Amy Pieno who run Outer Banks Diving out of Hatteras and have seen upto 100
Sandtigers on one dive. This was the first dive of the season and the sharks
tend to move away from the most visited wrecks as the season progresses but a
few are usually still hanging around for a portrait.
Other diving locations submitted by readers:
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.
The Shark Watchers Handbook - Mark Carwardine and Ken Watterson.
