|Photo modified from
Sharks and Rays. TC Tricas, K Deacon, P Last, JE McCosker, TI Walker, L
Taylor. 1997. Nature Company Guides, Time Life Book Series. Weldon Owen Pty Ltd
The dusky shark has a long
streamlined body that is brown or gray above and white below. There is a faint
lateral stripe that extends to the pelvic fin. Juveniles have a dark
colouration on the tip of the caudal fin and the underside of the pectoral fins
that is less pronounced in adults. The first dorsal fin is much larger than the
second with a dermal ridge found between the two dorsal fins. The upper lobe of
the caudal fin is larger than the lower lobe. The pectoral fins are long and
curved on the trailing edge. The dusky shark can grow to 4 meters (13 feet) in
length. The upper teeth of the dusky shark are broad and triangular with a
serrated edge, but while the front teeth are virtually erect, the others are
slightly oblique. The lower teeth differ since they have narrow, erect cusps
with more finely serrated edges than the upper teeth.
The diet of this shark
includes small schooling fish such as sardines and anchovies, as well as larger
fish like tuna, mackerel, flatfish and eels. The dusky shark also eats dogfish,
catsharks, skates and rays.
Females become sexually
mature at about 3.0 meters (10 feet), while males become sexually mature at 2.9
meters (9.5 feet). They are viviparous and females give birth to a litter of 6
to 14 pups. After 16 months gestation the pups are delivered at a size of
approximately 95 cm (3 feet).
The dusky shark lives in
warm temperate continental waters. The specimens captured in Canadian waters
were found at a water temperature of 19 degrees Celsius.
This shark is found in the
Atlantic, Pacific and Indian Oceans. In the western North Atlantic the northern
most part of the range is Georges Bank. They continue to be found southward to
the Caribbean Sea, the Gulf of Mexico and through to Brazil.
- Dermal ridge between the first and second
- Upper and lower teeth nearly
- Nictitating membrane over eye