GREAT WHITE SHARK

Description

A large, heavy-bodied shark of fusiform shape, with crescentic tail - caudal fin, snout conical, blunt and dorsally flattened. The five gill-slits are large but not encircling the head. 

First dorsal fin broad, nearly an equilateral triangle, with a slightly concave rear margin and its origin above or slightly posterior to the axil ('armpits') of the pectoral fins. The first dorsal is rounded at the apex in neonates but becomes more acutely-pointed within the first two years

Second dorsal fin is very small and pivotable, lying slightly ahead of the equally-small anal fin. The broad, dorsoventrally depressed caudal peduncle is expanded laterally to form a prominent keel on either side, but without secondary keels on the ventral caudal lobe itself (as in the porbeagle Lamna nasus).  

The lunate caudal fin tends to have acutely-pointed tips in sharks over 2.0 m TL. In neonates, the lower (ventral) caudal surfaces may be more rounded and compressed but rapidly expand soon after birth. The caudal lobes are almost of equal size, with the lower (ventral) anterior margin measuring 76-92% of the same measurement on the upper (dorsal) lobe. The pectoral fins are large and moderately falcate.

Vertebral count is between 172-187. 





Teeth are large, essentially broad and triangular, with notably serrate margins, distinguishing this species from the other lamnids (which all have smooth-edged teeth); tooth count 23-28 in upper jaw, 21-25 in lower. 


Newborns, juveniles under 1.8 m, have narrower teeth, with basal cusps on the lower jaw teeth, and in neonates, anterior lower-jaw teeth may essentially lack marginal serrations. 

Colour

Colour vary from almost black to typically slate-grey or olive-brown above, often with a bronzy sheen on the flanks, with the ventral surfaces predominantly white.

A strong, variable and blotchy (particularly near the gill-slits and above the pelvic fin bases) line of demarcation separates the dark upper and white lower surfaces (dorsal and ventral surfaces). Underside of pectoral fins tipped with black; a black, oval blotch often present in the axil of the pectorals although this is sometimes absent on Mediterranean specimens. Small, irregular dark spots may be present on the flanks posterior to the 5th gill slit and the lateral surfaces have a bronzy sheen that may be structural and manifested only in strong sunlight.

The ventral tips of the pectorals are black and most specimens exhibit a black oval blotch in the axil of the pectoral fin. The pelvic fins may be blotched with olive or grey; likewise the ventral caudal lobe, with white marks and white anterior booting. The mode of these demarcations vary greatly individually, but may exhibit common trends amongst sharks in a given geographical remit. The variance in dorsal pigment and tone is also very variable, especially between centers of abundance but also within them. Californian examples are often very dark slate-grey above, almost black. South African examples (Cape Province) tend to be somewhat more dun or olive, as do Australian specimens (but with much variance). Mediterranean specimens are predominantly slate-grey or dark olive-brown dorsally.