Genus: Rhizoprionodon, Sharpnose Sharks
RHIZOPRIONODON
SHARPNOSE SHARKS
Body slender to moderately stout; snout long, pointed (as long as width of mouth); small, widely spaced nostrils; with long furrow over rear of top lip; no spiracle; large round eyes; front teeth on both jaws, with narrow, oblique points, may be serrated; five gill slits, last two over pectoral; two dorsal fins, first much larger, with origin ~ over rear margin of pectoral; second dorsal origin ~ over rear insertion of anal, fin slightly smaller than anal fin; no or rudimentary ridge between dorsals; pectorals broad, triangular; anal fin with a long, conspicuous ridge before it on each side; rear edge of anal fin ~ straight; tail base with a crescentic transverse pit on top, another pit under bottom; tail fin strongly asymmetrical, lower lobe of tail well developed, upper lobe with undulating ridge along its top edge, and a notch under its tip, pits at its base.
A circumtropical genus, except for central Pacific. There are seven species in this genus, one of which is endemic to the tropical eastern Pacific.