Caribbean Sharpnose SharkRhizoprionodon porosus
This small requiem shark was recently identified as a different species from the Atlantic sharpnose shark. It has the same slender body, pointed snout, and gray-brown coloring that fades to a white underside. The Caribbean sharpnose shark has more precaudal vertebrae. These small sharks are considered harmless to humans because of their small size (averaging 35 inches long), and their preference for small prey items.
English language common names are Caribbean sharpnose shark, Atlantic sharpnose shark, sharpnose shark, and snook shark. Other common names include cação (Portuguese), cação-frango (Portuguese), Caribische scherpsnuithaai (Dutch), cazón de ley (Spanish), cazon picudo (Spanish), frango (Portuguese), nokkahai (Finnish), requin aiguille antillais (French), tollito (Spanish), tollo hocicón (Spanish), tribon cabez largu (Papiamento), and tribon mula (Papiamento).
Importance to Humans
There is a limited commercial fishery for this species along the coast of Brazil. It is also caught in the artisan fisheries of Central America. The Caribbean sharpnose shark is caught with hook and line or longline. It is also sometimes captured as bycatch in shrimp trawls and is often considered a nuisance by fishers. The flesh is marketed salted or frozen for human consumption, as well as processed into fish meal.
The Caribbean sharpnose shark adapts to captivity and is successfully kept in large public aquariums.
Danger to Humans
This shark is considered harmless to humans primarily due to its small size and preference for small prey items. It avoids contact with humans and is difficult to approach while diving.
The IUCN is a global union of states, governmental agencies, and non-governmental organizations in a partnership that assesses the conservation status of species.
Geographical DistributionThe Caribbean sharpnose shark is limited in distribution to the western Atlantic Ocean from the Caribbean region, including the Bahamas, south to Uruguay. At this time, it is still uncertain if this species is actually a distinct species or a southern subspecies of the Atlantic sharpnose shark (R. terraenovae).
This locally abundant shark resides close inshore, primarily in tropical bays and estuaries with occasional forays into freshwater rivers. It is also reported to live in offshore waters to depths of 1,640 feet (500 m), although more commonly in depths less than 328 feet (100 m).
The Caribbean sharpnose shark has a slender fusiform body and long snout. The long labial furrows are present around the corners of the mouth. The first dorsal fin is typically over or just behind the free tips of the pectoral fins; the origin of the second dorsal fin is either just over the anal fin midbase to over the rear quarter of its base. The anterior margin of the pectoral fins is usually a bit longer than the first dorsal length from origin to free rear tip. The origin of the anal fin is anterior to the second dorsal fin origin. The margin of the anal fin is either straight or slightly concave.
The similar smalltail shark (Carcharhinus porosus) can be distinguished from the Caribbean sharpnose shark by its serrated teeth as well as the absence of long labial furrows.As the northern reaches of the Caribbean sharpnose shark's range is approached, it is replaced by a very similar, closely related species, the Atlantic sharpnose shark (Rhizoprionodon terraenovae). These sharks can be distinguished only by the number of precaudal vertebrae with the Caribbean sharpnose shark having 65-75 precaudal vertebrae while the Atlantic species has only 58-65 precaudal vertebrae.
The upper surface of the body is brown or grayish-brown in color, fading to a white underside. Occasionally, this shark will be marked with white spots along the flank region. The fins have either white or clear margins.
The teeth of the Caribbean sharpnose shark are triangular with smooth-edged cusps, with a distinct notch along the outer margins. Weak serrations may be present in large individuals. The teeth are similar in both the upper and lower jaws, numbering 12 teeth on either side of the symphysial tooth in the upper jaw and 12 teeth on each side of the lower jaw. There is no sex-differentiation of the dentition between males and females.
The dermal denticles of the Caribbean sharpnose shark are very small and overlapping. The blades are as broad as long with 3-5 keels. The posterior margin has the same number of teeth with the median tooth slightly longer than the others.
Size, Age, and Growth
The maximum reported size of the Caribbean sharpnose shark is 43 inches (110 cm) total length. However, the average size of this shark is approximately 31 inches (80 cm) in length. Males reach sexual maturity at 26-28 inches (65-70 cm) total length and females are mature at a total length of 26 inches (65 cm).
Small bony fishes, including wrasses, as well as marine invertebrates such as snails, squid, and shrimp provide prey for the Caribbean sharpnose shark.
The Caribbean sharpnose shark is viviparous with a yolksac placenta. It is believed that mating occurs during late winter until early summer followed by a gestation period of approximately 10 to 11 months. In Brazilian waters, birth occurs during the spring and early summer months. The litter size is 2-6 pups, with each pup measuring 12-15 inches (31-39 cm) in length.
Large sharks are potential predators of the Caribbean sharpnose shark, especially of the juveniles.
The Caribbean sharpnose shark was first described as Squalus porosus by Cuban naturalist Felipe Poey (1861). This name was later changed to the currently valid name of Rhizoprionodon porosus (Poey, 1861). The genus name Rhizoprionodon is derived from the Greek, "rhiza" = root, "prion" = saw, and "odous" = teeth. There are no known synonyms referring to this species in past scientific literature.
Prepared by: Cathleen Bester