Blacknose shark
A small requiem shark with a distinctive dark snout tip.
The blacknose shark (*Carcharhinus acronotus*) is a requiem shark from the family Carcharhinidae. It lives in the western Atlantic Ocean’s tropical and subtropical waters, sticking to coastal areas with seagrass, sand, or rubble. Adults tend to stay in deeper water than the young. This shark is small, usually reaching about 1.3 meters (4.3 feet) in length, and gets its name from the dark mark on the tip of its snout, though this blotch can become less noticeable in older sharks. It has a streamlined body typical of requiem sharks, with a long, rounded snout, large eyes, and a small first dorsal fin. There are no known attacks on humans, but it has been seen performing a threat display toward divers.
The blacknose shark mostly eats small bony fish and cephalopods, and larger sharks prey on it. Like other requiem sharks, it gives birth to live young that are nourished through a placental connection during development. Females produce litters of three to six pups in late spring or early summer, either every year or every other year, after a gestation period of eight to 11 months. This species has moderate value for both commercial and recreational fishing. In 2009, the U.S. National Oceanic and Atmospheric Administration reported that blacknose shark populations off the United States were being overfished and suggested new conservation steps.
Quick Facts
- Genus
- Carcharhinus
- Species
- acronotus
Facts from the source article.
Lore & Background
The Cuban naturalist Felipe Poey first described the blacknose shark in 1860 as Squalus acronotus, based on a 98-cm male caught off Cuba. Later authors moved it to the genus Carcharhinus. Its phylogenetic relationships remain uncertain: morphological data by Jack Garrick in 1982 suggested a sister relationship to a group containing the whitecheek shark and blackspot shark, while Leonard Compagno in 1988 placed it with five other species including the silky shark and blacktip reef shark. Molecular analyses have been equivocal, with Gavin Naylor's 1992 allozyme study finding it the most basal member of Carcharhinus, and Mine Dosay-Abkulut's 2008 ribosomal DNA analysis indicating affinity with the blacktip shark or smalltail shark. The whitenose shark may be descended from blacknose sharks that experienced teratogenic effects of incipient cyclopia.
The blacknose shark has a slender, streamlined body with a long, rounded snout and large eyes. Its first dorsal fin is small and sickle-shaped, and no ridge exists between the dorsal fins. The coloration is yellowish to greenish-gray or brown above and white to yellow below, with a distinctive dark blotch on the snout tip most obvious in young sharks. It feeds primarily on small bony fishes and cephalopods, and in turn falls prey to larger sharks. It may form large schools and demonstrates high philopatry, returning to the same local area year after year.
Reader's Guide
The blacknose shark is of moderate commercial and recreational importance. It is regarded as a game fish and offers a respectable fight on light tackle. It is taken intentionally and as bycatch via gillnets and surface longlines across its range, most significantly off southwestern Florida, Venezuela, and Brazil; the meat is sold dried and salted. Large numbers are also caught incidentally by shrimp trawlers, which may pose a greater threat to its population as many taken are immature. In 2009, the U.S. National Oceanic and Atmospheric Administration announced that populations off the United States are being overfished and proposed new conservation measures. The species has never been implicated in an attack on humans, but caution should be exercised if it performs a threat display, which involves hunching its back, lowering pectoral fins, gaping jaws, and swimming with an exaggerated side-to-side motion. Known parasites include several copepod species and tapeworms in the genera Paraorygmatobothrium and Platybothrium.
Did You Know?
- The blacknose shark was first described by Cuban naturalist Felipe Poey in 1860 as Squalus acronotus.
- It performs a threat display towards divers by hunching its back, lowering pectoral fins, and gaping its jaws.
- Females give birth to litters of one to six pups in shallow nursery areas such as coastal bays or mangrove swamps.
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