Finetooth shark
A slender, schooling requiem shark of shallow western Atlantic waters.
The finetooth shark (Carcharhinus isodon) is a requiem shark that lives in the western Atlantic, from North Carolina down to Brazil. It swims in big schools in shallow coastal waters and moves with the seasons to stay in warm water. This shark is slender and small, with needle-like teeth, a dark blue-gray back, and long gill slits. It grows up to 1.9 meters (6.2 feet) long. Its diet is mostly small bony fish, especially menhaden. Like other requiem sharks, it gives live birth, with females having two to six pups every other year in estuary nurseries.
People fish for this shark for its meat, and it’s a key part of the commercial gillnet fishery off the southeastern United States. So far, population checks show that fishing isn’t hurting U.S. numbers. The finetooth shark isn’t known to be dangerous to humans, but it snaps hard when caught, so you need to be careful handling it.
**Taxonomy and phylogeny** French zoologist Achille Valenciennes first described the finetooth shark in 1839, calling it *Carcharias (Aprionodon) isodon*. The type specimen was a 65-cm (26-in) young male, possibly caught near New York. Later, it was moved to the genus *Carcharhinus*. The name *isodon* means “equal teeth” in Greek, referring to the similar number of teeth in the upper and lower jaws. It’s also called the eventooth shark, smoothtooth shark, or night shark (though that last name usually refers to *C. signatus*).
Like most *Carcharhinus* species, its family tree is tricky. In 1988, Leonard Compagno grouped it with the spinner shark, blacktip shark, graceful shark, and smooth tooth blacktip shark based on body shape. Gavin Naylor’s 1992 study using allozymes found it’s the second most ancient member of the genus, after the blacknose shark. Mine Dosay-Akbulut’s 2008 work on ribosomal DNA suggested its closest relative is the smalltail shark, and the two form a separate branch from other *Carcharhinus* species.
**Description** The finetooth shark has a slim, streamlined body. Its snout is long and pointed, with short, broad skin flaps in front of the nostrils. The eyes are big and round, with protective third eyelids. The mouth is wide, with clear furrows at the corners. It has 12 to 15 tooth rows on each side of the upper jaw and 13 to 14 on each side of the lower jaw.
Quick Facts
- Genus
- Carcharhinus
- Species
- isodon
Facts from the source article.
Lore & Background
The finetooth shark was originally described as Carcharias (Aprionodon) isodon by French zoologist Achille Valenciennes in 1839. The specific epithet isodon means 'equal teeth' in Greek, referring to the similar number of teeth in the upper and lower jaws. Its body is slender and streamlined, with a long pointed snout, large round eyes, and needle-like teeth. The first dorsal fin is high and triangular, and the second dorsal fin is relatively large. Living finetooth sharks are dark bluish-gray above and white below, with no prominent fin markings.
This species is common from North Carolina to the northern Gulf of Mexico, and rare in Central and South American waters. It inhabits extremely shallow waters, no deeper than 10 m in summer and 20 m in winter. The northwestern Atlantic population is strongly migratory, arriving off South Carolina from late March to early May when water temperature rises above 20 °C, and moving south to Florida in autumn. Adults and juveniles form large schools and feed mainly on small bony fishes, especially Atlantic menhaden, which are swallowed whole after the head is removed.
Like other requiem sharks, the finetooth shark is viviparous, with a 12-month gestation period. Females produce litters of two to six pups every other year, giving birth in estuarine nursery areas. Males mature at around 5 years in the northwestern Atlantic and 4 years in the Gulf of Mexico; females mature at 6 and 5 years, respectively. The finetooth shark is not known to pose a danger to humans, though it snaps vigorously when captured.
Reader's Guide
The finetooth shark is valued for its meat and forms an important component of the commercial gillnet shark fishery off the southeastern United States. Substantial numbers are caught in drift gillnets, with landings peaking at about 117 tons in 1999. Stock assessments conducted in 2002 suggested that U.S. populations had not yet been overfished, indicating that the fishery does not currently pose a threat. However, the species is susceptible to overfishing due to its low reproductive rate and to habitat degradation due to its inshore habits. Other than off the southeastern United States, it is of little commercial importance because it is small, occurs in very shallow water, and is too fast-swimming to be caught by shrimp trawlers. Small numbers are taken incidentally by floating longlines and hook-and-line. The finetooth shark has never been implicated in an attack on humans, but should be handled with caution when captured.
Did You Know?
- It feeds primarily on Atlantic menhaden, which it swallows whole after removing the head.
- Females give birth to two to six pups every other year after a 12-month gestation period.
- The largest finetooth shark on record was 1.9 m (6.2 ft) long.
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