The Finetooth shark (Carcharhinus isodon) is a species of requiem shark, in the family Carcharhinidae, found in the western Atlantic Ocean, from North Carolina to Brazil. It is a schooling shark that lives in shallow, warm coastal waters. Its teeth are fine and needle like, giving the Finetooth shark its name.
Family: Carcharhinidae – Requiem sharks
Genus: Carcharhinus
Species: isodon
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Common Name– Ground Sharks
Family– Carcharhinidae
Common Name– Requiem Sharks
Genus– Carcharhinus
Species– isodon
Status: IUCN Red List LEAST CONCERN
Average Size and Length: Male Finetooth sharks average 5.2 feet in length and females 5.4 feet in length. The largest shark on record was 6.2 feet long.
Teeth and Jaw: The mouth of the Finetooth shark is broad with well-defined furrows at the corners. 12 to 15 tooth rows occur on either side of the upper jaw and 13–14 tooth rows on either side of the lower jaw. Each tooth is small and needle-like, with a narrow central cusp and smooth to minutely serrated edges.
Head: The snout of the Finetooth shark is long and pointed, with the nares preceded by short flaps of skin. The eyes are large and round, with nictitating membranes. Some Finetooth sharks that live here in Florida have green eyes.
Denticles: The dermal denticles are small and overlapping and each denticle has 3 horizontal ridges leading to marginal teeth.
Demographic, Distribution, Habitat, Environment and Range: The Finetooth shark is frequently found near beaches and in bays and estuaries. It inhabits extremely shallow waters, no deeper than 33 feet in the summer and 66 feet deep in the winter.
In the past, it was known to venture into rivers in the Gulf Coastal Plain of Texas, though most of paths into this area are now blocked by dams. The northwestern Atlantic population of this species is strongly migratory: juveniles, followed by adults, arrive off South Carolina from late March to early May, when the water temperature rises above 68 °F. They remain until September to mid-October, until the water temperature drops and they move south to Florida. The movements of other populations are unknown. We frequently do see Finetooth sharks here in Jupiter.
In North America, the Finetooth shark is common and found from North Carolina to the northern Gulf of Mexico, and very infrequently straying as far north as New York. In Central and South America, it is rare, but may occur more widely than presently known, having been reported off Trinidad and Guyana, infrequently from the Caribbean Sea, and off southern Brazil from São Paulo to Santa Catarina.
Diet: The Finetooth usually enters the surf zone during the day to hunt for prey.
The Finetooth shark mainly eats small bony fishes. The most important prey of the Finetooth shark in the northwestern Atlantic is the Atlantic menhaden (Brevoortia tyrannus). The population of Finetooth sharks in northwestern Florida almost exclusively eats menhaden. They are swallowed whole just after removing the fishes head. Other known prey include mullet, spot croaker, Spanish mackerel, shrimp. There has been a documented case of a Finetooth shark eating another shark that it scavenged from bycatch.
The Finetooth shark can become prey to larger sharks.
Aesthetic Identification: The Finetooth shark is slender and streamlined. They five pairs of long gill-slits that measure about half the length of the dorsal fin base. Finetooth sharks that are alive are a dark bluish-gray above and counter-shaded white below, with a faint pale stripe on the flanks and no prominent fin markings. The first dorsal fin is high and triangular with a pointed apex, originating forward of the free rear tips of the pectoral fins. The second dorsal fin is relatively large and originates over the anal fin. No ridge runs between the dorsal fins. The pectoral fins are small and falcate with pointed tips.
Biology and Reproduction: Parasites of the Finetooth shark include the tapeworm Triloculatum geeceearelensis, and the unidentified species in the genera Anthobothrium, Paraorygmatobothrium, and Phoreiobothrium.
The Finetooth shark is Viviparous. Litters range from 2 to 6 pups, and are born every other year. Gestation is 12 months long; spermatozeugma occurs, but for how long it is unknown.
In the northwestern Atlantic, mating occurs from early May to early June and the young are born at around the same time. Newborn Finetooth sharks measure between 19–25 inches long. Shallow bays and estuaries, such as Bull’s Bay in South Carolina, serve as critical nursery areas for newborns and juveniles.
Female Finetooth sharks grow much more slowly and to a larger ultimate size than males.
The maximum lifespan of the Finetooth shark has been estimated to be at least 9 years for males and 14 years for females.
Behavioral Traits, Sensing and Intelligence: Adult and juvenile Finetooth sharks form large schools. These sharks are very energetic. Males to bite females to hold on during mating.
Speed: The Finetooth sharks does swim fast with a lot of energy.
Finetooth Shark Future and Conservation: Finetooth sharks are used for human consumption fresh or dried and salted. Other than off the southeastern United States, the Finetooth shark is of little commercial importance: it is small and can be found in water that is too shallow for most commercial and recreational fisheries, and is generally too fast-swimming to be caught by shrimp trawlers. Small numbers are taken incidentally by floating longlines and on hook-and-line. This species is susceptible to overfishing due to its low reproductive rate, and to habitat degradation due to its inshore habits. Here in Florida, land-based shark fisherman catches the Finetooth shark from shore. We are working hard to put a stop to land-based shark fishing here in Florida. Considerable numbers of Finetooth sharks are caught in drift gillnets operated by the shark fishery off southeastern United States.
Finetooth Shark Recorded Attacks on Humans: The Finetooth shark has never attacked a human, and is not a potential threat. However, if caught, especially in a gill net, it will thrash around and rightfully defend itself. So watch your hands, you may be bitten.