- Common Name
- bonnethead shark
- Genus Species
- Sphyrna tiburo
- Species is a smaller member of the hammerhead family with a unique narrow shovel-shaped head. Head is noticeably more rounded in appearance than with other members of Sphyrnidae. Additionally, the head lacks indentations on its anterior edge. Its dentition includes enlarged, molariform posterior teeth. The posterior edge of the first dorsal occurs prior to the anterior edge of the pelvic origins. The upper lobe of the caudal fin is noticeably larger than the lower lobe.
Male: External claspers located on the far underside of the body – forward of the caudal fin – distinguish males.
- 150 cm (4.9 ft) max;
- 11 kg (24.3 lbs) max
- Primarily crustaceans (i.e. crabs, shrimp, isopods, and even barnacles); also bivalves, octopi and small fish
- Species is viviparous with a yolk-sac placenta. Within Florida waters, observations suggest that there is either a spring and autumn mating season or that there is a year-round mating season. Within Brazilian waters, observations suggest that the mating season occurs in the spring.
Litter Size: 4 to 16 pups
- Sexual Maturity
- Male: 52 to 75 cm (20 to 30 in.)
Female: 84 cm (33 in.) or less
- Life Span
- Approximately 12 years
- Western Atlantic: Rhode Island (seasonally) and North Carolina to the Caribbean and southern Brazil
Eastern Pacific: southern California to Ecuador
- This species is abundant within inshore, coastal, continental and insular shelf areas within its range. They are commonly found in estuaries, shallow bays and channels, mud and sand flats, and reef habitats. They typically occur at depths of 10–25 meters (33 to 82 ft); however, species may be found at depths of 80 meters (260 ft) or better. Additionally, species is known to exploit the shallower surf and intertidal zones.
- Global: Global population is unknown, but species is abundant through range
- IUCN: Not listed
CITES: Not listed
USFWS: Not included in the U.S. National Marine Fisheries Services (NMFS) management plan of 1993
- Species is typically observed in groups of 3–15. Rarely observed as individuals.
- A six-month behavioral study of a group of ten bonnethead sharks in a semi-natural enclosure documented eighteen unique postures and action patterns – with the group's daily rhythm of activity peaking in the late afternoon. Observations indicated a distinct dominance hierarchy, mitigated in part by individual size and sex.
- For more information about sharks & rays, explore the Sharks & Rays InfoBook.
Ecology and Conservation
Species is commonly taken via small-scale fisheries. Bonnetheads are caught as by-catch in shrimp trawls, and are either considered by-catch or a targeted species when caught via trammel nets, bottom longlines, or hook-and-line. When targeted as a catch species, they are utilized fresh, frozen or dry-salted for human consumption. Additionally, they are processed as fishmeal.
Compagno, Leonard J.V., FAO Species Catalog, Vol. 4 Sharks of the World. United Nations Development Programme, Food and Agriculture Organization of the United Nations, Rome, 1984.