Shorefishes of the Greater Caribbean online information system

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Species: Sphyrna tiburo, Bonnethead shark, Common bonnethead shark, the Bonnethead

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hammer narrow, front semicircular, no indentations
front teeth sharp, rear teeth molars

Sphyrna tiburo (Linnaeus, 1758)

Bonnethead shark, Common bonnethead shark

A small hammerhead shark with a very narrow, rounded shovel-shaped head, without the prominent lateral-blade extensions of other hammerheads; width of head 19-25% of TL; front margin of head broadly convex and without indentations; teeth smooth; front teeth blade-like, with 1 short, stout point, rear teeth are enlarged keeled molars; lower front teeth straight, upper front teeth oblique & deeply notched on rear side;  five gill slits, last one over pectoral; first dorsal fin moderately large and erect, its rear margin concave, its origin behind the pectoral rear tip, its free rear tip not reaching over pelvic fins; second dorsal fin base about half length of anal fin base; origin of second dorsal fin above middle of anal fin; anal fin rear edge shallowly concave; transverse pit above tail base crescent shaped, a pit below tail base; tail fin strongly asymmetrical, notched under tip of top lobe, large lower lobe.

Grey or grey brown on back and sides, whitish below; sometimes small dark spots on back.

Maximum size about 150 cm, 10.8 kg; size at birth 35-40 cm.

A common inshore hammerhead ranging into shallow estuaries.

From the intertidal zone to at least 80 m depth.

W Atlantic and E Pacific; the eastern USA to Brazil.

Note: the east Pacific form is sometimes recognized as a separate species, S vespertina.


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Salinity
  • Brackish
  • Marine
  • Freshwater
Inshore/Offshore
  • Inshore
  • Inshore Only
Water Column Position
  • Bottom
  • Mid Water
  • Near Bottom
  • Bottom + water column
Habitat
  • Sand & gravel
  • Water column
  • Soft bottom (mud/sand/gravel/beach/estuary/mangrove/seagrass)
  • Freshwater
  • Estuary
  • Mud
FishBase Habitat
  • Demersal
Feeding Group
  • Data
  • Omnivore
Diet
  • Octopus/squid/cuttlefish
  • Bony fishes
  • Benthic macroalgae/seagrasses
  • Sessile crustacea
  • Data
  • Mobile benthic crustacea (shrimps/crabs)
Egg Type
  • No pelagic phase
  • No pelagic larva
  • Live birth
Global Endemism
  • New world (East Pacific + West Atlantic)
  • Transisthmian (East Pacific + Atlantic of Central America)
  • Greater Caribbean non-endemic
Regional Endemism
  • Continent
  • GC non-endemic
  • Also in Brazil
  • Continent + Island (s)
  • Extends North of GC
  • Island (s)
  • Extends South of GC
  • Extends N + S of GC
Residency
  • Resident
Climate Zone
  • Subtropical (23-35N, Florida / Carolinas / Bermuda)
  • Tropical (10-23N, Nicaragua / Cuba)
  • Temperate (>35N)
  • Equatorial (0-10N, Costa Rica / Venezuela)
IUCN Red List
  • Least concern
  • Listed
CITES
  • Not listed
Depth Range Max
  • 80
Depth Range Min
  • 0
Length Max
  • 150