First dorsal finVery tall and curved like a sickle.
Second dorsal finThe smaller of the two fins on the back.
Pectoral finOne of a pair, low on each side behind the head.
Pelvic finOne of a pair on the underside of the body.
Anal finA single fin under the body, just before the tail.
Caudal fin (tail)The tail fin, in two unequal parts.
The head from below 7
Cephalofoil (the hammer)The hammer. It is the wide, flat front of the head.
EyeOne at each end of the hammer.
NostrilA hammerhead smells with its large nostrils.
NotchA shallow notch at the middle of the front edge.
Pores (ampullae of Lorenzini)Small pores that sense other animals' electric fields.
MouthSmall for a shark, and set under the head.
TeethTriangular, with edges like a saw.
How this list was compiled: Every name checked on 2026-10-01 and kept only where two independent sources use it. (1) The Florida Museum of Natural History, Discover Fishes species profile of the great hammerhead, https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/sphyrna-mokarran/ (cephalofoil with a nearly straight front margin and a shallow notch in the center; small pores, the ampullae of Lorenzini, along the underside of the head; tall curved first dorsal fin, second dorsal fin, pectoral fin, pelvic fins, anal fin, asymmetrical caudal fin; triangular, strongly serrated teeth; mouth). (2) Wikipedia, text only: Hammerhead shark and Great hammerhead, https://en.wikipedia.org/wiki/Hammerhead_shark and https://en.wikipedia.org/wiki/Great_hammerhead (the cephalofoil; an eye on each end; the small mouth centered underneath; the ampullae of Lorenzini; the indentations of the front margin; first and second dorsal fins, pectoral, pelvic and anal fins; triangular serrated teeth). (3) The University of Michigan's Animal Diversity Web accounts of the great and scalloped hammerheads, https://animaldiversity.org/accounts/Sphyrna_mokarran/ and https://animaldiversity.org/accounts/Sphyrna_lewini/ (cephalofoil, wide-set eyes, large nostrils, ampullae of Lorenzini on the underside of the hammer, a forked caudal fin with unequal lobes). (4) The Australian Museum's page on the great hammerhead, https://australian.museum/learn/animals/fishes/great-hammerhead-sphyrna-mokarran/ (eyes at the ends of the hammer-shaped head; nostrils; ampullae of Lorenzini). Eye rests on sources 2, 3 and 4; nostril on 3 and 4; caudal fin on 1 and 3; the others on 1 and 2. Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry; nothing traced. Licence: own work
How it works
The body parts of a hammerhead shark are those of other sharks, except for the head. The first drawing has the six kinds of fin. The second turns the head over to show the hammer from below.
Read the full guide
Fins from the side
Numbers 1 to 6 are fins. Two dorsal fins stand on the back, the first tall and curved like a sickle. The pectoral and pelvic fins come in pairs, the anal fin is single, and the caudal fin is the tail.
The hammer from below
Numbers 7 to 13 are on the head. The hammer is called the cephalofoil. It has an eye at each end, nostrils, a notch in the middle of its front edge and small pores on its underside. The mouth and its teeth lie behind it.
From the side only the end of the hammer shows, with the eye in it.
The drawing follows a great hammerhead, whose front edge is nearly straight.
Questions and answers
What is the head of a hammerhead shark called?
The cephalofoil. It is wide and flat, with an eye at each end. The mouth is small for a shark and sits underneath, in the center.
Where are a hammerhead shark's eyes?
One at each end of the hammer. Set there, they let the shark see above and below itself at all times.
Why do hammerhead sharks have a hammer-shaped head?
Scientists have suggested several uses. The wide head spreads out the eyes and the pores that sense electric fields, which helps the shark find stingrays buried in sand, and it may help the shark turn quickly.
What are the ampullae of Lorenzini?
Small pores that all sharks and rays have. On a hammerhead they are spread over the underside of the head, and they sense the weak electric fields of other animals.