oceany: Hammerhead shark

Evidence: 100 • authority: 72

The hammerhead sharks are a group of sharks that form the family Sphyrnidae, named for the unusual and distinctive form of their heads, which are flattened and laterally extended into a cephalofoil (a T-shape or "hammer"). The shark's eyes are placed one on each end of this T-shaped structure, with their small mouths directly centered and underneath. Most hammerhead species are placed in the genus Sphyrna, while the winghead shark is placed in its own genus, Eusphyra. Many different—but not necessarily mutually exclusive—functions have been postulated for the cephalofoil, including sensory reception, manoeuvering, and prey manipulation. The cephalofoil gives the shark superior binocular vis…

Evidence: 67 • authority: 92

Sphyrna alleni sp. nov., a new hammerhead shark (Carcharhiniformes, Sphyrnidae) from the Caribbean and the Southwest Atlantic.. Hammerhead sharks (Family Sphyrnidae) comprise a monophyletic Miocene radiation of carcharhiniform sharks characterized by their laterally expanded and dorsoventrally compressed head ('cephalofoil'). The bonnethead shark (Sphyrna tiburo) is currently described as a single amphi-American hammerhead species composed of the subspecies Sphyrna tiburo tiburo in the Western Atlantic Ocean (WA) and S. tiburo vespertina in the Eastern Pacific Ocean (EP). Variation in mitochondrial DNA and cephalofoil shape suggest a species complex, with S. tiburo occurring in the U.S., Me…

Evidence: 54 • authority: 88

The electrosensorial pore system of the cephalofoil in the four most common species of hammerhead shark (Elasmobranchii: Sphyrnidae) from the Southwestern Atlantic. The laterally expanded head is the principal character distinguishing hammerhead sharks, and its morphology is important for interpreting their ontogeny and species diversity. Because their head shape changes during its ontogeny, it is vital to evaluate it in order to establish other taxonomical characteristics to correctly identify Sphyrna species. This study examines the distribution of electrosensorial pore regions on the ventral surface of the cephalofoil (VSC) in Sphyrna lewini , S. tiburo , S. tudes and S. zygaena from the…

Evidence: 80 • authority: 72

The smooth hammerhead (Sphyrna zygaena) is a species of hammerhead shark, and part of the family Sphyrnidae. This species is named "smooth hammerhead" because of the distinctive shape of the head, which is flattened and laterally extended into a hammer shape (called the "cephalofoil"), without an indentation in the middle of the front margin (hence "smooth"). Unlike other hammerheads, this species prefers temperate waters and occurs worldwide at medium latitudes. In the summer, these sharks migrate towards the poles following cool water masses, sometimes forming schools numbering in the hundreds to thousands. The second-largest hammerhead shark after the great hammerhead shark, the smooth h…

Evidence: 54 • authority: 72

The great hammerhead (Sphyrna mokarran) is the largest species of hammerhead shark, belonging to the family Sphyrnidae, attaining an average length of 4.6 m (15 ft) and reaching a maximum length of 6.2 m (20 ft). It is found around the globe in all the warmer parts of the oceans. The great hammerhead can be distinguished from other hammerheads by the shape of its "hammer" (called the "cephalofoil"), which is wide with an almost straight front margin, its tall, sickle-shaped first dorsal fin, and its strongly falcated pelvic fins. A solitary, strong-swimming apex predator, the great hammerhead feeds on a wide variety of prey ranging from crustaceans and cephalopods, to bony fish, to smaller…

Evidence: 48 • authority: 72

The winghead shark (Eusphyra blochii) is a species of hammerhead shark, and part of the family Sphyrnidae. It is the sole member of the genus Eusphyra. Reaching a length of 1.9 m (6.2 ft), this small brown to gray shark has a slender body with a tall, sickle-shaped first dorsal fin. Its name comes from its exceptionally large "hammer", or cephalofoil, which can be as wide as half of the shark's total length. The function of this structure is unclear, but may relate to the shark's senses. The wide spacing of its eyes grants superb binocular vision, while the extremely long nostrils on the leading margin of the cephalofoil may allow for better detection and tracking of odor trails in the wate…

Evidence: 48 • authority: 92

Global COI meta-analysis reveals ocean-basin genetic structure in Sphyrna lewini.. The scalloped hammerhead shark (Sphyrna lewini) is a circumglobally distributed apex predator clarified as Critically Endangered due to population declines exceeding 80%. Understanding population structure is essential for effective conservation management, yet comprehensive genetic surveys across the species' range remain limited. We conducted a meta-analysis of all publicly available cytochrome oxidase I (COI) sequences for the family Sphyrnidae from the Barcode of Life Database (BOLD), applying a hierarchical analytical approach that examined haplotype clustering patterns across all hammerhead species. Thi…

Evidence: 42 • authority: 72

The scalloped hammerhead (Sphyrna lewini) is a species of hammerhead shark in the family Sphyrnidae. It was originally known as Zygaena lewini. The Greek word sphyrna translates into "hammer" in English, referring to the shape of this shark's head, which is its most distinguishing characteristic. The shark's eyes and nostrils are at the tips of the extensions. It is a fairly large hammerhead, but is still smaller than both the great and smooth hammerheads. This shark is also known as the bronze, kinky-headed, or southern hammerhead. It primarily lives in warm, temperate, and tropical coastal waters all around the globe between latitudes 46°N and 36°S, down to a depth of 500 m (1,600 ft). It…

Evidence: 42 • authority: 80

A Revision of the Hammerhead Sharks (Family Sphyrnidae)

Evidence: 42 • authority: 92

Evolutionary Stability of the Shark Snout: Geometric Morphometrics of Ventral Facial Openings.. Chondrichthyans are among the most ancient vertebrates, and their morphology has enabled adaptation to diverse marine environments. In sharks, the head is the functional center for feeding, respiration, and sensory perception, reflecting a balance between phylogenetic constraints and ecological demands. Striking specializations, such as the cephalofoil of hammerhead sharks or the elongated rostrum of sawsharks, illustrate remarkable adaptations. Most studies on head shape have focused on single species or restricted clades, whereas broader analyses have focused on parts of the skull. We analyzed…

Evidence: 36 • authority: 92

Migratory patterns and seasonal habitat use of great hammerhead sharks (Sphyrna mokarran) in the southeastern United States.. The great hammerhead shark (Sphyrna mokarran) is a highly mobile shark species whose population in the United States declined dramatically through the early 2000s. Their spatial ecology is poorly understood, creating challenges for effective conservation of this enigmatic marine predator. Using acoustic telemetry and network analyses, we describe the movement patterns of 15 mature great hammerhead sharks (207-331.5 cm fork length) primarily within the waters of the southeastern United States from April 2019 to December 2022, including identifying movement corridors,…

Evidence: — • authority: 80

Geometric morphometric analysis of head shape variation in four species of hammerhead sharks (Carcharhiniformes: Sphyrnidae)