hammerhead shark

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Related to Sphyrnidae: Squalidae, Isuridae, Mobulidae, Alopiidae, Pseudotriakidae

hammerhead shark,

active, surface-living shark, genus Sphyrina. Its curious head has lateral projections resembling the crossbar of a T, and its eyes and ears are located in the outer tips of the projections. This arrangement apparently gives the shark excellent binocular vision, and helps them see above, below, and behind as well as in front. It has been suggested that the extension of the head in the plane of the pectoral fins may give the fish increased lift, but there is no evidence that hammerheads are better swimmers than other sharks. Found in inshore, brackish water, hammerheads are both predators and scavengers. They feed on a variety of fishes including skates, rays, and other hammerheads, and large hammerheads have been known to attack and eat humans without provocation. The largest species is the widely distributed great hammerhead, Sphyrina mokarran, which typically reaches 15 ft (4.6 m) in length; the distance between its eyes may be as much as 3 ft (90 cm). The common hammerhead, S. zygaena, is found in all tropical waters, summering as far N as Newfoundland. It may reach a length of 12 ft (3.7 m). The bonnet, or shovelhead, shark is a small, harmless hammerhead found in the W Atlantic from Brazil to Massachusetts. It reaches a length of 5 ft (150 cm) and its lateral lobes are much shorter than in other species, giving the head a rounded appearance. There are several other species distributed throughout tropical and temperate oceans. Hammerhead sharks are classified in the phylum ChordataChordata
, phylum of animals having a notochord, or dorsal stiffening rod, as the chief internal skeletal support at some stage of their development. Most chordates are vertebrates (animals with backbones), but the phylum also includes some small marine invertebrate animals.
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, subphylum Vertebrata, class Chondrichthyes, order Selachii, family Sphyrnidae.
References in periodicals archive ?
Notably the Carcharhiniformes were strongly supported as monophyletic, as were the families Sphyrnidae and Triakidae.
Unidentified shark 5 Negaprion brevirostris Lemon shark Sphyrnidae, Hammerhead sharks 6 Sphyrna mokarran Great hammerhead 7 Sphyrna tiburo Bonnethead Dasyatidae, Stingrays 8 Dasyatis spp.
1 Nurse 3 3 Spinner 2 69 Dusky 2 4 Smalltail 2 8 Sphyrnidae 2 9 Frequency of % frequency Species occurence of occurence Atlantic sharpnose 732 12.