Scalloped Hammerhead
Enigmatic sharks that form large schools
The Scalloped Hammerhead (Sphyrna lewini) was originally known as Zygaena lewini, its genus name was later changed to the current name. The Greek word sphyrna translates into “hammer” in English, referring to the shape of this shark’s head or cephalofoil.
Family: Sphyrnidae
Genus: Sphyrna
Species: lewini
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Common Name– Ground Sharks
Common Name– Hammerhead Sharks (Bronze Hammerhead, Kidney-headed shark and many more)
Genus– Sphyrna
Species– lewini
Status: IUCN Red List Endangered (re-evaluated and moving to Critically Endangered)
Average Size and Length: 12 to 14 feet in length, they are larger in size.
Average Weight: They weigh an average of 180 pounds.
Current Rare Mythical Sightings:
Teeth and Jaw: The teeth of the Scalloped Hammerhead are small with smooth or slightly serrated cusps on large bases. The upper jaw contains teeth that are narrow and triangular with the first three nearly symmetrical and erect and the others increasingly oblique towards the corners of the mouth. Near the corners, the teeth become nearly straight along the inner margins and more deeply notched along the outer margins. The lower teeth are more erect and slenderer than that of the upper teeth.
Head: These hammerheads are unique because of the scalloped shape of the front edge of their cephalofoil. Large with a broad-shaped arch that is narrow-bladed.
Dermal Denticles: On the Scalloped Hammerhead shark, the dermal denticles are partially overlapping, exposing the skin. The blades are thin and arched with 3 sharp ridges in small individuals and 4 or 5 on large sharks. These ridges run about half the length of each blade. The axial marginal tooth is longest with short, slender pedicels.
Demographic, Distribution, Habitat, Environment and Range: These sharks are found all over the world, in warm to temperate seas. The Scalloped Hammerhead is found over continental and insular shelves and the surrounding deep water. They range from surface down to about 900 feet. Many of times these sharks are seen inshore, and juveniles remain inshore in estuaries and similar habitats. They are coastal-pelagic and semi-oceanic.
Diet: Other sharks and rays, bony fish and invertebrates.
Aesthetic Identification: Grey to copper or bronze on top. White counter-shading on the belly. They have dusky or black-tipped pectoral fins with a dark blotch on the lower caudal fin lobe. High and slightly longer first dorsal fin. The second dorsal and pelvic fins are low.
Biology and Reproduction: Scalloped Hammerheads are born between a little over 1 foot to 1.8 feet. Females have between 13 and 31 pups. Gestation lasts between 9 and 10 months. Males reach sexual maturity between 2 months and 9 years, and females much later, sometimes 25 years of age.
Behavioral Traits, Sensing and Intelligence: Scalloped Hammerheads are known to have sub populations. These sharks are also large-schooling sharks (juveniles). Adults are usually found by themselves or in twos and sometimes small schools. They migrate seasonally.
Speed: A scalloped hammerhead shark swims at a steady speed of 1.5m/s with its 90cm-cm-wide head perpendicular to the earth’s 53 T magnetic field.
Scalloped Hammerhead Future and Conservation: Their meat and fins have high value, and these sharks are constantly taken illegally (especially Australia).
Scalloped Hammerhead Recorded Attacks on Humans: 21 unprovoked attacks