Appearance
On average, males measure 1.5 to 1.8 m and weigh about 29 kg when they attain sexual maturity, whereas the larger females measure 2.5 m and weigh 80 kg on average at sexual maturity. The maximum length of the scalloped hammerhead is 4.3 m and the maximum weight 152.4 kg , per FishBase. A female caught off of Miami was found to have measured 3.26 m and reportedly weighed 200 kg , though was in a gravid state at that point.These sharks have a very high metabolic rate, governing behavior in acquiring food. These sharks occupy tertiary trophic levels. The scalloped hammerhead shark, like many other species, uses the shore as a breeding ground. Due to high metabolic rates, young scalloped hammerhead sharks need a lot of food, or they will starve.
Distribution
The scalloped hammerhead is a coastal pelagic species; it occurs over continental and insular shelves and in nearby deeper water. It is found in warm temperate and tropical waters, worldwide from 46°N to 36°S. It can be found down to depths over 500 m , but is most often found above 25 m . During the day, they are more often found close to shore, and at night, they hunt further offshore. Adults are found alone, in pairs, or in small schools, while young sharks occur in larger schools.
Behavior
Scalloped hammerhead sharks have a homing behavior to navigate in the ocean. They move in the night and use the environment as a map, similar to a human reading a topographical map. By experimentation in tagging these sharks, one could test for any guidance in a shark’s movement. These sharks use a point-to-point type of school swimming, and do not favor going too deep where temperature changes hitchhike with current speed and directional change.The scalloped hammerhead uses deep water to survive as safety and feeding. Although they have high metabolic rates, they have a tendency to be sedentary and allow currents to carry them as they swim. As a result, this causes the scalloped hammerhead to be selective where they swim and the depth at which they tend to stay. The scalloped hammerhead has a tendency to eat cephalopods.
Habitat
The scalloped hammerhead is a coastal pelagic species; it occurs over continental and insular shelves and in nearby deeper water. It is found in warm temperate and tropical waters, worldwide from 46°N to 36°S. It can be found down to depths over 500 m , but is most often found above 25 m . During the day, they are more often found close to shore, and at night, they hunt further offshore. Adults are found alone, in pairs, or in small schools, while young sharks occur in larger schools.
Reproduction
The gestation period is reported to be around 12 months. Compared to other species, the scalloped hammerhead produces large litters, and this is most likely due to high infant mortality. Like most sharks, parental care is not seen. Nursery grounds for this species are predictable and repeated over the years, and they are faithful to their natal sites. Their natal sites still cause high infant mortality; a lack of resources prevents all the young from surviving. As a result, only the fittest grow to maturity. Also, should a population get depleted, it recovers through reproduction and not immigration. This species do not seem to attack each other even in periods of starvation. In addition, scalloped hammerheads have migratory behaviors. As a result, deprivation results from migration as well as young growth. While the Taiwan scalloped hammerheads seem to have an earlier maturity rate, it is still reported to be slow to mature.
Food
This shark feeds primarily on fish such as sardines, mackerel, and herring, and occasionally on cephalopods such as squid and octopus. Larger specimens may also feed on smaller species of shark such as the blacktip reef shark, ''Carcharhinus melanopterus''.References:
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