Bonnethead Shark

ANIMAL:
Bonnethead Shark    Sphyrna tiburo

Type of Animal:
Hammerhead Shark

Habitat:
Tropical/subtropical/temperate waters-shallow estuaries/bays/channels w/ mud/sand/seagrass bottoms, surf zones, intertidal zones, reef habitats, found in inshore, coastal, continental, & insular shelf areas as deep as 260 ft.

Location(s):
In W Atlantic, ranges from Rhode Island westwards through Gulf of Mexico & Caribbean through N & E coast of S America far south as most of Brazil. In Pacific, found from far S California to NW Peru. Prefer water temps of at least 70 F, making them migratory.

Appearance:
Broad smooth spade-like head, smallest member of Sphyrna genus, gray to gray-brown above & lighter on underside, females have broadly rounded head, males have distinct bulges along anterior margin of hammerhead, some individuals have dark spots.

Food/Diet:
Crabs, shrimp, clams, octopus, small fish, bivalves, snails, seagrasses, isopods, barnacles, squid, krill

Status in Wild:
Endangered 

Conservation:
Breeding in aquariums, marine parks, & zoos

Lifestyle:
Schools of 3-15 sharks, sometimes aggregations of up to 100

Additional Info:

Called:
Male
Female
Young-Pup
Group-School
 
Weight:
Male: 13 lbs
Female: 22 lbs
Young: 3 lbs

Gestation:
5-6 months 

Life Span:
12 years

Body Length:
Male: 2.5 ft
Female: 3 ft
Young: 1 ft

Tail Length:
Male: 1.5 ft
Female: 2 ft

Main predators of adults are larger sharks & crocodiles. Larger fish, birds, & pinnipeds prey on young.
 
These sharks viviparous (giving birth to live young).
 
During development, uterus separates into compartments housing each embryo & yolk sac.
 
One of shortest gestation periods of any shark.
 
Like all sharks, males have claspers used in mating & courtship.
 
Like many sharks, they have rows of teeth in place to replace any that have been lost.
 
Sometimes called shovelhead shark.
 
Females congregate in shallow areas to give birth.
 
Only known sharks to exhibit sexual dimorphism of head.
 
They tend to be very active & fast-moving.
 
Hammer shape of head allows them to scan larger areas of bottom than other sharks.

Endangered due to overfishing, coastal development, shark-finning, pollution, & low reproductive rate.

Fun Fact(s):
They excrete unique cerebrospinal fluid believed to let other animals know it’s around.
 
By far most common hammerhead sharks in captivity due to small size, docile nature, & ability to mix w/ other animal species.
 
They have nearly 360-degree vision & excellent depth perception.
 
Unique head shape may give them added lift, enabling them to make sharper turns.
 
Parthenogenesis (development of embryo from unfertilized egg) has occurred on rare occasions in this species.
 
Attacks on humans extremely rare w/ only 1 recorded unprovoked attack.

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