HAMMER HEAD SHARKS

What Is A Hammerhead Shark?

-Members of the Sphyrnidae family-Includes eight species: Scalloped

Bonnethead, Winghead Shark, Scalloped Hammerhead, Scoophead Shark, Great Hammerhead, Bonnethead Shark, Golden Hammerhead and Smooth Hammerhead.

-Set apart from other sharks by their hammer shaped head

Habitat

Hammerhead sharks are found in long coasts in water up to depths of 300m and also in shallow coastal areas

Habitat Continued…-Migrate to cooler water during summer months

frequently in large masses-Found in lagoons and continental shelves-Large gatherings found in bodies of water such as

Hawaii, South Africa, Australia - studies concluded they are highly social and communicate through body movement including rituals such as shaking the head and pushing other with their bodies

Feeding Information-Prey on many different species such as fish and other types of sharks

-Stingray is most valued food source; tail spine is even consumed

-Invertebrate prey: crabs, squid, octopus, lobsters

-Bony fish: groupers, catfish, flatfish

-Great hammerheads have been reported of eating their own species-Feeds at dusk along floor of sea

(Flying cloud. 2008)

(Antonio, 2008)

Body of a Hammerhead-Hammerhead has several distinctive features-“cephlafoil”, meaning two wide flattened

expansions that resemble shape of hammer-Hammer shaped extensions made up of connective

tissue and supported by skeloton -Hammer shaped head varies from each type of

hammerhead including great, scalloped, and smooth

-Round eyes located on far regions of hammer head-very far apart

-Lateral expansions also include nostrils-Dorsal fins located on shark varies in size and

direction of point, all very large-Brown to light grey on dorsal side and white

underside-Strong triangular teeth, 2-3 teeth in upper jaw and

1-3 teeth located in lower jaw used most frequently, 17 teeth surrounding main upper and lower jaw teeth

-Denticles cover the skin and are close together diamond shaped and smooth

-Can weigh over 500 pounds and 20 feet in length with the great hammerhead being the largest in size

Anatomy of A Hammer Head

(Stapley, 2011)

Predatory Success-Hammer heads use their body form as an advantage when

capturing live prey -They can control the angle of attack that their head pins down

prey-Highly maneuverable and can use whole body and weight to

hold onto prey- can bat down and restrain with just their head -This plays a role in the capture of sting rays which are animals

that swim on an angle-Very quick and efficient at holding prey in place and then

consuming it -Nostrils and eyes (36 degree view of surroundings)being spread

out plays a vital role in capturing of prey; it allows hammerheads to see and smell their prey quicker then other types of sharks would; receptive to electric impulses emitted by other animals

-Eats about 1% to 10% of its total body weight per week

Advantages to “Hammer head”

-Optic nerves in a hammerhead’s brain are reached through smell that enters each nostril individually

-Hammerheads can determine direction of smell by paying close attention to which nostril the smell hits first since they are so spread apart

-Nostrils spread apart allows them to detect a smell at a greater distance away from them compared to other sharks

Reproduction-Slow reproduction rate-Frequently mate close to surface of water-Yolk-sac placenta sustained in uterus -Live birth known as viviparity -Relies on nutrition to feed unborn pup-Birth occurs after 11 months in spring and

summer- occurs in Northern Hemisphere-6-42 pups are born in a litter Head shape of pup changes are they grow

Specific importance to humans

Hammerhead sharks are highly valued for their fins, their meat is consumed by humans and they provide liver oil for vitamins

Conservation and Endangerment

Classified in large coastal species group-most vulnerable to overfishing

Usually not a specific target to fishers but often die when they are caught by gillnet or nets

Currently considered to be endangered by the World Conservation Union

Under threat due to shark finning operations Populations are vulnerable to fishers because of

slow reproduction rate According to the International Union

Conservation of Nature, the great hammerhead species has declined in numbers by 50% in the last 10 years

Most prized fins are coming from the already endangered area of the Atlantic

Interesting facts

-Hammerhead sharks can get a sun tan from swimming close to waters surface for an extended amount of time- dorsal side will become darker when increased exposure to sun

-Some members of the shark family including hammerheads exert up to 8,000 pounds of force per square inch when biting their prey

-These specific sharks are wanted to make Asian fin soup that can cost between 20 and 1,000 dollars a bowl

Image References

Powerdinky. Baby Hammerhead. 19 Feb. 2008. Flickr.com. Web. 20 Nov. 2011http://www.flickr.com/x/t/0098009/photos/24027902@N08/2277915531/

Pertersbar. Hammer from Cocos Island, Costa Rica. 3 Jan 2010. Flickr.com. Web. 20 Nov. 2011

http://www.flickr.com/x/t/0098009/photos/barrypeters/4242623174/

Seamore. The depths.9 March 2009. Flickr.com. Web. 20 Nov. 2011http://www.flickr.com/x/t/0093009/photos/seamoor/3341036032/

*Cris*. Hammerhead Shark. 12 June 2007. Flickr.com. Web. 20 Nov. 2011 http://www.flickr.com/x/t/0094009/photos/cristiano_deana/542916788/

MaestroBen. Hammerhead. 13 Feb 2007. Flickr.com. Web. 20 Nov. 2011http://www.flickr.com/x/t/0098009/photos/maestroben/389503682/

Erik Charlton. Hammerhead. 12 Oct 2008. Flickr.com. Web. 20 Nov. 2011.

Image References Continued…

http://www.flickr.com/x/t/0095009/photos/erikcharlton/2935553971/

Flying Cloud. Sea World Sting Ray. 13 July 2008. Flickr.com. Web. 20. Nov. 2011.

http://www.flickr.com/photos/flying_cloud/2666292417/.

Antonio, Charlie V. Giant Crab at Manilla Ocean Park Philippines. 19 April 2008. Flickr.com. Web . 20 Nov. 2011. http://www.flickr.com/x/t/0099009/photos/charlimages/2424279935/ .

Text ReferencesBester, Cathleen. “Great Hammerhead.” Florida Museum of Natural History. FLMH Icthyology

Department, 2011. Web. 7 Oct. 2011http://www.flmnh.ufl.edu/fish/gallery/descript/greathammerhead.html

Galloway, Evan. “Sharks Follow Their Nose.” Today’s Science. Facts On File News Services, July 2010. Web. 7 Oct 2011. http:://www.2facts.com/article/s1800090

Maddalena, Alessandro and Buttigieg, Alex. “The Social Lives of Hammerheads.” WorldandI.com, June 2006. Web. 1 Nov 2011.http://www.worldandi.com/subscribers/feature_detail.asp?num=25044

Martin, Aiden. “Sandy Plains: No Place to Hide. Great Hammerhead Shark.” ReefQuest Centre for Shark Research. Biology of Sharks and Rays, n.d. Web. 1 Nov 2011. http://www.elasmo-research.org/education/ecology/sandy-gt_hammerhead.htm.

Murray, Loiuse. “Endangered Great Hammerhead Sharks Tracked on North Atlantic.” Earth times. Feb. 2011. Web. 7 Oct 2011.http://www.earthtimes.org/nature/endangered-great-hammerhead-sharks-tracked -north-atlantic/340/.

Text References Continued

Plessis, Amelia Du. “Sharks: The Hammerhead Sharks.” Sharks.org. 2011. Web. 7 Oct 2011. http://www.sharks.org.za/hammerhead-shark.html.

SeaWorld Parks & Entertainment. “Sharks and Rays-Diet and Eating Habits.” SeaWorld/Busch Gardens: Animals, 2011. Web. 7 Oct. 2011.http://www.seaworld.org/about-us/index.html.