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Hammerhead sharks , otherwise known as Sphyrna lewini, are a species of sharks known for their hammer-shaped lateral extension of the head. The width of a head of the hammerhead shark is typically 30% of the total length. These sharks have wide-set eyes which enable them to have a better visual range than most other shark species.
FAST FACTS:
just like us humans, hammerheads school during the day! . . . but they only feed at night!
instead of water, the hammerhead's liver is filled with oil, giving it enough buoyancy to float instead of swim!
hammerheads have sensory organs spread throughout their wide hammerhead, otherwise known as the rostrum, which help them to scan and locate food!
their sensory organs also can detect electronic signals as small as a half-billionth of a volt!
hammerheads travel in schools containing up to 500 sharks!
found in warm tropical waters, such as the area known as Cocos Island in Costa Rica!
Turn around, jump on your left foot three times, then go watch the video.
. . . Hold your horses, what exactly are they using to hunt for prey?!
THEY ARE USING PHYSICS!
The Hammerhead Itself
The easiest way to know if you're looking at a hammerhead shark (as opposed to, say, a great white or nurse shark) is - go figure - their hammer-shaped head. This feature not only distinguishes the species but also increases the sharks senses in many different ways:
1. Increases maneuvering ability
2. Heightens senses linked to vision, smell, and pressure detection
3. Senses minute variations in magnetic fields
The Basics
Most people know the basic aesthetics of the hammerhead shark - the hammer-shaped head (hence its name) with wideset eyes. The placement of their eyes allow these sharks to have a greater field of vision than most sharks. The flat and wide shape of the rostrum also allows for a greater surface area for the special sensory organs to be spread across.
In chemistry, we learned that having a greater surface area allows a reaction to occur at a greater speed than a small surface area. This is relatable to the hammerhead shark and it's sensory organs: the more space there is for the sensory organs to spread out on, the more electric and magnetic fields the sharks can detect, and the more accurately it can accomplish this task.
Sarah Palin is really smart. She knows EVERYTHING.
She is doing a live video streaming session at SJAM!
SERIOUSLY. The Background proves it.
Please listen to her as she tells you about Hammerhead sharks.
Getting into the Details
Specialized sensory organs are spread across the rostrum ("hammer" head), allowing the shark to seek out food more effectively. One specific group of sensory organs, called the ampullae of Lorenzini, allow the sharks to pick up the electric fields of their prey. Salt makes the ocean water electrically conductive, thus creating electric fields.
This especially comes in handy when juvenile hammerheads are trying to seek out sting rays (a favorite of the younger sharks), which are usually buried under the sand and therefore invisible to the naked eye. By using the sensory receptors on their rostrum, hammerheads can pick up on the sting rays electric field and enjoy a delicious meal.
Adult hammerheads on the other hand mainly consume fish and squid, so don't need their sensory organs for feeding. In this case, it it believed that the ampullae of Lorenzini help to navigate the sharks through the ocean.
When ocean crust is secreted, it creates weak north and south magnetization bands. Seamounts (underwater mountains which don't reach the water's surface), such as this one on Cocos Island (above), have natural dipoles because of their volcanic nature. The hardening of basalt (extrusive volcanic rock) on the seamounts creates magnetic valleys and ridges, which allow the hammerheads to pick up extremely small magnetic field variations (from the order of 100 to 300 nanoteslas, nT, to on overall field of 50,000 nT).
As you now know, the sensory organs are spread across the rostrum, which means that the smallest changes in intensity can be sensed - the right and left sides of the hammerhead will get different magnetic field readings. This is what geophysicists call a natural gradiometer that is able to detect different intensities, thus allowing the hammerhead shark to stay at one site during the day, then find another site at night to feed from. During the day, the sharks will rest at the seamounts, and then can use the north-south bands during the night to get food. Basically, they use the dipoles as landmarks and the north-south bands as roads, similar to how people use buidings as their landmarks to travel and use the streets as a means to get to their destination.
Practice Question
Now that you've learned all this neat information about sharks, let's apply it to physics!
Some Hammerhead sharks have been experimentally trained to expect a food reward when a magnetic field is turned on in their environment. Inside one of these experimental tanks is one hammerhead shark. This tank is cylindrical, 8m in diameter and has 200 turns of wire wrapped around it. The magnetic field is created within the tank when the coiled wire carries a current of 2.0 A. The magnetic permeability constant is 4πx10^-7. What is the magnetic field strength within the tank?
How would you go about solving this?
1. First, you need an equation
Magnetic field on a circular loop equation:
2. Then, apply the equation
In this situation:
N=200
I=2.0 A
R=4m
μo=4πx10^-7
So,
B= (200)(4πx10^-7)(2) / 2(4)
= 6.3x10^-5
Therefore the magnetic field strength within the tank is 6.3x10-5 T
**The units of B is tesla (T). T=N/Am, Tesla = Newtons (N) over Amperese (A) x meter (m)
"Dr. Krause: This would have been easier... if we used sharks, that laid eggs. Dr. Preston King: Easier? Maybe. But the giant hammerhead isn't like other sharks. It's the pinnacle of shark evolution. Nurtures its young in placenta. What's a Great White? It's a machine - swims and eats. Doesn't think, like the sphyrna mokarran. The sphyrna is far more advanced. Much more capable of being genetically integrated with the human race. "
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LOL!
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