Hammerhead, Force sensitives of the sea world.

DESCRIPTION

The nine known species of hammerhead range from 0.9 to 6 m long (3 to 20 feet). All the species have a projection on each side of the head that gives it a resemblance to a flattened hammer. The shark's eyes and nostrils are at the tips of the extensions.

The hammer shape of the head was once thought to help sharks get food, aiding in close-quarters maneuverability and allowing the shark to turn sharply without losing stability. However, it was found that the special design of its vertebrae allowed it to make the turns correctly, more than its head. But as a wing the hammer would also provide lift; hammerheads are one of the most negatively buoyant of sharks. Like all sharks, hammerhead have echolocation sensory pores called ampullae of Lorenzini. By distributing the receptors over a wider area, hammerheads can sweep for prey more effectively. These sharks have been able to detect an electrical signal of half a billionth of a volt. The hammer-shaped head also gives these sharks larger nasal tracts, increasing the chance of finding a particle in the water by at least 10 times as against the ability of other 'classical' sharks.

Wider spacing between sensory organs better enables an organism to detect gradients and therefore the location of a gradient source such as food or a mate. The peculiar head of this shark can be thought of as analogous to the antennae of an insect.

The hammerheads are aggressive predators, eating fish, rays, cephalopods, and crustaceans. They are found in warmer waters along coastlines and continental shelves. They can also be spotted in the Gulf of Mexico along the Western coast of Florida. They are often caught by fisherman however released back into the wild, as they are protected species.

Hammerheads have disproportionately small mouths and seem to do a lot of bottom-hunting. They are also known to form schools during the day, sometimes in groups of over 100. In the evening, like other sharks, they become solitary hunters.

Hammerheads are notably one of the few creatures in the animal kingdom to acquire a tan from prolonged exposure to sunlight, a feature shared by pigs and humans. Tanning occurs when a hammerhead is in shallow waters or close to the surface for long periods.

The ampullae of Lorenzini are special sensing organs, forming a network of jelly-filled canals found on elasmobranchs (sharks and rays) and Chimaera. Each ampulla consists of a jelly-filled canal opening to the surface by a pore in the skin and ending blindly in a cluster of small pockets full of special jelly. The ampullae are mostly clustered into groups inside the body, each cluster having ampullae connecting with different parts of the skin, but preserving a left-right symmetry. The canal lengths vary from animal to animal, but the electroreceptor pores' distribution is approximately species-specific. The ampullae pores are plainly visible as dark spots in the skin. They provide sharks and rays with a sixth sense capable of detecting electro-magnetic fields as well as temperature gradients.These organs help sharks sense electric fields in the water. They were discovered by Stephan Lorenzini in the late 1700s.

Electro-magnetic field sensing ability

The ampullae detects electric fields in the water, or more precisely the difference between the voltage at the skin pore and the voltage at the base of the electroreceptor cells. A positive pore stimulus would decrease the rate of nerve activity coming from the electroreceptor cells and a negative pore stimulus would increase the rate of nerve activity coming from the electroreceptor cells.

Sharks may be more sensitive to electric fields than any other animal, with a threshold of sensitivity as low as 5 nV/cm. That is 5/1,000,000,000 of a volt measured in a centimeter-long ampulla. Since all living creatures produce an electrical field in muscle contractions, it is easy to imagine the shark may pick up weak electrical stimuli from the muscle contractions of animals, particularly prey, on the other hand, the electrochemical fields generated by paralyzed prey were sufficient to elicit a feeding attack from sharks and rays in experimental tanks, therefore muscle contractions are not necessary to attract the animals. Shark and rays can locate prey buried in the sand, or DC electric dipoles simulating the main feature of the electric field of a prey buried in the sand.

The electric fields produced by oceanic currents moving in the magnetic field of the earth are of the same order of magnitude as the electric fields that sharks and rays are capable of sensing. Therefore, sharks and rays may orient to the electric fields of oceanic currents, and use other sources of electric fields in the ocean for local orientation. Additionally, the electric field they induce in their bodies when swimming in the magnetic field of the earth may enable them to sense their magnetic heading.


Temperature sensing ability

Early in the 20th century the purpose of the ampullae was not clearly understood and electrophysiological experiments suggest a sensibility to temperature, mechanical pressure and maybe salinity. It was not until 1960 that the ampullae was clearly identified as a receptor organ specialized in sensing electric fields. The ampullae may also allow the shark to detect changes in water temperature. Each ampulla is a bundle of sensory cells containing multiple nerve fibres. These fibres are enclosed in a gel-filled tubule which has a direct opening to the surface through a pore. The gel is a glycoprotein based substance with the same resistivity of seawater, and it has electrical properties similar to a semiconductor, allowing it to essentially transduce temperature changes into an electrical signal that the shark may use to detect temperature gradients.

Ok, I used to do alot of sea fishing from shore, I can assure you, fish have many 'powers'

Also, I keep tropical fish, they are great barometers, and have many other wonderful little quirks.

It has also been shown that prior to under water earthquakes, volcanos and other perilous natural events, many fish and other creatures will vacate the area well before any seemingly detectable events occur.

I have thought for a long time that we humans do not give the natural world all the credit that is due.

Dogs are another. How is it, all the dogs my sister has had, have always known to be real gentle when nr my legs? no one has taught them or trained them, and on one occasion, one of the dogs 'knew' i was heading for a diabetic low blood sugar, before I felt symptoms.

There was recently on UK tv a great Nigel Marvin series called shark island, all about hammerheads, I wonder if this is where some of your material came from as they made many new discoveries on this show.

All my life I have looked at sharks in wonder and awe, they are beautiful creatures, I totally understand why they are revered as gods. I have spent hours in sea life centres just watching the sharks. I have also been lucky enough to catch tope and dogfish, small sand sharks in UK waters, even the little ones are amazing.

BTW... another recent study has proven the size of a fish's swim bladder directly affects its level of hearing.

If you are interested in fish, i can post a link to a magazine that has a great website and sends excellent newsletters with all sorts like this

they also have a major blind spot. If you place yourself right in the middle of their head, the electormagnetic signals are bounced right through as if you are not there, but reflection of something blocking the way. I learned this when I scuba diveded at an oil rig last summer. Not a fun experience, but interesting to say the least.

I had learned the basics of shark biology during my Zoology and Marine Biology classes, but we didn't get this indepth about the Hammerhead. Thank you for sharing this information with us. I am majoring in Biology and am fascinated by how animals have adapted to and overcome the challenges of their environments.

And as far as animals being 'more', I am constantly amazed by my family's cats. They each have their own distinct personalities and always know what's going on in the house. How people can discount all animals as 'dumb creatures' I don't know. They are often more in touch with the energies of the world than we are....

even my fish in my tanks have very individual habits/personalities, sure there is a general pattern of 'common' behaviours for example in a tetra shoal, but the individuals all have their own quirks

here is the link

http://www.practicalfishkeeping.co.uk/

lots of useful and excellent scientific information there. I also learned alot fro my brief work placement at a wildlife trust, where they bred endangered species, sadly no fish, but repltile, birds n mammals galore.

If I hadnt have chosen environmental science degree, I would have done the marine biology one at Bangor, North wales., i love all this sort of thing, it never ceases to amaze.

What fascinated me about the Hammerhead was it was said to have seven senses, and was claimed to be the most efficient killer in the animal world. Also when the Great White closes its eyes on attack it can still see clearly with its senses. They even compared this to the Jedi in the Films.

OK, read up on Blind cave Tetra

its all done through the lateral line, almost a multi frequency radar/sonar/thermo/sonic/barometric etc ete device in one package

all fish are amazing creatures, im sure most share sharks abilities to some degree

Bump. For Master Sarus and Sr. Kira

Thank you Father Hans the Hammerhead has always been one of my favorite sharks. Thanks for the info

May the Force be with you

new theory on the hammer if you didnt already know

they annually meet at a specific point where two ocean currents collide - basically its so turbulent at this point - very few fish manage to cope in it - ie stay in one position for too long

its thought the hammer head shape allows some degree of aquadynamics or indeed up/downforce - enabling the sharks to remain in an area long enough to find a mate and breed

Personally - in not convinced - very few fish (except man made abominations) have a shape that doesnt suit their environment (ie water) and most sharks are extremly powerful swimmers in their own right - great whites, porbeagal, mako, tope, bull, all goo examples of strong oceanic sharks - hell - if a great white can cope with the cape horn currents - im sure it could cope in the same mess as the hammerheads tolerate.

Maybe its just one of those freaks of nature that works for no other reason than it can

We too have plenty of body parts that are useless

MTFBWY - A