The Truth About
© Nautilus Productions
23 February 2017
SAND TIGER SHARKS:
The Amazing Shark
The shark has developed over hundreds of millions of years into one of the
worlds most perfect predators. It is a highly developed eating machine.
Range of sensory organs:
- Sharks are slightly farsighted and see in color.
Their eyes can function in light ten times dimmer than that of the
human eye because of a shiny reflective pigment called tapetum lucidum
that is also found in cats eyes. Some sharks posses
a nictitating membrane which closes to protect the eye as the shark attacks
prey. In sharks such as the great white the eye rolls upward for protection
just before the shark bites.
- Sharks are attracted to low frequency, pulsing sounds such as
the sounds made by injured or dying fish.
- Lateral Lines
- Series of fluid-filled canals containing hair-like receptors
(similar to the cochlea of the human ear) which extend along the
sides of the head and body. These sense vibration, change in pressure,
movement and sound.
- The sharks nostril can sense blood in the water as
little as one part per million from a mile away. Lemon sharks can
sense fish oil in water one part per 25 million or the equivalent of
just ten drops in an average home swimming pool, Caribbean reef
sharks can sense grouper flesh concentrations as low as one part per
10 billion or the equivalent of one drop in a quarter acre pond.
- Ampullae of Lorenzini
- Receptor cells located at base of canals on sharks snout,
lower jaw and around the eyes. The Ampullae of Lorenzini detect electrical
fields, their direction, and strength. Every living creature gives off an
electrical field which provides a stimulus or homing device for the shark.
Some sharks can detect a change in direction of electrical intensity
five-billionths of a volt per centimeter in a range of 0-8 Hertz.
This sense can also be used to detect changes in the sharks own
bioelectrical field. It is believed that sharks use this sense to detect
changes in the earths magnetic field and for navigation.
Sound - distances of a couple of miles
Smell - distances of several football fields
Lateral line - distances of several football fields
Vision - distances of dozens of feet
Ampullae of Lorenzini - distances of several feet
Touch & Taste - contact
It is thought that the shark uses the strongest sensory stimulus
first and then shifts to whichever sense is stimulated most as it meets its prey.
Text © Beth Bader 1996 (with additions by Rick Allen).