Shark in captivity at a waterfront aquarium in Bournemouth, UK. Sharks have keen olfactory senses, with some species able to detect as little as one part per million blood in seawater. They are even more attracted to the chemicals found in the gut of many species, and often linger near or in sewage outfalls. Some species, such as Nurse Sharks, have external barbels that greatly increase their ability to sense prey. Shark eyes are similar to the eyes of other vertebrates, including similar lenses, corneas and retinas, though their eyesight is well adapted to their marine environment. Some sharks have stronger nocturnal adaptations, allowing them to see in dark conditions, and some have nictitating membranes to protect the eyes during predation. Sharks generally rely on their superior sense of smell to find prey, but once they are close they also use the lateral lines running along their sides to sense movement in the water and also employ special sensory pores on their heads to detect electrical pulses created by the muscles of prey. Their teeth are not attached to the jaw, but embedded in their flesh, and in many species are constantly replaced throughout the shark's life. The lower teeth are primarily used for holding prey, while the top are used for cutting into it.
© 2004 onwards by Dr Himanshu Tyagi. All the photographs in this blog are copyright protected and can not be reproduced or stored in any medium without the written permission from Dr Hiamnshu Tyagi.
