Exploring the Extraordinary Senses of Cetaceans
By zteve t evans
Whales, dolphins and porpoises are marine mammals collectively know as cetaceans. Once many thousands of years ago they were land animals and walked on four legs. For reasons that are unclear they moved from the land into the water and evolved into the marine mammals of today that are at home in their watery environment. To help them survive and flourish in the waters of the world they developed specialised senses.
Special Senses
Cetaceans have special senses and abilities that humans do not possess and they use them to find their way around their environment. Although most of them they see, feel and taste they also have a highly developed sense of hearing and are believed to have an extra sense that humans do not have called geomagnetism. This extra sense enables them to detect the magnetic field of the Earth.
Sight
Different species have different seeing abilities. For example some species of river dolphins are almost blind while many marine cetaceans can see quite well in the water close to the surface or in air. Nevertheless, sight is of limited use in the dark and murky depths of the oceans and sometime the water near the surface can be murky and have poor visibility. To compensate for this many cetaceans have evolved special sensory abilities.
Hearing
Hearing is effective in poor light conditions and is also effective day and night. In such conditions of such poor visibility that are found in the oceans hearing is far more useful and important to them so they have evolved sensitive hearing abilities which they use in conjunction with sounds they make.
Sound travels almost five times faster through water and can be heard over greater distances. Cetaceans no longer have the distinctive ear flaps that other mammals have and their ears are now small holes in their skin behind their eyes. It is also thought that some species may perceive sound through their lower jaw.
Cetaceans have special senses and abilities that humans do not possess and they use them to find their way around their environment. Although most of them they see, feel and taste they also have a highly developed sense of hearing and are believed to have an extra sense that humans do not have called geomagnetism. This extra sense enables them to detect the magnetic field of the Earth.
Sight
Different species have different seeing abilities. For example some species of river dolphins are almost blind while many marine cetaceans can see quite well in the water close to the surface or in air. Nevertheless, sight is of limited use in the dark and murky depths of the oceans and sometime the water near the surface can be murky and have poor visibility. To compensate for this many cetaceans have evolved special sensory abilities.
Hearing
Hearing is effective in poor light conditions and is also effective day and night. In such conditions of such poor visibility that are found in the oceans hearing is far more useful and important to them so they have evolved sensitive hearing abilities which they use in conjunction with sounds they make.
Sound travels almost five times faster through water and can be heard over greater distances. Cetaceans no longer have the distinctive ear flaps that other mammals have and their ears are now small holes in their skin behind their eyes. It is also thought that some species may perceive sound through their lower jaw.
Smell and taste
The senses of smell and taste are similar in that they are both used to detect chemical traces. Even underwater it is possible to use the sense of smell. Sharks are known to be able to smell chemicals in water over long distances. However, toothed whales are thought to have lost their sense of smell and baleen whales have kept only a basic ability. This is possibly because their nostrils or blowholes need to be kept shut when they are diving. They can use taste inside the mouth and also close to the outside of the mouth and is more important to them than smell.
Sensitive skin
The skin of cetaceans is very sensitive and they use their flippers, dorsal fins and beaks to touch one another as a way of greeting, form social bonds and to investigate unknown objects they cone across.
Geomagnetism
To humans geomagnetism is the least understood and known of their senses. It is believed this gives cetaceans the ability read the magnetic field of the Earth like a map helping them to navigate over long distances. It is known that other living creatures, such as bacteria, reptiles, bees, and birds posses this ability. It may be that the human 'sense of direction' may possibly be a limited or basic form of this, but in cetaceans and other creatures it is much more highly developed.
The senses of smell and taste are similar in that they are both used to detect chemical traces. Even underwater it is possible to use the sense of smell. Sharks are known to be able to smell chemicals in water over long distances. However, toothed whales are thought to have lost their sense of smell and baleen whales have kept only a basic ability. This is possibly because their nostrils or blowholes need to be kept shut when they are diving. They can use taste inside the mouth and also close to the outside of the mouth and is more important to them than smell.
Sensitive skin
The skin of cetaceans is very sensitive and they use their flippers, dorsal fins and beaks to touch one another as a way of greeting, form social bonds and to investigate unknown objects they cone across.
Geomagnetism
To humans geomagnetism is the least understood and known of their senses. It is believed this gives cetaceans the ability read the magnetic field of the Earth like a map helping them to navigate over long distances. It is known that other living creatures, such as bacteria, reptiles, bees, and birds posses this ability. It may be that the human 'sense of direction' may possibly be a limited or basic form of this, but in cetaceans and other creatures it is much more highly developed.
Echolocation
Most cetaceans have the ability to build a picture of their underwater surroundings using sound. This remarkable sensory ability is known as echolocation. Other creatures such as cave swiftlets, oil birds, bats, shrews and other land animals have also developed echolocation to hunt in the dark.
The basic principle of echolocation is quite simple. Sounds, usually ultrasonic clicks are emitted and the echoes that are received are used to make sense of the environment and what is in it. In many cetaceans the clicks are thought to be made either in the larynx, or the nasal plugs and focused into a kind of directional beam by the 'melon' which in many species is a bulbous or rounded forehead. The returning sounds may possibly be picked up by the ear holes positioned on both sides of the forehead. Recent research indicates that it more likely to be picked up by the lower jaw and transmitted to the brain.
Although the echolocation system used by cetacean works in a similar way to radar it is different. Radar uses electromagnetic radiation and not sounds. Echolocation uses sound and is a form of sonar. Although humans have sonar systems they are nowhere near as advanced and sophisticated as that of cetaceans. It is believed cetaceans can tell the difference between different types of fish and prey, how fast it is moving, the direction it is moving in, its texture, and possibly its internal structure.
Toothed whales use echolocation to keep track of each other, navigate around obstacles in the water, recognise changes in the sea floor, hunt and locate prey and predators. It is also thought that some cetaceans can emit powerful blasts of sound that can incapacitate or even kill prey. Baleen whales may have some degree of echolocation but it is not believed to be as sophisticated as that of toothed whales.
Extraordinary Sensory Abilities
Different species of cetaceans have developed different and varying degrees of these extraordinary sensory abilities depending on the regions of the world they live in and the kind of food they need to hunt to survive. Their environment and social behaviour may also influence how their senses have developed and are utilised to help them survive in their watery domain.
© 25/07/2014 zteve t evans
Most cetaceans have the ability to build a picture of their underwater surroundings using sound. This remarkable sensory ability is known as echolocation. Other creatures such as cave swiftlets, oil birds, bats, shrews and other land animals have also developed echolocation to hunt in the dark.
The basic principle of echolocation is quite simple. Sounds, usually ultrasonic clicks are emitted and the echoes that are received are used to make sense of the environment and what is in it. In many cetaceans the clicks are thought to be made either in the larynx, or the nasal plugs and focused into a kind of directional beam by the 'melon' which in many species is a bulbous or rounded forehead. The returning sounds may possibly be picked up by the ear holes positioned on both sides of the forehead. Recent research indicates that it more likely to be picked up by the lower jaw and transmitted to the brain.
Although the echolocation system used by cetacean works in a similar way to radar it is different. Radar uses electromagnetic radiation and not sounds. Echolocation uses sound and is a form of sonar. Although humans have sonar systems they are nowhere near as advanced and sophisticated as that of cetaceans. It is believed cetaceans can tell the difference between different types of fish and prey, how fast it is moving, the direction it is moving in, its texture, and possibly its internal structure.
Toothed whales use echolocation to keep track of each other, navigate around obstacles in the water, recognise changes in the sea floor, hunt and locate prey and predators. It is also thought that some cetaceans can emit powerful blasts of sound that can incapacitate or even kill prey. Baleen whales may have some degree of echolocation but it is not believed to be as sophisticated as that of toothed whales.
Extraordinary Sensory Abilities
Different species of cetaceans have developed different and varying degrees of these extraordinary sensory abilities depending on the regions of the world they live in and the kind of food they need to hunt to survive. Their environment and social behaviour may also influence how their senses have developed and are utilised to help them survive in their watery domain.
© 25/07/2014 zteve t evans
References and Attributions''
Copyright 25 July 2014 zteve t evans
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Copyright 25 July 2014 zteve t evans
- The Biology Of Cetaceans | NZETC
- Studying how cetaceans use sound to explore their environment - Peter L. Tyack - PDF. - Biology Dept,Woods Hole Oceanic Institution, Woods Hole, Massachusetts, 02542-1049
- Cetacea - Wikipedia, the free encyclopedia
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