For a long time, cetaceans have been thought to have either an extremely limited sense of smell or none at all. This is largely because the olfactory bulb (a sensory centre responsible for the perception of smell in the brain) is reduced in baleen whales and completely absent in their toothed counterparts. It has been noted that, as foetuses, baleen whales possess the olfactory structures (nerves and bulbs) necessary for smell, but toothed whales do not, even at this early stage.
However, the fairly recent dissection and research of a whale has indicated that some whales still possess hardware that links the brain and the nose, as well as protein receptors that are necessary if any sort of smelling is to be done. This particular specimen was a bowhead whale, which is of the baleen group of cetaceans.
Other whale species have still been found to be in possession of their Jacobson’s organ, formally known as the vomeronasal organ. This organ is usually used by animals to detect pheromones, but is also responsible for the ability to smell food once it is in the mouth.
This is in line with the theory that some researchers hold that baleen whales seem to be able to sniff out krill in the water. This idea has been discarded as impossible for some time, but may now be a possibility in light of this recent research and its subsequent findings.
Because whales possess a number of other senses that are particularly well developed (such as hearing and echolocation), it is not as important for them to be able to smell as it is for terrestrial animals, for example. For animals like the dog, elephant or rhino, being able to smell warns of danger, helps in tracking and aids in finding food. However, whales use their other sensory organs for these uses, as they are more effective in the water.
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