#PLATYPUS EVOLUTION ALL PLATYPUSES SERIES#

The discovery of yet another curious talent in the platypus, an egg-laying mammal unique to Australia that lives on land but like the otter, feeds in water, is another instance of the phenomenon of convergent evolution. So in both of these not at all kindred night-feeding aquatic species, a sixth sense compensates for the dark. At night in the water, sight is not very useful. Smells travel well in water, as does light, and in some species those senses also are especially acute. It is not surprising that among animals that feed in water, electrical sensitivity should be selected as a more efficient way to hunt. However, electricity is even more efficient in water. Within our own bodies messages move electrically from cell to cell. What is it about platypuses and sharks that selected for a sixth sense, the ability to detect very low-voltage electric fields?ДЄll organic life has an electrical component. Thus it seems clear that while the electroreceptors in platypuses and in sharks function alike in detecting underwater food, they evolved independently in the very different species.Д«ut why did they evolve at all? Most animals find their nourishment by using their eyes, ears or noses. The glands in the bill that are electroreceptors fill the double function of preventing the bill from drying out when it is out of the water. It sleeps and nests on land where it raises its young. The platypus, though comfortable in the water, is only semi-aquatic. The receptors in the platypus have a different evolutionary history. They apparently evolved from the sensory hairs that have the same root as the hairs within the human inner ear that help us retain our equilibrium. These are cells that are found in the head and in lines along the sides of the fish and developed from the acoustic-lateralis system. Sharks, rays and skates carry these receptors in cells called the Ampullae of Lorenzini. Forty years later they had documented both the techniques that dogfish use to detect the electric fields of food fish such as flounder, and the mechanism within the shark that provided the electroreceptors. Zoologists began serious research into the electrical sensitivity of the dogfish, a small shark, in 1934. However, as long ago as 1917 observers had noted that fish, such as the North American catfish, had some electrical sensitivity. Until the publication of this discovery last month in Nature, electroreceptors had been found only in fish such as sharks, skates and rays. This helps them navigate around obstacles, and as predators to hone in on the electrical fields of shrimp, frogs and fishes.ДЄfter the researchers had ascertained that the duckbill is the platypusвЂ™ electroreceptive organ, they discovered with the aid of an electron-microscope that within the large bill the platypus has unique gland duct receptors that connect that gland to the mucous glands on the surface of the platypusвЂ™s skin. The experiments confirmed the researchersвЂ™ suspicions that the platypus is able to detect and respond to very subtle DC and AC electrical fields underwater. The 1 1/2-foot-long mammal searched for food with its eyes, ear canals and nares (nasal openings) closed, and a forefoot always in contact with the wall.

#PLATYPUS EVOLUTION ALL PLATYPUSES SERIES#

They ascertained in a series of four experiments in an artificial pond that the platypusвЂ™s bill could locate both fresh-water shrimp and a miniature 1.5-volt alkaline battery. The electrically sensitive nose that glowed on the mythical reindeer does not exist, but researchers in Australia and West Germany have just discovered an electrical component in the strange duckbill of the platypus. In the trend to make folklore more consistent with our knowledge of real animals, a lead platypus would have more verisimilitude. Perhaps Rudolf should be replaced by a platypus at the head of SantaвЂ™s team.

Platypus evolution all platypuses