When we see dolphins we act with all out five senses, we see them, hear them, if we want to we can lick them and taste them, of course you would not want to, but you can. You can also feel them with your hands, and you can sniff them if you like, even though they don't have much of a smell. Well just as we sense dolphins, they do too, only in a different manner. Dolphins do not have all the same senses as we humans do, for example they have very good eye sight, but no sense of smell. Sensory biologist tried to understand these things and during their research they made an interesting discovery about the Guiana dolphin.
Since Dolphins do not have a sense of smell the Guiana dolphin can detect electric fields, this is what replaces the sense of smell and helps them find many fish to eat. Scientists think that these dolphins are benthic eaters, this means they look for food on the sea floor. For most benthic eaters it is hard to find food dow there because animas make clouds of dirt and sand while looking for food and it gets mixed up with the water and then the water in no longer transparent and becomes opaque and then it is hard for the animals to see their pray. Finding food with being able to sense electric fields makes it easier for these animas to get around.
This sense comes from their snouts. "Living organisms generate electric fields. The beat of the heart, the work of a cell, and the pump of gills all produce tiny but measurable electric fields. In 1992, scientists even measured the electric field produced by small goldfish" -http://www.sciencenewsforkids.org/2011/08/dolphin-dimples-detect-electricity/ What ever you do makes an electric field, when you talk, when you quite and when your brain is working everything creates and electric field. And animals also create electric fields in many natural ways. Scientist though that the dolphins electro sense may have something to do with the small dimples on their snout called vibrissal (pronounced "vy-BRIS-uhl") crypt. Scientist though of what its function must be so they tested it. They tested on two Guiana dolphins from Münster, Germany. First though, the scientists took tissue from a 29-year old dolphins snout who died of natural causes. The vibrissal looked familiar under a microscope. Scientists found out that they looked similar to sensors used by other animal to detect electric fields. Also they found nerve fibers running into the pits and that is a sure sign of electrical activity. Next the group of scientists studying this dolphin tested out on a live 28-year old dolphin named Paco. They tested him to see if he would recognize an electric field. they trained him to do a few things such as to swim close to the device that created small electrical fields in the water. They also trained him to swim away from the device to a treat he liked (a fish probably). When the scientists would flip the switch Paco would be trained to swim away if he notice any changes in the electrical field. When there was no electrical field he would stay put and now swim closer or farther away. When they put plastic over Pacos snout he did not react to the electrical field, because his vibrissals we covered and therefor he could not sense the electrical field. After these tests the scientist working with Paco confirmed that he used his snout to detect any amount of electrical fields.
the dolphins in this image are a couple of Guiana dolphins swimming in the Atlantic ocean and Caribbean sea. 
