Since childhood, many should remember such strange marine life as fish with a saw on their nose. These creatures look frankly strange. At the same time, it is quite obvious that evolution does not endow anything just like that. This raises the question: why do fish need the same saw? The correct answer to this question is actually not as obvious as it might seem at first glance.
In fact, nose saws are found in two separate families of marine life. The first is sawnose sharks. Very ancient marine life that appeared on earth 140 million years ago and today are found in various parts of the world's oceans. These sharks are not very big. The largest individuals grow up to 1.7 meters in length. They feed mainly on molluscs, small fish and crustaceans.
The second family is sawn rays (this is what they are called). This family of marine life is almost 80 million years younger than the sharks mentioned above. Stingrays are noticeably larger, do not swim as deep as sharks and live mainly in warm tropical waters. The sizes of these fish can range from 1.4 to 7 meters. Also, like the sawnose sharks, the stingrays have a hefty bony nose-saw - the rostrum.
In both stingrays and sharks, the rostrum on the nose is needed for two purposes. The first one is quite simple and obvious - it is hunting. With the help of a saw-nose, sharks and rays tan their prey. The fish are willingly used this nose to protect themselves from larger or unnecessarily annoying predators. True, sharks and rays kill marine life due to a strong blow, and not due to teeth. For all the seeming brutality, their purpose is by no means obvious.
The fact is that in addition to the "combat" function, the nose of sharks and rays is also an electromagnetic locator. Fish are essentially living radars. Their body generates an electrical charge that spreads through the water around them through the nose. The very teeth on the nose-saw are just needed for better propagation of electric waves, with the help of which spear hunters can find their prey in absolute darkness, as well as in very muddy water.
Continuing the topic, read about why scientists from different parts of the world want to get to Meinipilgyno - a tiny village in Chukotka.