Can you imagine rivers, lakes or great oceans without fishes? These animals make grand water bodies livelier. However, millions of years ago, there were no fishes in waters!
Scientists who study fossils to place various prehistoric organisms say that the first fish probably came into existence about 500,000,000 years ago, in the Ordovician Period.
The ancient fishes did not have the kind of mouth fishes have now. They were jawless. They just had a small opening as their mouths, with which they ate only tiny organisms found hidden in the mud. These fishes gradually evolved and spread in number to other bodies of water later. During the Devonian Period, fishes were the most common animals in the planet. Therefore, the period is also known as the age of fishes.
Jawless fishes and fishes with jaws became abundant during this time. Ostracoderms were a group of jawless fishes. However, they soon became extinct.
The jawless fishes died out because fishes with jaws were evolving. Early fishes with jaws are called Placoderms. Do you know that the sharks and bony fishes of the present day come from Devonian Placoderms?
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