The paddlefish once thrived in lakes and rivers throughout North America and Asia. Four of the six species are now extinct, with the last two close behind. It feeds by opening its mouth to a width more than double that of its body to filter zooplankton, its only food. But what is most amazing about this fish is the method it uses to locate its prey. Tens of thousands of receptors detect minute electrical impulses that even tell the paddlefish the direction the plankton are going. The paddlefish can actually sense the impulses from the zooplankton's individual appendages. Similar in method to sharks and rays, but far more developed, the paddlefish' ability means it does not even need eyesight. It has hardly changed in almost 300 million years!