poliformismo

<?php

class Animal {
    public function Andar(){
        echo "O animal andou";
    }

    public function Correr(){
        echo "O animal correu";
    }
}

class Cavalo extends Animal {

    public function Andar(){
        $this->Correr();
    }
}

$animal = new Cavalo();
$animal->Andar();

?>