The urphish as replaced its ancestor the swimming urchip. It has continued in its streamline shape. So much so its back fin has re-evolved. The shell has gotten smaller and form a primitive dorsal fin. Two of the tentacles have developed a membrane between them and work like pectoral fins. The other two latch on to their prey. They use their sharp hollow beak to pierce their prey and them will suck out the inside after they inject acidic saliva. Due to these adaptations has caused it to spread all along the western coasts of Wright.