Three hybrids (IMAGE) Stanford University Caption Three hybrid swordtail males displaying varying degrees of melanin invasion, from a small spot -- like spots typically found in sheepshead swordtails (middle) -- to very advanced melanoma (back). Credit Daniel Powell Usage Restrictions Image may only be used with appropriate caption or credit License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.