Just as humans, viperfish appear to be using two types of photoreceptor cells called rods and cones to see. Both cones and rods contain light-sensitive proteins called opsins. Most vertebrates, however, only have one opsin protein which means they become color-blind in dim light such as the deep ocean. Amazingly, the viperfish has adapted to dark conditions and developed additional proteins, allowing them to see in color in their natural habitat. This can indeed make the difference between life and death in these extremely harsh conditions!