Some, however, have a gaudy color on their back or underside throughout the year. This can occur in both sexes or sometimes only in the male, especially during courtship. Species that live underground and ones lacking pigment have a white or pink coloration. With the exception of two species in the Onychodactylus family of an Asian genus, salamanders lack nails. The two species in the Onychodactylus family have a horny sheath, similar to nails, that turns black during the mating season.
Many salamanders are nocturnal.
Here's one of those interesting tidbits I promised you. Bet you were just dying to know that one weren't you. Now onto the skeletal system. Some parts of the skull begin as cartilage and then turn to bone later on in growth. The rest of the skull is made up of membranous bones, or bones that start out as bones.