I do know that an imp is like a tiny demon thing. But this is not the case.
A species i want to start up. They aren't just going to be called Imps. In fact i don't know what else to call them besides Imps.
These small-ish creatures are about the size of a large goldfish or a guinea pig. These endothermic creatures have a problem of keeping their body temps down, and in turn of their bodies being composed of some flammable elements they combust if not cooled. A rather sad ending for a creature, that is why they hang around cool areas rather than warm to keep their body temps in check.
They are lizard like four legged animals with slender bodies. They have simmilar antennae as of cawhgels or pulbs. But with a bio luminescent organ at the end. Imps are nocturnal creatures, and have rather good eye sight. Along with good eye's, they have an organ that is simmilar to what snakes have which allows the Imp to detect body temps.
The organ is located in he snout. This organ is connected to their brain and relays the info into their sight when their active, since they hunt at night in cold conditions they have an upper adavtage to find prey. But this is a disadvantage as well, since too much heat could throw off the im (think of it as looking into really good bight vision equipment, then suddenly some one flashes a bright light into the optics)
Imps are neither reptiles nore mammals since the Imps share traits from both categories. Their mouths are lined with teeth that can easily cut meat but can also chew tough materials. They do have neurotoxin stored into the teeth produced by two poison glands, suprisingly its very lethal to small animals or even smaller but strong enough to paralyze larger prey or even cause severe heart problems.
Their skin is smooth and leathery. Their bones share similar qualities towards cartilage, so if they get crushed their bones wont shatter.
The reason why i call this species Imps is because of their luminescent bodies with either a red or blue glow during activity. This glow suprisingly helps them distinguish prey from their environment when hunting. The tip of their tails glow aswell, but is used to ward off predators (they curl their tail up like how a scorpion shows its hostility).
Imps have no fur nor hair, but just has a bare leathery hide that protects the softer skin from dangers. Once an Imp grows too big, it sheds its hide like a reptile and has a new larger hide that thickens when it comes into contact to the cold air. The hide houses special organs that contain the bio luminous cells that make tyem glow blue or red. But its only on their sides, a region on their head, and tail.
Imps make their home in areas that have anclimate of 30°F or below 0°F. During they day they rest under snow, ice, or any thing that will shelter tyem from heat since they can not control their body temp from skyrocketing causing them to combust. Imps could take refuge in water, but they can't swim nor breathe underwater.
Edit: came up with a name, Snow Imps.