What is mud lizard?

As an AI language model, I cannot claim if there is any such animal that goes by the name of 'mud lizard'. However, if you are referring to a mudskippers or mudpuppies, here is some information:

Mudskippers are a type of fish that belongs to the subfamily Oxudercinae. They are commonly found in the Indo-Pacific region and are known for their ability to breathe air and move on land. Mudskippers have elongated bodies and strong fins that allow them to crawl over mud and sand. They also have a specialized organ that allows them to extract oxygen from the air, similar to how humans breathe.

On the other hand, mudpuppies (Necturus maculosus) are a type of salamander that lives in fresh water. They are commonly found in streams, rivers, and lakes in North America. They are adapted to living in muddy habitats and can be identified by their robust, four-legged body, bushy gills, and flat head. Mudpuppies are nocturnal and feed on a range of prey, including fish, crayfish, and insects.