Has anyone ever seen a mud guppy?

I think it's a lizard.
Answers:
I think you mean a mud puppy. They are also called water dogs. Both terms refer to the larval form of a salamander, much as a tadpole is the larval form of a frog. Although they have the same general shape as a lizard, they are considered amphibians. The difference between the two being the presence of scales in lizard and the lack of in amphibians. Lizards tend to be terrestrial and suited for desert life, while amphibians must spend at least part of their lives in water and are more "slimy" instead of scalely. I used to catch mud puppies and keep them as pets when I was a kid. They are interesting to observe during their metamorphosis from water bound creature to adult salamander. They look like their adult self except for the presence of finger-like gills with red feather-like tissue lining their lower margins. As maturity approaches, the gills are slowly absorbed and eventually disappear. Some mud puppies do not actually become salamanders but instead reach sexual maturity before metamorphosis. This is called paedomorphosis and its cause is not clearly understood. I think the water dogs that do this are called axolotls- They get really big compared to the others. Mud puppies are commonly cannibals and occasionally the cannibalistic larve undergo pronounced morphological changes. Normal larve of the species I played with would grow to be about 5 inches long and about 1 inch across the head, but occasionally there would be one that was over a foot long and 2 1/2 to 3 inches wide at the head!

---

It's called a mud puppy and you can find them occasionally at pet stores for your aquarium. I have two of them.
(by the way... they are not lizards, which are reptiles, they are salamanders, which are amphibians)
Here's a pic of one if you wanted to see it:
http://encarta.msn.com/media_461553560_7...