Cipangopaludina chinensis, (Chinese Apple Snail) and Cipangopaludina Japonicus, (Japanese Apple Snail) are two, very similar, species of live bearing (Viviparus) Apple snails. They were introduced to many parts of the US, from Asia, as a way of controlling algea in back yard ponds. They endure cold winters and there for can become established in ponds as far north as parts of Canada.
I have read, they are even used as a food source in some places. I don't think I would try them though. I know that may shock some of you, as I seem to try just about any food :-)
There seems to be a lot of confusion as to identification of these two species. I have looked all over for a picture of each or, I guess I should say, consistant descriptions and pictures. I have found pictures of both types being labeled as the other. All I can tell you is they will feast on algae in your back yard pond. They don't enjoy being indoors in an aquarium due to the (usual) lack of sufficient algal growth. I'm told they will also eat romaine lettuce, but mine don't. I have found mine eating dead tree leaves that have fallen into the pond.
They DO give birth to live young. The eggs are held inside the female (Yes they do have separate sexes), until they are fully developed. I do not know how long this takes. The young then crawl out of the parent and start to feed. They are about the size of a pea when born and appear to have a little line of (what appears to be) hair or fuzz along the spiral. This soon dissapears as they grow.
They don't seem to grow too quickly, but that could change depending on the food supply. They seem to grow to about 2 inches across. Some specimens I have found are a dark brown in color while others are a light brown with a more rounded shape to their shell (possible one of the distinguishing characteristics of the two species). Both have operculms (the hard "cover" for the opening to the shell) for protection.
If any one knows (for sure) how to identify these two species, I would appreciate an email.
The other night,I saw a show on the Food Channel where they were in Vietnam and they were serving these guys! I hate to say it, but they looked good. sorry :-)