See this discussion

http://forums.gardenweb.com/discussions/1747477/how-do-i-plant-elephants-ear

I notice in the link and elsewhere there are two common genus, Colocasia. and Alocasia . Apparently the latter will thrive in wet margins.

I had a quick browse of that link supplied above and unfortunately there is a tremendous amount of misinformation in it. The problem is that when you use the term "Elephant Ears" in relation to plants it's almost as vague as using the word "tree". The term is used for any aroid with roughly heart shaped leaves (there is also an "Elephant Ear" tree, Acacia dunnii). But even for only aroids that makes many thousands of different plants in several genera, Alocasia, Colocasia, Caladium, Xanthosoma, Cyrtosperma, Urospatha, Typhonodorum, etc., etc., and requiring a lot of different growing conditions. The most likely common one if it's described for ponds would be a species of Colocasia. The only way to find out for sure is to ask the supplier (if they know, that is) or get the plant and post photos and hope that someone can identify it.