Question: Which two groups of marine animals also have freshwater species living in the Amazon River?
A) Dolphins and B) Stingrays
Summary: Originally, the Amazon River started as an inland sea, similar to the Caspian Sea in central Asia. Over time, animal species like dolphins and stingrays were able to adapt from their salt water roots to the capability of living in the Amazon’s now fresh waters. There are two kinds of dolphins and more than twenty species of stingrays that now live in this river system.
Main source: Monga Bay, Rhett Butler; http://rainforests.mongabay.com/amazon/
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