A bio-engineered creature that is usually found near large bodies of fresh water such as lakes, rivers, and marshes. Researchers believe that, since no records or remains of these creatures can be found that date further back than a few decades ago, they mutated from a different type of creature, and soon became the dominant species.

Seasoned travelers have learned that if Yarva are near by, there is usually a body of drinkable water close at hand as well.