An ottsel is a creature combination of an otter and weasel. They have Redish-Orange fur with golden yellow bellies. Those seen in the series are even capable of speech and a respectable level of intelligence. Although the Precursors are in fact ottsels, it is unknown if all ottsels are Precursors. They appear in every Jak game to date, though in Jak and Daxter: The Precursor Legacy, Jak II,Daxter (game) and Jak and Daxter: The Lost Frontier Daxter is the only ottsel to make an appearance.

Source : http://jakanddaxter.wikia.com/wiki/Ottsel