The Animorph book series

A few days ago i went to the library and found an interesting book series about a group of people who have special suits allowing them to morph into animals that they have acquired the DNA of. Another thing is that they can only stay in the guise of a certain animal for two hours without being stuck that way. Their main intention ,though, is fighting aliens called Yeerks which are disgusting green-grey slugs. I'd
better not tell you what they can do to humans because it's completely disgusting.
The first of the series that i read was called The Extreme in which the Animorph group find out that the Yeerks have a secret base some where on earth . In the end they destroy the arctic base by morphing into polar bears and charging about like crazy!
They are good books and i recommend them!