I reread the part of book 5 where they all morph ants. There is definitely a deeper meaning KA was trying to communicate there, possibly the central message of the series:
The ant's mind erupted inside my own!
There was no fear. None.
There was no hunger.
There was no ... no self. No me.
No me.
No ...
<Listen to me! You are going the wrong way! The ant minds are controlling you!>
Close now. The scent of food was stronger.
Mandibles working. We would touch the carcass. We would judge its size. If it was too big to
carry, we would hack it into smaller pieces and carry the chunks to the colony.
<You have to take control! You have to fight! You have to get a grip!>
Or enemies would come. And kill.
Suddenly, I realized that there had been something ... a sound. Yes, not a smell. Not a smell.
Not a feel.
<You are humans! You are humans. Listen to me. You are not ants. Fight it! Fight it!>
Yes, not a smell or a feel. In my head.
My.
Me.
Marco.
<AHHH!> I screamed inside my own head. Tobias said later that it scared him half to death.
He thought I was being killed.
That wasn't it at all. I had been reborn.
<AHHHH! AHHHH! AHHHHH!>
<What's the matter?> Tobias cried.
<I ... I ... I lost myself,> I said. <I was gone. I was lost. I didn't even exist.>
<Hive,> Cassie said, sounding shattered. <They are social insects. Part of a colony. A hive. I
should have guessed. I should have known. Ax is right. Each of us is only a part. Like a
single cell within a human body.>
One by one, we said yes. It was only partly true. Yes, I had gained control over the ant mind.
But it was still there. It was powerful in a totally new way. It was the simplicity that made it
hard. The ant was a piece of a computer. Just a tiny switch, a part of a much bigger creature -
the colony.
But it was not fear I felt from the ant brain. It was not capable of emotion, or anything like
emotion. It simply knew that there were enemies close by.
And it knew that it would come down, sooner or later, to kill, or be killed.
Lots of people think only humans fight wars. That only humans are murderous. Let me tell
you something - compared to ants, human beings are full of nothing but peace, love, and
understanding.
A month or so after the experience with the ants, I picked up a book about ants. The author
said, "If ants had nuclear weapons they would probably end the world in a week."
He's wrong. It wouldn't take them that long.
Full quote, from The Earth Dwellers: Adventures in the Land of Ants:
Ants in particular are possibly the most aggressive and warlike of all animals. They far exceed human beings in organized nastiness; our species is by comparison gentle and sweet-tempered. The foreign policy aim of ants can be summed up as follows: restless aggression, territorial conquest, and genocidal annihilation of neighbouring colonies, wherever possible. If ants had nuclear weapons, they would probably end the world in a week.
Ants are only mindless slaves, a part of something much larger than themselves, as KA describes them. Does that description sound familiar?
It's the simplicity of ants that makes them so warlike and deadly. That's the source of the evil that KA places at the center of the Animorphs universe.
The foreign policy of the ants is the same as the foreign policy of the Yeerks. The Yeerk Empire is an ant colony. Yeerks are referred to by their rank and number. Identity isn't important, the rank and number of the individual may change to suit the needs of the Empire, and the original name is rarely mentioned. Whereas just about every Animorphs book begins with the narrator declaring his or her name.
This is why the series ends with the Animorphs fighting The One. KA didn't pull this villain out of nowhere at the end because she ran out of ideas, that force was the underlying evil throughout the whole series, and the Animorphs will always fight it.
<You are humans! You are humans. Listen to me. You are not ants. Fight it! Fight it!> The Animorphs series is meant to convey an anti-war message. Not pacifism, because KA uses the Pemalites to show that simplistic pacifism doesn't work. The solution Animorphs points to is that understanding the other side is the more effective answer. "Peace, love, and understanding" are the qualities KA uses to contrast humans with ants. Ants, in their mindless simplicity, are "possibly the most warlike and aggressive of all animals." To ants, everyone who is different is an enemy. Kill or be killed.
Seventeen thousand. Living creatures. Think-
ing creatures. How could I give this order? Even
for victory. Even to save Rachel. How could I give
this kind of order?
They could have stayed home, I thought. No
one had asked them to come to Earth. Not my
fault. Not my fault, theirs.
No more than they deserved.
Aliens. Parasites. Subhuman.
<Flush them,> I said.