Change animation with a script

Hi, I’m trying to make a script which makes a creature evolve.
The new creature will have a new animation, so, how can I change the animation?

That’s the script:

using UnityEngine;
using System.Collections;

public class Evolution : MonoBehaviour {
	public int soglia;
	public Sprite primafase;
	public Sprite secondafase;
	public Sprite terzafase;
	MouseButton tocchi;

	// Use this for initialization
	void Start () {
		tocchi = gameObject.GetComponent<MouseButton> ();
	// Update is called once per frame
	void Update () {
	    if (tocchi.tocchi < soglia) {
			gameObject.GetComponent<SpriteRenderer> ().sprite = primafase;
		if(tocchi.tocchi >= soglia){
			gameObject.GetComponent<SpriteRenderer>().sprite = secondafase;

How can I do this? Can I change the state of the animation controller or something like that?

(Sorry for my bad english)

You need to access the object’s Animation component assign the right Animation Controller to it as well, so it corresponds to the new Sprite you assigned to the SpriteRenderer. This allows you to play all the animations stored in the new AnimationController.