Are skills that an animal companion has ranks in considered class skills

Question

For the purpose of getting a +3 to an animal companions skills, are skills that an animal companion invests in considered class skills?

The rules as written state the following:

This lists the animal's total skill ranks. Animal companions can assign skill ranks to any skill listed under Animal Skills. If an animal companion increases its Intelligence to 10 or higher, it gains bonus skill ranks as normal. Animal companions with an Intelligence of 3 or higher can purchase ranks in any skill. An animal companion cannot have more ranks in a skill than it has Hit Dice.

Animal companions can have ranks in any of the following skills:

Acrobatics* (Dex), Climb* (Str), Escape Artist (Dex), Fly* (Dex), Intimidate (Cha), Perception* (Wis), Stealth* (Dex), Survival (Wis), and Swim* (Str).

All of the skills marked with an (*) are class skills for animal companions. Animal companions with an Intelligence of 3 or higher can put ranks into any skill.

But unfortunately they don't mention anything about whether or not investing in a skill gives them a +3 rank bonus, similar to how a PC would receive a bonus by placing a rank in a class skill.

Answer 1

Yes, they would for the skills that are class skills (Acrobatics, Climb, Fly, Perception, Stealth, and Swim).

http://paizo.com/pathfinderRPG/prd/usingSkills.html

Each skill rank grants a +1 bonus on checks made using that skill. When you make a skill check, you roll 1d20 and then add your ranks and the appropriate ability score modifier to the result of this check. If the skill you're using is a class skill (and you have invested ranks into that skill), you gain a +3 bonus on the check. If you are not trained in the skill (and if the skill may be used untrained), you may still attempt the skill, but you use only the bonus (or penalty) provided by the associated ability score modifier to modify the check. Skills can be further modified by a wide variety of sources—by your race, by a class ability, by equipment, by spell effects or magic items, and so on. See Table: Skill Check Bonuses for a summary of skill check bonuses.