I use the former term to clarify that I don't ascribe human levels of consciousness to animals, do you?
As for the latter, since you brought it up:
The thing about stuff like "How many Zebras are worth a headache." is that if you think about it enough, you end up at questions like "How many zebras are worth a human?" and then "Are all human lives equal?". When trying to answer such questions things get fuzzy and icky and hard to answer satisfactorily. Then theres versions of those questions where you ask if the answer changes if it's your life being weighed.
Even though it's intuitively obvious that somebodies fleeting minor pain is not worth the cost of losing an entire species of large mammal, talking about "fair trades" with sentient creatures gets weird and frustrating very quickly.[0]
[0]: I personally like the phrase "Infinite Hair" to describe situations like this. (ftp://ftp.trailing-edge.com/pub/rsx11freewarev2/rsx81b/374001/jargon.txt)
No, I do not feel the need to differentiate between the varying consciousness of animals in a discussion such as this. I feel they are owed the basic right to life, freedom from suffering, and an equal right to that which they have an interest in, such as raising their young. For every qualification you could find to rationalize treating animals poorly, aside from the species label we have applied to them, the same qualifications can be found in certain people. That's why it gets fuzzy and icky to start calculating "smart trades" that compromise the rights of some for the good of others.
You should check out Animal Liberation by Peter Singer. I'm not saying I agree with everything he supports, but he makes a bullet proof argument supporting the fact that speciesism is just like any other discrimination, and relies on the same logic as racism, sexism and so on.
As for the latter, since you brought it up:
The thing about stuff like "How many Zebras are worth a headache." is that if you think about it enough, you end up at questions like "How many zebras are worth a human?" and then "Are all human lives equal?". When trying to answer such questions things get fuzzy and icky and hard to answer satisfactorily. Then theres versions of those questions where you ask if the answer changes if it's your life being weighed.
Even though it's intuitively obvious that somebodies fleeting minor pain is not worth the cost of losing an entire species of large mammal, talking about "fair trades" with sentient creatures gets weird and frustrating very quickly.[0]
[0]: I personally like the phrase "Infinite Hair" to describe situations like this. (ftp://ftp.trailing-edge.com/pub/rsx11freewarev2/rsx81b/374001/jargon.txt)