English as a Second Language/the word obligate
I am a student from Taiwan. Yesterday I was reading a magazine article and came up with one word which I do not know its precise meaning. Quoted below was one paragraph from National Geographic Magazine, December 2015: As animal species have evolved, they’ve sometimes lost tastes that their ancestors possessed. Cats and many other OBLIGATE carnivores, which eat only meat, can no longer detect sugars. (When cats lap milk, they’re responding to something else—probably fat.) Most whales and dolphins, which swallow prey whole, have lost almost all taste receptors.
My question is, what does the word "obligate" in this paragraph mean? This word is related to responsibility, right? But,the meaning responsible does not seem to fit in the context. Could you please help me? Thank you .
An obligate carnivore is an animal that must eat the tissue of other animals in order to thrive. Obligate carnivores may eat other foods, such as vegetables, grains, or fruit, but they have to eat meat as the main source of their nutrients.
I hope this helps.