>>229
でしょ is a colloquial form of でしょう and has a meaning quite similar to だろ, which is also an informal word.
As for katakana in wikipedia's articles, it's because the words you're referring to are scientific terms. More specifically, katakana is often used in the nomenclature of creatures and plants to differentiate scientific definitions from loose meanings used in daily conversation.
For example, felidae is ネコ科, not 猫科 or ねこ科. So, if a feline has a very odd looking, maybe you don't refer as 猫 though it belongs to ネコ科.
On a side note: There are also many scientific terms written in kanji such as 哺乳綱 (Mammalia), but most of the time they are recognized as technical terms.