Koichi can look at a fish's tail and tell you what kind it is based on that alone.
Without tails, birds would have difficulty landing.
Why do you think the custom of shortening dog’s tails started?
The kanji and the word are exactly the same. That means they share meanings as well.
Since this word is made up of a single kanji, it should use the kun'yomi reading. You haven't learned this reading yet though, so here's a mnemonic to help you:
You look down and you've sprouted a tail! You're so shocked that all you can say is "Oh. (お) Oh okay..." This your life now. A life with a tail.