10 Animal Idioms and Their Meanings | Grammar Newsletter - English Grammar Newsletter

My wife, who teaches English to international students (from Japan, Korea, Saudi Arabia, Columbia and elsewhere), might find the idiom definitions here useful. But I found them interesting, enlightening and perhaps useful one of these days.

One thing that the article reminded me, though, is that idioms can be confusing to people who don't understand their metaphorical meaning. So ponder if using one of them will aid your particular audience.  Of course, some idioms can also be so common as to be boring and unnoticed -- in other words, cliches to avoid.

This site begins:

Humans and animals have a long history. The behavior of animals and their interactions in modern-day situations have inspired a variety of zoological idioms and expressions that are applied to people and everyday circumstances. 

Blogger Victoria describes these idioms:

• An Alley Cat
• A Paper Tiger
• As Poor as a Church Mouse
• To Make a Mountain Out of a Molehill
• To Serve as a Guinea Pig
• To Back the Wrong Horse
• The Black Sheep of the Family
• To Cast Pearls Before Swine
• A Cat Gets One’s Tongue
• To Have a Tiger by the Tail