Some Spanish expressions with animals

When we learn a new language we not only want to communicate, we want to communicate with fluency and be able to show ourselves as we are, without having obstacles that prevent us from expressing our being.
In order to be able to express ourselves with complete fluency, we have to understand and use the expressions that that language has and that differentiates it pragmatically from other languages, and even from a dialect or geographical area.
Idiomatic expressions are expressions that do not have the literal meaning of what is said, they are also widely used in the language and the speakers use them a lot in their discourses, especially in spoken discourse and even more in colloquial speech, although not always they are exclusive to that record.
Let's see some idiomatic expressions with animals and their meaning:
"Ser un burro." It is used with two meanings. The first is said of someone who is very stubborn, the second is used to express that someone is not very intelligent.
Maria is very burra, until she has not managed to be the plant director has not stopped.
María es muy burra, hasta que ha conseguido ser directora no ha parado.
"Estar como sardinas en lata." When we are very tight in one place.
I do not intend to enter that disco to be like sardines in a can, I want to be able to dance.
No voy a entrar en esa discoteca para estar como sardinas en lata, yo quiero bailar.
"Ser un pez gordo." It is said of someone who is very important.
Ramón is a big shot in the office, if you want something, ask him.
Ramón es un pez gordo en la oficina, si quieres algo, pídeselo a él.
"Ser un rata" It is said of people who are very stingy.
Your brother is a rat, he never invites, we always invite him to him.
Tu hermano es un rata, nunca invita, nosotros siempre le invitamos a él.
"Estar en época de vacas flacas/gordas." If we say fat cows we refer to a time of abundance, if they are lean times we speak of a time of scarcity.
Elena is very cautious and, although now in her company she is full of fat cows, she is prepared for the lean cows.
Elena es muy precavida y aunque su empresa está de vacas gordas, ella está preparada para las vacas flacas
"Lágrimas de cocodrilo." We use it to say that someone does not really cry, that is, their tears or their grief is false.
When you want to go out and you can not always loose crocodile tears.
Cuando quieres salir y yo no siempre lloras lágrimas de cocodrilo.
"Cortar el bacalao" It is said of the person who has power in a place.
Here is Lola who cuts the cod, commands more than the boss.
Aquí Lola es la que corta el bacalao, manda más que el jefe.
What is the one you like? Do you know any other idiomatic expression with animals