A herd.
Monkeys
a school of fish
a pride
Team
A group of giraffe is called (believe it or not) a tower of giraffe.
Brace yourself.A group of crows is called a murder.Yeah, you read it right. Scary.
Batch
arachnids
Horses are just called "horses" unless they are in a group together. When horses get in a group together, they are then called a "herd".
they are called mustangs. they are the American wild horses. Australian wild horses are called brumbys.
Cool
A dozen horses is usually called a 'string' of horses.