Mammals
The donkey is a vertebrate
Because they have a backbone which determines that it is a vertebrate
A zonkey - a zebra/donkey hybrid - is a vertebrate.
Apart from being a mammal, donkey's have an internal skeleton and a backbone.
Donkeys belong to the class Mammalia. More specifically, they belong to the order Perissodactyla. Within that order, they belong to the family Equidae.
Penguins belong to a vertebrate group called aves.
Starfish are not in a vertebrate group because they do not have vertebrae.
The vertebrate group of rats is the order: Rodentia.
The Pelochelys cantorii vertebrate group is "Reptile."
Amphibians are the vertebrate group that epipedobates tricolor in.
The vertebrate group megadyptes antipodes are in is mammals.
An ambystoma mexicanum is an axolotl, of the vertebrate group amphibians.