The animal kingdom comprises two main groups: vertebrates and invertebrates.
Before reading further about them, watch the funny video my "boss" has especially created on the subject for you.
VERTEBRATES Vertebrate animals have a spinal column (also known as spine) formed by small bones, each called a vertebra.
Man possesses 24 vertebrae: 7 cervical, 12 dorsal and 5 lumbar. Generally speaking, vertebrate animals have two pairs of limbs.
There are five main classes of vertebrates: mammals, birds, fish, amphibians, and reptiles.
Dogs are vertebrate mammals.
Invertebrates are animals lacking a backbone: insects, spiders, shrimps and other crustaceans, molluscs, worms, and so many others.