Find out why we classify whales as mammals, not fish. Life processes - Variation and classification - Vertebrates Learning Points Mammals are one of the five types of vertebrates. Mammals give birth to live offspring, suckle their young with mammary glands, have hair or fur and are warm-blooded. A Twig Curriculum Film. Delivering key learning points. Get straight to the facts in just three minutes – directly linked to core learning, Twig's curriculum films will fit neatly into your lesson plans.