In addition to providing insulation, blubber can also nourish mammals that go for long periods without feeding. Whales that migrate are just one example of a mammal that would rely on stores of blubber for fuel during a long journey. Polar bears, who may feed sporadically and in great amounts will also rely on their fat stores to sustain them through periods with little food. The cat family is one group of mammals that can retract their claws, or pull them inside the foot. Most mammals have claws that are not retractable, like a dog.
Claws are useful to mammals in a number of ways.
They can be used for both defense as well as in capturing prey. Sharp claws can help a predator hold on to its prey as well as deter other animals from taking its meal. Mammals also rely on claws to help with climbing and burrowing. Claws can help an animal scurry up a tree away from a predator. They can also help a mammal to dig deep below the earth in order to create a burrow for young, or an elaborate tunnel system for an entire family group, as in prairie dogs.