What happens to hair muscles when body temperature drops?

When body temperature drops, the hair muscles, also known as arrector pili muscles, contract. This contraction causes the hair follicles to pull the hair upright, resulting in the hair standing on end. This physiological response is part of the body’s mechanisms to conserve heat. By raising the hair, a layer of insulation is created, which helps to trap air and retain body warmth. Additionally, this reaction can make the animal appear larger and more intimidating to potential threats. This response is more pronounced in animals with fur as opposed to those with little or no body hair.