Rigor mortis occurs in a dead animal because?

The muscles in a dead animal start to stiffen and become rigid due to a process known as rigor mortis. This happens because the body's supply of adenosine triphosphate (ATP), which is a molecule that provides energy for muscle contractions, is depleted after death. Without ATP, the muscles can no longer relax, and they become fixed in the position they were in at the time of death.

The onset and duration of rigor mortis vary depending on factors such as the animal's species, age, and environmental conditions. In general, rigor mortis begins within a few hours of death and reaches its peak within 12 to 24 hours. It then gradually subsides over a period of several days.

Rigor mortis is an important part of the decomposition process, as it helps to break down the muscle tissue and release nutrients that can be used by other organisms.