The stomach has three types of contractions: There are rhythmic, 3 per minute, synchronized contractions in the lower part of the stomach, which create waves of food particles and juice which splash against a closed sphincter muscle (the pyloric sphincter) to grind the food into small particles.
7 What is the gestation period, how many babies do they have, and when are they weaned? 1  The gestation period for rats is 19â22 days, for mice it is 17â21 days.  Rats and mice average 8â12 babies in a litter, but can have as few as 1 or as many as 20.
The house mouse, roof rat, and Norway rat can reproduce year-round when adequate food, water, and harborage are available. The average female house mouse can produce up to 8 litters peryear with and average litter size of 4 to 7 pups. Rats can reproduce upto 6 times a year with litters averaging from 4 to 8 pups each. Each night, rats can travel from 100 to 300 feet from the nest insearch of food. House mice can search for food and nesting materials inan area as small as 10 feet from the nest or as far as 50 feet away.