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.
Best Answer: As with most mammals the number will vary, but generally opossums will give birth to between 6-25 young one to three times a year, usually between January and July. Most litters consist of 6 to 9 young. Of these no more than 13 will survive because the mother only has 13 teats with which to feed them.