Answer:
The given muscles can be categorized into following categories:
Smooth muscles: These are involuntary muscles and non-striated muscles which are usually found within the walls of internal organs such as stomach, intestine, uterus et cetera.
Cardiac muscles: These are involuntary and striated muscles which are only associated with the heart.
Skeletal muscles: These are voluntary in nature and striated in structure. They are anchored to the bones with the help of tendons. They help in skeletal movement such as maintaining posture, locomotion et cetera. For example, hand muscles and neck muscles.
They may have ran out of oxygen, or they may not have been water dwelling snails, as not all are, lack of food, no flow of water into and out of the tank would cause them to run out of oxygen.