Three characteristics that are unique to mammals include their  ability to feed their babies with milk made in their mammary  glands. Mammals also have hair on their bodies â¦and they have a  single bone that makes up their lower jaw.
buoyancy. n. 1. the ability to float in a liquid or to rise in a fluid. 2. (General Physics) the property of a fluid to exert an upward force (upthrust) on a body that is wholly or partly submerged in it. 3. the ability to recover quickly after setbacks; resilience.
The buoyancy control device defined in claim 1, where the said means to adjust the said movable part has a means to lock the said movable part in place by friction or mechanical engagement, after an adjustment is made and while underwater.