Photograph by Rich Reid. Tundras are among Earth's coldest, harshest biomes. Tundra ecosystems are treeless regions found in the Arctic and on the tops of mountains, where the climate is cold and windy and rainfall is scant. Tundra lands are snow-covered for much of the year, until summer brings a burst of wildflowers.
Muscle is a soft tissue found in most animals. Muscle cells contain protein filaments of actin and myosin that slide past one another, producing a contraction that changes both the length and the shape of the cell. The statement that the tongue is the strongest muscle in the body appears frequently in lists of surprising facts, but it is difficult to find any definition of strength that would make this statement true. 2  Note that the tongue consists of eight muscles, not one.
What Muscles Do. 1. Contract (squeeze) and thereby cause the movement of different parts of the body. For example, they move joints and bones so we can do things like raise our arm and walk. Muscles move food along our digestive system, open and close our eyes, circulate blood through our body. Different types of muscles carry out different actions. 2. Keep joints (like the hip joint) stable and in place.