act as the functional units of the respiratory system by passing oxygen into the body and carbon dioxide out of the body. Finally, the muscles of respiration, including the diaphragm and intercostal muscles, work together to act as a pump, pushing air into and out of the lungs during breathing.
The Ivory-billed Woodpecker (Campephilus principalis) is an extremely rare member of the woodpecker family, Picidae. It is officially listed as an endangered species, but by the end of the 20th century had widely been considered extinct until it was apparently sighted along the Cache River in Arkansas in 2004 and 2005.
Elephant ivory is the most important source, but ivory from mammoth, walrus, hippopotamus, sperm whale, killer whale, narwhal and wart hog are used as well. Elk also have two ivory teeth, which are believed to be the remnants of tusks from their ancestors.n Asia, wild elephant populations are now a fraction of what they were in historic times, and poaching of elephants continues. Elephants are now close to extinction in China, Vietnam, Laos PDR, Cambodia and Indonesia. Instances of theft of even domestic elephants for their ivory have been recorded in Myanmar.