Trachea act as a resonator to amplify sound. In some birds, the tracheal rings are complete, and may even be ossified. In amphibians, the trachea is normally extremely short, and leads directly into the lungs, without clear primary bronchi. A longer trachea is, however, found in some long-necked salamanders, and in caecilians. While there are irregular cartilagenous nodules on the amphibian trachea, these do not form the rings found in amniotes. The only vertebrates to have lungs, but no trachea, are the lungfish and the "Polypterus", in which the lungs arise directly from the pharynx. The word "trachea" is used to
Explorers of the Human Body weeks. It was later decided that instead of a hiatus, the program will end the season with thirteen episodes. Super Junior decided to leave the show due to their occupied schedules and busy preparations for their upcoming Asia-wide concert tour, Super Show. However, representatives of the program stated if there is a chance, a second season is considered. "Change", the variety program hosted by Lee Hyo-ri and Shin Dong-yup with Noh Hong-chul, Kangin, Son Ho-young and Min Kyung-hoon as regulars, took over the time slot. Explorers of the Human Body Explorers of the Human Body (Hangul: 인체탐험대; Hanja: 人體探險隊) was