The term for blue skin caused by lack of oxygen is cyanosis. One is said to be cyanotic when presenting with this discoloration.
Answer;
-Sympathetic nervous system
After cheering wildly at an exciting football game your body may begin to relax on the way home. This relaxation reflects activity of the sympathetic nervous system.
Explanation;
The sympathetic nervous system is part of the autonomic nervous system, which also includes the parasympathetic nervous system.
The sympathetic nervous system activates what is often termed the fight or flight response. Like other parts of the nervous system, the sympathetic nervous system operates through a series of interconnected neurons. Sympathetic neurons are frequently considered part of the peripheral nervous system (PNS), although there are many that lie within the central nervous system
The answer is Chordates
Most of the chordates have a symmetrical bilateral body which differentiated into head, trunk and tail
The example of chordates are parrot, penguin, horse , squirell, clown fish ( the one in finding nemo), sharks, etc
