Pose of tranquility

Yoga postures, who gave them names? Some are seriously misleading and most are just weird.

Take for example:

Sunbathing Spider: lie on your back with arms and legs stretched up in the air and flex/stretch hands and feet. I can count 4 limbs, I thought spiders had 8?

Pose of Tranquility: Lie flat on your back, 'throw' your feet over your head (so you have your legs above your face and the feet behind it) and balance on your shoulders. Once you have found balance move your arms above your head and grip you ankles. Keep balancing til you suffocate. I guess that is one way to reach tranquility.