The number 7

Well, that is 7 years of blipping under my belt; how the years do fly by. I have very much enjoyed the journey in this friendly and supportive community.

Searching for something on the theme of 7 I have chosen this skeletal structure.

All mammals except manatees and sloths, but including the giraffe, have 7 cervical (neck) vertebrae, whatever the length of the neck. Sloths possess 5-9 whilst manatees have but 6. 

In the whales the 7 cervical vertebrae are typically much reduced in size and fused together, an adaptation that provides great stability during fast swimming at the expense of them not being able to easily turn their heads. These are the fused vertebrae of a porpoise washed up on Newburgh beach, as seen from the back.