# Colors **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [January 25, 2011, 6:19am UTC](https://boards.straightdope.com/t/colors/568889 "2011-01-25T06:19:42Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![needscoffee](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/needscoffee/32/1076_2.png) [@needscoffee](https://boards.straightdope.com/u/needscoffee)\ **Post date:** [January 25, 2011, 7:29am UTC](https://boards.straightdope.com/t/colors/568889/2 "2011-01-25T07:29:23Z")
> [@cmoose](#): > > In grade school in the '30s I was taught the seven colors of the rainbow through the mnemonic name Roy G. Biv. Start with these and add a couple for brown and gray (grey in Cecil’s column) and you get about nine as a basis on which to build - though indigo does not seem very basic. The other six do include the three primary and the combinations from mixing them in pairs. > [@Shark, You're what's for dinner: How quickly can sharks pick up on blood in the water](https://boards.straightdope.com/t/shark-youre-whats-for-dinner-how-quickly-can-sharks-pick-up-on-blood-in-the-water/460078/13): > > I appreciate Cecil’s noting that sharks have very keen hearing. In 1946 my father was stationed on Midway Island. He learned that when the garbage scow went out and began dumping that sharks appeared quickly. Flying around the island, he often spotted a group of sharks, sometimes a few miles from the scow, but noticed that when the began to dump garbage, the sharks would immediately turn and head for dinner! > It would seem that sharks would at least be aware of and alerted, if not attracted, to swimmers thrashing in the water. Are you your own father?? --- _[View the full topic](https://boards.straightdope.com/t/colors/568889)._