# Heinlein question -- "Gulf" & "Friday" (open spoilers)

**URL:** <https://boards.straightdope.com/t/heinlein-question-gulf-friday-open-spoilers/557715>\
**Category:** Cafe Society\
**Created:** [October 19, 2010, 11:30pm UTC](https://boards.straightdope.com/t/heinlein-question-gulf-friday-open-spoilers/557715 "2010-10-19T23:30:20Z")\
**Posts on this page:** 1\
**Showing post:** 51

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**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\
**Post date:** [March 19, 2015, 2:17pm UTC](https://boards.straightdope.com/t/heinlein-question-gulf-friday-open-spoilers/557715/51 "2015-03-19T14:17:40Z")

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> [@MIchelleRose](#):
>
> Definitions: dolphins are fish, _coryphaenidae_, like the pompano. Porpoises are the mammals we know as bottlenose dolphins. The two terms are often mixed, much to the grief of marine biologists. I know a couple and they always frown when I use the term “dolphin” to describe _tursiops truncatus_. Bad form, doncha know.

Actually, AIUI, there are [porpoises](https://creelmanresearchlibrary.wordpress.com/the-endless-allure-of-non-hierarchical-organizations/) and there are also mammalian [dolphins](http://en.wikipedia.org/wiki/Dolphin), two different groups of species.

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