Porpoise-full Blog!
This, like my “You Otter Know” blog, is aimed at clearing up species confusion and offering some support to my fellow marine educators.
Yes, I am writing this for much needed educational porpoises. Sorry! I will attempt to restrain myself from further bad puns (but I am counting on you, the readers, to come up with some doozies).
Oh the number of times I have had the joy of an exchange like this:
Me: “Look, a porpoise!”
Response: “Ja, ja, een delfin!” or “Oui, oui, un dauphin” or “Ja, ja, een dolfijn” or “Yes, yes, a dolphin!”.
Me (armed with images like those below): “Nein – een schweinswal” / “Non – un marsouin” / “Nee – een bruinvis” / “Nope – it really is a porpoise!”
It is so understandable that there is significant confusion. The words dolphin and porpoise were, colloquially, used as if they were synonyms into at least the 1970s.
But, dolphins and porpoises are more distinct than lions and tigers. Lions and tigers are not only in the same family but in the same genus. Dolphins and porpoises are in different families, having diverged around 15 million years ago.

That’s no dolphin! It’s a Dall’s Porpoise. ©2015 Jackie Hildering.
The differences between porpoises and dolphins span from fin and head shape, to behaviour, vocals and average group size.