1. Male animals that bear young, I'm lookin' at you Mr. Seahorse

2. Man o' War because they are amazing creatures, although they look like a jelly fish they are infact a colonial creature (kinda like the Borg) made up of many many tiny creatures called zooids. These tiny creatures are all individuals and very highly specialized, they are so integrated that they cannot survive on their own and only live because they integrate together.
http://cdn2.arkive.org/media/AE/AE65...ea-surface.jpg
3. Animals who can change gender based on the population. and situational demand. Like the clown fish or the warasses.
http://animal-world.com/encyclo/mari...eWMW_Ap8SW.jpg
4. That the fish I keep, rear their young, form lasting pairs and trios, and hold territories, that they have homes and families in my tank and I get to watch their behavior.
5. Weedy sea dragons.