Australian Seals aren't actually seals at all, they're sealions. The naming guy got it wrong as he does so often underwater. However, sealions isn't a great name either. The fact is they would be better off being called seadogs.
Bottlenose dolphins are a lot like humans. Some are happy to find a home and rarely ever leave it, while others prefer adventure and head off to travel the world. In fact Bottlenose Dolphins are found in more places than any other marine mammal.
Dugongs are related to elephants, they weigh up to 400kg and have hairy backs, so just how anyone could mistake one for a mermaid is beyond me. You would have had to have been out at sea for a very, very long time indeed.
Okay, Fairy Penguins shouldn't really be in the 'Big Stuff' category, they are the smallest penguins in the world, but we like them too much to just put them in the 'Other Stuff' category. Everyone loves Fairy Penguins, but unfortunately that includes sharks and rays and even pet dogs, which is why they like to spend most of their life in their undergound burrows on land.
Green Turtles aren't called Green Turtles because of their green shells (sometimes the shells can be almost brown). Instead they get their name from their green fat which alledgedly is very green indeed - although we must admit we have never tried to discover this for ourselves.