Reproduction
The Blue Dragon doesn't usually need a partner to reproduce... They can do it all on their own. If they do mate with a partner, they go to lay eggs on floating pieces of wood or plastic. Then, the little eggs hatch and release hundreds of poisonous slugs into the ocean!
Never Touch Them!
There are some photos of people holding them, which indicates that they weren't being hurt... The venom won't always attack instantly. In fact, it's common for it to leave a horrific rash on the skin. The people who took photos holding them probably had a lengthy hospital bill.