The Irukandji Jellyfish is a very small jellyfish which makes it really hard too see in the water. They live in northern areas such as the Great Barrier Reef Queensland Australia. These animals may be very small but there very venomous, when they sting you the venom only takes half an hour for an adult to be in hospital and the damage done by the creature is unnoticed
This picture is showing how small these creatures are.