Much maligned by swimmers in Australia (especially on the east coast), the Blue Bottle (also called Portugese Man of War) has a very painful sting.

Blue Bottle - Physalia utriculus also known as Portugese Man of War - Photo by Alex Pawlow

Although it is often thought of as a jelly fish, Blue Bottles are actually made up of colonies of different animals (known as a siphonophore) that all have specialised roles to play. They are so specialised that they can't survive independently.

The individual animals are polyps, and the float is one distinct animal that supports the other polyps which individually reproduce, digest food and capture prey.

They are in the same genus of the larger Physalia physalis, however they are also often found in large numbers.

The Blue Bottle has a single tentacle which it uses to sting and capture prey. The sting is from toxic nematocysts that can remain active for weeks after the Blue Bottle has washed up on the beach. If you see one, take a look but don't touch.

Their diet mainly consists of very small fish and crustaceans.

Although not usually serious, the stings are painful. If you are stung by one, do not use vinegar. Remove tentacles with tweezers or a glove and soak the area in hot water for 20 minutes and then use ice packs to relieve the pain.