Australia’s marine and estuarine environment is home to many interesting animals, including some harmful jellyfish collectively known as marine stingers. These marine stingers are easy to avoid but can cause discomfort if you are stung, and some of the tropical species, such as the Irukandji and Chironex fleckeri (the Box Jellyfish) can be lethal. So, to ensure you enjoy your day at the beach, always remember to swim at a patrolled beach and look out for the safety signs.

Marine stingers are classified under the Phylum Cnidaria, being a group of animals that occur in polyp and/or medusa phases, are radially symmetrical, usually with tentacles and contain stinging cells produced by the animal itself. Examples of Cnidarians include a range of animals from corals and sea anemones to hydroids and marine stingers. The three classes of marine stingers that can inflict a painful sting include the Class Hydroza, Class Scyphozoa and Class Cubozoa. The term 'box' jellyfish can often confuse people as it is a general term used to describe Cubozoan jellyfish, including Irukandji, the Jimble and Chironex fleckeri (commonly known as 'box jellyfish'). Whilst these are the individuals pose the greatest threat, within the other two classes are the blue bottle and hair jelly which can cause much discomfort. The intensity and severity of the sting from a marine stinger varies with geographical location and a the health and fitness of the victim.

Below is a list of marine stingers that inhabit both the inshore and offshore waters surrounding Australia.

 

Carybdea
Transparent bell with 1.5-3 centimetres in diameter. Four tentacles, one in each corner, 5-15 centimetres long.

Catostylus
Mushroom shaped bell 5-30 centimetres in diameter. No tentacles, but eight 'fronds' or 'frills' hanging underneath.

 

Chironex
A large but almost transparent jellyfish with a box shaped bell (with 4 corners) up to 30 centimetres in diameter. Up to 15 ribbon-like tentacles arise from each of the four corners (up to 60 tentacles in total).

Cyanea
Large flat bell up to half a meter in diameter with a large 'mop' of fine hair-like tentacles 5-50 centimetres long.

 

Irukandji
Small transparent box jellyfi sh, 1-2 centimetres in diameter, usually not seen. Some newly described species may be larger (up to 10 centimetres).

Morbakka
Large transparent box-shaped bell with one tentacle in each corner. The bell is approximately 6-18 cms having 4 thick, ribbon-shaped tentacles that may be up to 1 metre long.

 

Pelagia
A small mushroom-shaped body from 2-6 centimetres in diameter. Unlike most jellyfish, the bell is covered with numerous warty lumps containing nematocysts (stinging cells).

Physalia
Air-fi lled sac up to 8 centimetres in length, usually with a single, long, blue main fishing tentacle hanging underneath.