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Stinging jellyfish

Classifying box jellyfish

Chirodropid jellyfish

Carybdeid jellyfish

Distribution & abundance

Life cycle

Vision & movement

Feeding & venom

The sting

Irukandji syndrome

Preventing the sting

Future research

First aid

Other stinging jellyfish

More information

Bluebottles and Pacific man-o-war

Physalia species cause stings that are similar to those from jellyfish although these animals are siphonophores (hydrozoans) and not jellyfish (scyphozoans and cubozoans). About 10-30,000 stings each year are reported along the east coast of Australia from Physalia with about 500 reported from Western Australia and South Australia. No fatalities have been confirmed from these animals in the Southern Hemisphere but there have been several fatalities from related species in the Northern Hemisphere.

The bluebottle Photo by Lisa-ann Gershwin

Instead of the usual jellyfish bell, Physalia have a gas-filled sac that floats on the surface of the water and tentacles that hang underneath. Physalia can change the orientation of its float and use it to ‘sail’ with the wind. There are stinging cells (or nematocysts) in rows along the tentacles. The life cycle of these stingers is not known.

The bluebottle Physalia utriculus is Australia’s most common species. It has a blue float usually 20-80mm long (but can be up to 150mm long) which is wrinkled on the top. The bluebottle has a single main retractile tentacle hanging from the float that can be contracted to a few centimetres or extended to several metres long. Many shorter smaller tentacles may also hang from the float. The bluebottle is found in vast numbers on the eastern Australian coast every year. They also occur in South and Western Australia. The sting causes immediate pain which can last more than an hour. The pain is usually in the lymph glands draining the arms and legs.

It is possible that there are two other species of Physalia that are much larger than the bluebottle and have both been called Pacific man-o-war. The Pacific man-o-war is related to the Portuguese man-o-war from the Atlantic Ocean. The float of the Pacific man-o-war is 100-150mm long compared with the Portuguese man-o-war which has a float which can be 250-300mm long. The float of the Pacific man-o-war has 7-8 long retractile tentacles and many shorter, fine tentacles hanging from it. The long retractile tentacles can be extended to 10 metres long. The Pacific man-o-war causes a sting which is more painful than those from the bluebottle. The pain can be relieved by cold packs. In some cases, the victim may suffer a moderate Irukandji-like syndrome with back pain, and muscle cramps in the limbs, abdomen and chest.

CRC Reef Research Centre Ltd

PO Box 772 Townsville
Queensland 4810 Australia
Telephone: 61 7 4729 8400
Facsimile: 61 7 4729 8499
Email: info@crcreef.com
Website: www.reef.crc.org.au