Catostylus mosaicus Click to enlarge image
Jelly Blubber, Catostylus mosaicus Image: Dr Isobel Bennett
© Australian Museum

Fast Facts

  • Classification
  • Size Range
    30 cm


Jelly Blubbers are one of the most commonly encountered jellyfish along the east coast of Australia. They often aggregate in large numbers particularly in harbours or estuaries but they also occur in open water. Additionally, these jellyfish have been trialled for commercial fisheries.

What do Jelly Blubbers look like?


Jelly Blubbers have a hemispherical or mushroom shaped bell that can reach 30 cm in diameter. Their colour ranges from bright blue to creamy white, or even brownish-yellow. They have eight textured oral arms that hang underneath the bell.

Jelly Blubber, Catostylus mosaicus.
Jelly Blubber, Catostylus mosaicus. Image: Lucy Smiechura
CC BY-NC 4.0 (

Where do Jelly Blubbers live?


Jelly Blubbers are usually found in harbours or estuaries, though they can be found in open water. They typically occur between the middle and surface of the water column, and occur in shallow areas (< 30 m depth).


Jelly Blubbers are found in Queensland, New South Wales and Victoria.

What do Jelly Blubbers eat and what is their life cycle?

Feeding and diet

Jelly Blubbers capture larvae and small crustaceans using stinging cells (nematocysts), located in their oral arms. They then pass this food through to their multiple mouths, which are spread along their arms.


Jelly Blubbers typically occur from Summer to Autumn.

Life history cycle

The adult stage of a jellyfish is called the medusae phase, which release planula larvae that attach to hard substrates and become what is known as a polyp. The polyp stage looks similar to a small anemone, and when the conditions are right, the polyps will go through a process called strobilation. This is the budding of the medusae stage from a polyp, and 1-5 medusae can come from a single polyp.

Jelly Blubber, Catostylus mosaicus.
Jelly Blubber, Catostylus mosaicus. Image: Claire Rowe
© Australian Museum

What are Jelly Blubber behavioural adaptations?

Behaviours and adaptations

Jelly Blubbers are able to swim by pulsing their bell, which propels them forward in the water column. Additionally, these jellyfish are sometimes associated with fish or small crustaceans called copepods (Paramacrochiron maximum), which may consume the mucus of Jelly Blubbers.

Are Jelly Blubbers dangerous?

Danger to humans

The nematocysts can cause mild irritation to the skin. However, they are not considered to be a significant risk to humans.

How to treat a Jelly Blubber sting:

  • Do not apply freshwater or vinegar as they will cause more nematocysts to be released.
  • Do not rub the sting, as this will also cause more nematocysts to be released.
  • Apply hot water for 20 minutes, or if hot water is unavailable an ice pack to reduce swelling.
  • Seek medical attention if symptoms persist.