C. barnesi, commonly known as the Irukandji jellyfish, is a small, extremely venomous jellyfish found in Australian waters. It has a bell-shaped body about 2.5 cm wide and is nearly transparent. Known for its potent sting, it can cause Irukandji syndrome, leading to severe pain and potentially life-threatening symptoms.

Carukia barnesi, commonly known as the Irukandji jellyfish, is native to the northern waters of Australia, particularly in the regions off the coasts of Queensland and the Northern Territory. This species is primarily found in the Coral Sea and the Great Barrier Reef area.

The Irukandji jellyfish inhabits warm, tropical marine environments. These waters are typically clear and warm, with temperatures ranging from 24°C to 30°C (75°F to 86°F). The species is usually found in offshore waters but can occasionally be encountered in coastal areas, especially during the jellyfish season from October to May.

Carukia barnesi occupies a pelagic niche, meaning it lives in the open sea rather than near the bottom or the coast. It is a small, highly venomous jellyfish that primarily preys on small fish and other marine invertebrates. Its transparency and small size make it a stealthy predator, and it plays a role in controlling the population of its prey in the marine ecosystem.