Box jellyfish (Chironex fleckeri), artwork. This species of jellyfish, also known as the sea wasp, belongs to the cubozoa order of invertebrates. It has a cube-shaped bell (main body) that grows up to 30 centimetres in diameter and four groups of tentacles on each corner. The tentacles are lined with stinging nematocysts that are used to kill fish and crustaceans. The nematocysts contain a venom that causes severe pain, nausea, vomiting and respiratory problems in humans. In many cases death can result. Swimmers and divers can prevent stings, which only release venom on direct contact with skin, by wearing suitable clothing. Box jellyfish inhabit tropical and subtropical waters.