The box jellyfish is the deadliest jellyfish in the world. While most types of jellyfish are harmless, a single box jellyfish contains enough venom to kill 60 people.
The sting of the box jellyfish causes a burning sensation and excruciating pain, and the jellyfish's venom causes damage to the heart, nervous system and skin. Each box jellyfish tentacle has approximately 5,000 stinging nematocysts that resemble tiny darts. These darts fire when the tentacle touches its prey.
A person stung by the box jellyfish will die within two to five minutes without medical assistance. Immediate medical assistance increases chances of survival considerably. In areas within the box jellyfish's range, ambulances are equipped with jellyfish antivenom.