What animal sneaked into Australia on the hull of a ship?

The animal that sneaked into Australia on the hull of a ship is the cane toad (Rhinella marina). Originally introduced in the 1930s to control pests in sugarcane fields, the cane toad has since become an invasive species, causing harm to native wildlife due to its toxic skin secretions. The introduction of cane toads is a classic example of unintended consequences in ecological management.