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Why can cane toads be dangerous to freshwater crocodiles?

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Illustration of an estuarine or saltwater crocodile (Crocodylus porosus) with its mouth open, showing scaly skin and powerful limbs, alongside a scale bar for size reference. — crocodile Estuarine, or saltwater, crocodile (*Crocodylus porosus*), found in brackish waters from Sri Lanka, India, Bangladesh, and Myanmar east to the Solomon Islands and Vanuatu and south to Australia.

Cane toads (Rhinella marina) are dangerous to freshwater crocodiles (Crocodylus johnsoni) because they are highly toxic. These invasive amphibians possess large parotid glands that secrete a milky white toxin known as bufotoxin.12

This toxin contains cardioactive steroids that directly affect the heart and central nervous system of predators. When freshwater crocodiles consume cane toads—often mistaking them for local prey—they can suffer fatal poisoning. This interaction has notably impacted the population structure of freshwater crocodiles in Australia, leading to a reduction in the number of intermediate-sized individuals.132