Pufferfish

Pufferfish are a group of fish species found in tropical and subtropical oceans worldwide, with a few species also living in brackish and fresh water, best known for their remarkable defense mechanism of rapidly inflating their elastic, spineless or spiny stomach with water or air when threatened, transforming into a much larger, harder-to-swallow ball shape that deters most predators. Many pufferfish species also carry a potent neurotoxin called tetrodotoxin concentrated in their skin and internal organs, among the most toxic substances known in nature, making improperly prepared pufferfish, served as a delicacy called fugu in parts of East Asia, potentially lethal to eat. Pufferfish are generally slow, somewhat clumsy swimmers that rely on their toxicity and inflation defense rather than speed to survive, and some species are also notable for elaborate courtship behaviors, including intricate circular patterns some males construct on the seafloor to attract a mate.