7. Portuguese Man-of-War
The Portuguese Man-of-War isn’t the nicest thing you can encounter in the beach. Its tentacles contain venomous nematocysts to paralyze small fish and other preys. Its stings can be very painful to human, leaving red, whip-like welts that last a couple of days. In rare cases, Portuguese Man-of-War can cause extreme allergic reactions and death. It is not recommended to use vinegar or urine to treat the welts, while saltwater may help. Apparently, clownfish seems to be immune to the Portuguese Man-of-War, perhaps owing to its mucus layer.