5 Dangerous Animals You’ll Want to Avoid

2. Box jellyfish
Stay away from these little buggers. Often found floating in the waters north of Australia, these transparent, nearly invisible invertebrates are considered by NOAA to be the most venomous marine animal in the world. Their namesake cubic frames contain up to 15 tentacles at the corners, lined with barbs. Known as nematocysts, they contain toxins that simultaneously attack the heart, nervous system, and skin cells.