Genus Physalia is commonly known as the Portuguese man o' war, a predatory marine invertebrate with venomous tentacles that can cause painful stings to humans. For those who find the name Genus Physalia difficult to say or remember, there are several synonyms that can be used instead. These include Bluebottle, Stinger, or Floating Terror. While these names might sound less scientific, they nevertheless convey the danger associated with encountering these creatures. Some related species are also referred to as man o' wars, such as the Pacific man o' war or the Atlantic man o' war. Regardless of what you call it, this sharp creature is certainly one to avoid when you're near the shore!