Warning flags are up at Panama City Beach due to the presence of jellyfish, as well as Portuguese Man  o’ War, on the shore.

Social media photos show jellyfish, as well as a similar create the Velella, or “By-the-Wind-Sailor” clumped on the shore over the weekend. As of this morning, single red flags, indicting the presence of heavy surf and strong currents, as well as purple flags, an indication of dangerous marine life,” were flying.

Portuguese Man o’ War after often called jellyfish but are actually a species of  siphonophore, a group of animals that are closely related to jellyfish.

According to the National Oceanic and Atmospheric Administration, the Portuguese Man o’ War – a species known as a siphonophore and named for its resemblance to an 18th-century Portuguese warship at full sail – often float in large groups. They have balloon-like floats on the top, which may be blue, violet or pink, with long strands of tentacles under the water.

The tentacles contain stinging nematocysts that can deliver venom capable of paralyzing and killing small fish and crustaceans. The stings are rarely deadly to people but can cause extreme pain and welts on exposed skin. Even Man o’ War on the shore can be dangerous – they are capable of stinging even weeks after being washed on land, NOAA said.

Velella are also made up of a colony of tiny individual animals. Their “sails” allow it to catch the wind and travel on the currents. It uses its stinging tentacles to prey on young fish and other small animals.