(WGHP) — If you have plans to go to the beach over the summer, keep an eye out for a potentially dangerous sea creature.

Biologists have seen a rise in Portuguese man o’ war sightings in Virginia.

They are related to jellyfish, but they move and look different.

Portuguese man o’ war stings can be extremely painful and deadly for anyone who has an allergic reaction to the venom.

They have tentacles that are usually 30 feet or longer with thousands of sharp barbs.

Experts with the National Oceanic and Atmospheric Administration say the venom can be active for weeks after a Portuguese man o’ war washes up on shore.

Beachgoers are asked to be mindful while out and about.