When walking along a beach, you might encounter peculiar blue, jelly-like organisms that have washed ashore. Often mistaken for jellyfish, these intriguing marine creatures are a common sight in coastal areas worldwide. Understanding what they are, why they appear on beaches, and how to interact with them safely can enhance your beach experience and knowledge of marine life.
Common Blue Marine Organisms
Among the most frequently encountered blue, jelly-like organisms on beaches are the Portuguese Man O’ War and the By-the-wind Sailor. While they may appear similar, these two species have distinct biological classifications and features.
The Portuguese Man O’ War (Physalia physalis) is not a single animal but a colony of specialized organisms (zooids or polyps) that function as one entity. These polyps are incapable of independent survival, relying on each other for feeding, reproduction, and locomotion. It has a prominent, gas-filled float, often blue, violet, or pink, that rises above the waterline. Long tentacles, extending up to 30 feet, trail beneath this float, armed with stinging cells for capturing prey and defense.
Another common sight is the By-the-wind Sailor (Velella velella). This hydrozoan, related to jellyfish, is a colonial organism with a flat, oval, deep blue disc. A distinguishing feature is a clear, triangular sail that projects vertically, allowing it to catch the wind and drift across the ocean surface. It has tentacles with stinging cells, though these are generally harmless to humans.
A less common but similar-looking organism is the Blue Button (Porpita porpita). This colonial hydrozoan appears as a flat, circular disc with polyps resembling tentacles around its edge. It floats on the surface of warm, tropical, and subtropical waters. While it possesses stinging cells, its sting is mild and not dangerous to humans.
Why They Appear on Beaches
These blue marine organisms are pelagic, living in the open ocean and lacking the ability to swim against strong currents or winds. They rely entirely on ocean currents and winds for movement, making their appearance on beaches a natural consequence of their passive lifestyle and interaction with environmental forces.
Persistent onshore winds are a primary factor driving these creatures from the open sea to the shore. When winds consistently blow towards the land, vast numbers of these passively floating organisms can be carried along and stranded. Ocean currents also play a significant role in their distribution, transporting them over long distances before they encounter coastal areas.
Tides further contribute to their stranding. As high tides bring marine life closer to the shore, a receding tide can leave these organisms behind on the sand. Once caught in these forces, they become beached, often in large numbers.
Staying Safe Around Them
Encountering these blue, jelly-like organisms on the beach requires caution, as some, particularly the Portuguese Man O’ War, can deliver a painful sting. Avoid touching any such objects, even if they appear dead or dried out, because their stinging cells can remain active for hours or even days after washing ashore. A Portuguese Man O’ War sting can cause intense burning pain, red welts, and may lead to more generalized symptoms.
If you or someone else is stung, the immediate action should be to rinse the affected area with saltwater, not fresh water, as fresh water can cause more stinging cells to discharge. Carefully remove any visible tentacles using tweezers or a gloved hand, avoiding bare skin contact. Applying heat to the sting site, such as immersing it in hot water (around 104-113°F or 40-45°C) for 20-45 minutes, can help to inactivate the venom and alleviate pain.
Avoid applying vinegar to Portuguese Man O’ War stings, as this can sometimes worsen the reaction by causing more venom release, unlike its effect on some true jellyfish stings. Seek medical attention for severe reactions, extensive stings, or if the sting occurs on sensitive areas like the eyes or mouth, or if pain persists or symptoms worsen.