The term “sea rafts” is an informal name used by beachgoers to describe large groups of floating marine organisms occasionally washed ashore by strong winds and currents. This collective stranding, known as a “blue tide,” raises concern because some organisms involved have stinging capabilities. The primary question is whether these creatures are “poisonous,” which refers to their potential to deliver venom through specialized stinging cells. Understanding the danger requires distinguishing between the different types of floating organisms that form these aggregations.
Identifying the Common Floating Organisms
Two distinct colonial animals are most frequently responsible for sea rafts: the By-the-wind Sailor and the Portuguese Man O’ War. Both belong to the phylum Cnidaria, but they differ significantly in structure and danger level. The By-the-wind Sailor (Velella velella) is a small, oval-shaped hydrozoan typically measuring less than three inches long. It is distinguished by a clear, triangular, chitinous sail that projects diagonally above its deep blue float.
The Portuguese Man O’ War (Physalia physalis) is a siphonophore, a colony of specialized polyps working together. Its most noticeable feature is a gas-filled, blue or purple bladder that can reach up to twelve inches in length and floats prominently on the water’s surface. Unlike the small tentacles of the By-the-wind Sailor, the Man O’ War possesses extremely long, trailing tentacles that can extend many feet beneath the water.
Comparing Venom and Danger Levels
The danger depends entirely on which species is encountered, as both are venomous rather than poisonous; they actively inject toxins instead of having toxins that must be ingested. The Velella velella uses nematocysts, which are microscopic stinging cells, to paralyze its planktonic prey. However, the toxins in the By-the-wind Sailor’s nematocysts are considered benign to humans, causing little to no reaction in most people.
Contact with a Velella velella may cause only mild skin irritation. Beachgoers are advised to wash their hands after touching one before handling their eyes or mouth. In contrast, the Physalia physalis delivers a potent neurotoxin capable of causing intense, immediate pain. The pain from a Man O’ War sting can last for several hours and may result in whip-like red welts that can persist for weeks. While stings are rarely fatal, they can trigger systemic reactions, including muscle cramps, nausea, and in rare cases, severe allergic responses.
Immediate Safety and First Aid
Given the significant difference in danger, a cautious approach is best when encountering any washed-up marine organism. If contact occurs with a suspected Portuguese Man O’ War, the immediate goal is to prevent further venom injection and deactivate the toxins. Do not rub the affected area, as friction can cause remaining stinging cells to fire and release more venom.
The first step is to rinse the area thoroughly with salt water to flush away unattached tentacles; fresh water should not be used, as it can trigger unfired nematocysts. After rinsing, the most effective method for pain relief and toxin neutralization is the application of heat. Immersing the affected limb in hot water (104°F to 113°F or 40°C to 45°C) for 20 to 45 minutes can help deactivate the venom. Seek emergency medical attention if the stung person experiences difficulty breathing, chest tightness, or signs of a severe allergic reaction.