The Pelagia jellyfish, scientifically known as Pelagia noctiluca, is a common marine organism found in various ocean environments. It is often called the mauve stinger or purple-striped jelly, names that refer to its appearance and stinging capabilities. This species is frequently seen in coastal and open ocean waters.
Distinctive Features and Habitat
The Pelagia jellyfish exhibits a mushroom-shaped bell, typically 3 to 12 centimeters in diameter, with an average size of about 6.5 centimeters. Its coloration varies, often appearing in shades of pink, purple, light brown, or yellow. The exumbrella, or upper surface of the bell, is covered with wart-like clusters of stinging cells called nematocysts.
Eight hair-like tentacles radiate from the bell’s margin, extending up to 3 meters in length. It also possesses four large, frilled oral arms used for feeding. This species is widely distributed in warm and temperate waters globally, including the Atlantic Ocean, Mediterranean Sea, and parts of the Pacific Ocean. While primarily an open ocean species, aggregations can drift into coastal areas, particularly during winter months.
Understanding Its Sting
The sting of the Pelagia jellyfish can cause immediate burning pain, often followed by local redness, swelling, and a rash. Contact may leave red, brown, or purplish tracks on the skin. Symptoms also include itching, tingling, and throbbing pain that can spread from the sting site. While generally not life-threatening, more severe reactions can occur, leading to symptoms like dizziness, nausea, vomiting, or blistering of the skin.
If stung, rinse the affected area with seawater, not fresh water, as fresh water can activate more stinging cells. Carefully remove any remaining tentacles using tweezers or the edge of a card, avoiding bare-hand contact. Soaking the stung area in very warm water (as hot as can be tolerated, ideally between 40 and 45 degrees Celsius) for at least 30 minutes can help alleviate pain by deactivating the venom. Over-the-counter pain relievers like paracetamol or ibuprofen can also be taken. Seek immediate medical attention if symptoms include difficulty breathing, chest pain, severe swelling, vomiting, or loss of consciousness.
Life Cycle and Ecological Significance
The Pelagia jellyfish possesses a unique holoplanktonic life cycle, completing its entire life cycle in the open water without a sessile polyp stage. Adults reproduce sexually by releasing gametes (ova and sperm) directly into the water through the jellyfish’s mouth. The resulting larvae develop directly into juvenile medusae, bypassing the bottom-dwelling stage seen in many other jellyfish species.
As a generalist predator, Pelagia noctiluca consumes various zooplankton, including copepods, appendicularians, chaetognaths, and the eggs and larvae of small fish. This positions it as a competitor within the marine food web. Large aggregations, known as “jellyfish blooms,” can occur, impacting marine environments and human activities. These blooms can interfere with fisheries by clogging nets, compete with fish for food, and prey on fish larvae, potentially affecting fish stocks. When large blooms die, their decomposition can consume oxygen, potentially leading to hypoxic “dead zones” in coastal areas.