Cannonball jellyfish, scientifically known as Stomolophus meleagris, are a common marine species often encountered in coastal waters across the Atlantic, Gulf of Mexico, and Pacific regions. These unique creatures are easily recognized by their distinct spherical shape and the absence of long, trailing tentacles typically associated with other jellyfish species. While their appearance might suggest a threat, cannonball jellyfish are generally considered to be mild in their potential impact on humans.
Recognizing Cannonball Jellyfish
Cannonball jellyfish possess a rounded, ball-shaped bell that is translucent and feels rigid, resembling a gelatinous sphere. Their bell can measure up to 25 centimeters (10 inches) in diameter, commonly ranging from 7 to 10 inches wide and about 5 inches tall. The color of their bell is typically whitish or milky, often featuring a distinct brown or reddish-brown pigment around its rim. Instead of long tentacles, a rigid stalk extends from beneath the bell, supporting a cluster of finger-like oral arms that surround a central mouth. These oral arms play a role in both propulsion and capturing their primary food source, zooplankton.
Cannonball jellyfish are particularly abundant along the southeastern coast of the United States, including the Gulf Coast, and are found from New England down to Brazil in the Atlantic, as well as from California to Ecuador in the Pacific. They frequently inhabit gulf and bay waters, often floating near the surface. These jellyfish are known to form large aggregations or swarms, which sometimes leads to many of them washing ashore.
Understanding Their Sting
The sting of a cannonball jellyfish is generally mild and causes very little impact on humans. Unlike some other jellyfish, their sting is not considered life-threatening and typically results in minor discomfort. When contact occurs, individuals often report a slight irritation, a mild burning sensation, or itchiness on the skin. This reaction is due to microscopic stinging cells called nematocysts, which are located inside their bell or on their oral arms.
Upon disturbance, cannonball jellyfish secrete a mucus from these nematocysts that contains a toxin. This toxin is primarily a defense mechanism against predators and a means to stun small prey. While effective against small fish, its effect on humans is usually limited to localized skin irritation. Direct contact with nematocysts, particularly if they get into sensitive areas like the eyes, can lead to more intense pain, redness, and swelling.
What to Do After a Sting
Should you experience a sting from a cannonball jellyfish, the immediate step is to exit the water. It is important to rinse the affected area thoroughly with seawater, not freshwater, as freshwater can cause more nematocysts to discharge and intensify the sting. If any visible tentacles remain on the skin, carefully remove them using tweezers; avoid rubbing or scraping the area, which can release more venom.
After rinsing and removing any remnants, immerse the affected skin in hot water, ideally between 43 to 45 degrees Celsius (110 to 113 degrees Fahrenheit), for 20 to 45 minutes. The water should be hot but not scalding. A hot shower can serve the same purpose and helps to alleviate pain.
Following the heat treatment, applying a 0.5% to 1% hydrocortisone cream twice daily can help soothe the irritation. Over-the-counter pain relievers, such as ibuprofen or acetaminophen, may also be used for discomfort. Avoid applying urine, alcohol, meat tenderizer, or baking soda, as these are ineffective and can worsen the sting.
Seek medical attention if you experience signs of a severe allergic reaction, such as difficulty breathing, chest pain, widespread rash, dizziness, or vomiting. Medical consultation is also advisable if the sting is located on the eyes, mouth, or throat, or if the pain is severe and persistent.
Staying Safe Near Jellyfish
Minimizing interactions with jellyfish, including cannonball jellyfish, involves a few practical measures. Staying informed about local jellyfish warnings, often indicated by specific lifeguard flags, can help you avoid areas where they are prevalent. Wearing protective clothing like wetsuits or rash guards, particularly during times when jellyfish are known to be abundant, offers a physical barrier against potential stings.
It is prudent to avoid touching or handling any jellyfish, even if they appear to be washed up on the beach and seem lifeless. The stinging cells on dead jellyfish can still discharge venom and cause a reaction.