Most jellyfish stings are harmless and occur by accident when people come in contact with the tentacles. Some varieties of jellyfish are more poisonous than others, such as the box jellyfish from Australia. Most stingray injuries require emergency care. To prevent injury, avoid swimming in areas where there are sightings of jellyfish or stingrays.

Jellyfish tentacles release thousands of very tiny stinging cells (nematocysts) that attach to the surface of the skin releasing venom, whereas, the stingray uses its hard barbed tail that is serrated with small venom-containing spines that penetrate the skin.

The tentacles of a jellyfish release a poison that results in a skin eruption, in the form of a painful red rash that itches. The sting usually causes a sting mark, pain and swelling, which may last several days to several weeks. Both jellyfish and stingray stings also can cause life-threatening shock and allergic reactions.

The sting of a stingray causes a bleeding wound that may become swollen and turn blue or red. It causes excruciating pain and can result in death. Severe symptoms may include nausea, fever, muscle cramps, paralysis, elevated heart rate and seizures.

If stung by a jellyfish or stingray:

• Carefully remove any tentacles or stingers still on the body. Make sure to cover your hand or use a tool — do not directly touch the tentacles or you will be injured.
• Soak jellyfish stings in salt water or vinegar (fresh water will increase pain and may release more of the toxin).
• Soak stingray stings in hot (but not scalding) water until the pain diminishes.
• Wash and bandage.
• For stingray stings, apply pressure to stop the bleeding. If necessary, and you are trained to do so, perform CPR.
• If an allergic or life-threatening reaction is observed, call 911 or your local emergency number immediately.