Sea urchins are a group of spiny sea animals that are related to sand dollars and starfish. They can easily be mistaken for shells or rocks because of their hard, round, spiny bodies.

Sea urchins are primitive animals, but they boast a powerful defense mechanism. Their stings can be extremely painful and may cause extensive damage to the skin, tissue, and even bone.

The calcium-filled spines that a sting can leave behind can be difficult to remove from the skin. Prompt extraction of them, however, can prevent further injury.

Fast facts on sea urchin stings:

  • Most sea urchin stings are a painful annoyance only.
  • The spines hurt when they enter the skin, as a large splinter would.
  • Anyone with a history of allergic reactions to stings or bites should get medical help after a sea urchin sting.
  • The only way to completely avoid a sea urchin sting is to stay out of the ocean.

Some sea urchin species are more dangerous than others.Share on Pinterest
Some sea urchin species are more dangerous than others.

Sea urchins are covered in calcium-filled spines that warn predators of danger. Predators who fail to heed the warning may end up with spines in their skin.

Most sea urchin stings are akin to stepping on a large splinter or other sharp objects. The injury can be painful and may cause an infection but rarely does lasting harm.

Can sea urchin stings be fatal?

Some sea urchins are more dangerous than others. A few species have venomous spines with potent and potentially deadly effects.

The flower urchin, for example, is covered in tiny venomous spines. Few people have reported stings by a flower urchin, and researchers do not know much about how the venom works or how frequently it kills. These urchins are common in the Indian and Pacific oceans.

Some sea urchins "bite," and a few have venomous bites. Unlike a sea urchin sting, a bite does not leave spines behind.

Sea urchins may also trigger allergic reactions that can range from mild to potentially deadly. People with a history of allergic reactions to bites or stings may be more vulnerable.

Vinegar may be used to treat sea urchin stings, as it will help to dissolve the stings trapped in the skin.Share on Pinterest
Vinegar may be used to treat sea urchin stings, as it will help to dissolve the stings trapped in the skin.

First aid for sea urchin stings requires prompt removal of the spiky spines.

Removing sea urchin spines with tweezers can cause them to break and splinter at the skin's surface.

The spines might appear to be gone but can remain in the deeper layers of skin. Instead, it is advisable for a person to soak the affected area in vinegar. Vinegar can help dissolve the spines.

The spines are gone when they are no longer protruding from the skin, and there are no black or gray dots remaining at the surface of the skin.

If the first vinegar soak does not remove the spines, a person should continue applying vinegar compresses several times a day until the spines are gone.

Warm compresses can help with pain and swelling. Nonsteroidal anti-inflammatory drugs, such as ibuprofen, can also relieve pain.

In the days following the injury, a person should keep the wound clean and apply a triple antibiotic ointment. If the wound is red or itchy, topical hydrocortisone cream may help.

When to seek medical care

An allergic reaction to a sea urchin sting can occasionally be life threatening.

People who have a known allergy to sea urchins or other echinoderms, including starfish, should immediately go to the emergency room if they are stung.

People should seek emergency care or call 911 for the following symptoms:

  • difficulty breathing
  • loss of consciousness, dizziness, or mood or behavior changes
  • a sudden rash on a different area of the body from the sting
  • extensive swelling near the sting

If someone is stung or suspects they have been stung by a venomous sea urchin, it is a medical emergency. They should go to the emergency room or call 911.

Some of the signs that the sea urchin sting may have been venomous include:

  • dizziness
  • changes in heart rate
  • loss of consciousness
  • nausea or vomiting
  • difficulty breathing

When a sea urchin spine breaks off under the skin, it can migrate elsewhere in the body. If this happens, it may require surgical removal. If it is possible to feel a spine under the skin, if a spine is visible underneath the skin, or the spine has broken off, a person should contact a doctor.

When a spine is trapped under the skin or even after a spine is successfully removed, it is possible to develop an infection from a sea urchin sting.

Signs of an infection include red streaks coming out of the wound, an increase in pain, heat at the site of the wound, intense swelling, or a fever. A doctor should be contacted to treat signs of infection from a sea urchin sting.

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Sea urchin stingers may become stuck in the skin, like a splinter.
Image credit: Simon Mer, (2017, July 7).

The sea is full of stinging, biting creatures. Some people develop skin irritations or allergic reactions to sand, sunscreen, or any number of other products used at the beach.

Sea urchin stings can easily be confused with jellyfish stings. Both occur suddenly and can be intensely painful. Jellyfish may also leave behind tentacles that can resemble sea urchin spines to someone unfamiliar with sea urchins.

The telltale symptoms of a sea urchin sting include:

  • Bloody red puncture wounds: While a jellyfish sting can irritate the skin, sea urchin stings puncture the skin.
  • Spines sticking out of the skin: The spines are hard and spiky, not soft, as are tentacles.
  • Sudden intense pain: It can resemble a bee sting or injection, and the pain may penetrate into the muscle or deeper layers of skin.

Wearing water or beach shoes can lower the risk since many people are stung by sea urchins lurking on the ocean floor. Avoiding areas that have a large number of sea urchins or where people are frequently stung can also help.

People with a history of anaphylactic reactions to sea urchin stings should consider staying out of the water. Talking to a doctor about a reaction is advisable since it could be to a specific type of sea urchin only.

Avoiding waters in which sea urchins live might be a way to continue swimming in the ocean while lowering the risk of a future sting.