Stepping on a sea urchin causes a painful puncture wound from its sharp, brittle spines, which are primarily composed of calcium carbonate. These spines often break off within the skin upon impact. While most injuries cause intense localized pain, some species also possess tiny claw-like structures called pedicellariae that can inject a mild venom. Prompt first aid is necessary to manage discomfort and prevent complications like infection. The primary concern is safely removing the foreign material lodged beneath the skin.
Immediate First Aid and Pain Relief
After a sea urchin puncture, exit the water and inspect the injury site. Quickly rinse the area with clean water to wash away loose debris or any clinging pedicellariae. Do not scrub the wound vigorously, as this can press spines deeper or cause them to shatter.
Pain relief and venom neutralization are addressed through heat immersion. Submerge the affected area in hot water, between \(110\) and \(113^{\circ}\text{F}\) (\(43\) to \(45^{\circ}\text{C}\)), ensuring the temperature is tolerable without scalding. Soaking the injury for \(30\) to \(90\) minutes helps denature heat-sensitive venom. The warmth also reduces pain and softens the skin, preparing the area for spine removal.
Safe Techniques for Removing Spines
After the initial hot water treatment, carefully assess the embedded spines to determine the removal strategy. Larger, accessible spines protruding from the skin can be gently pulled out using sterilized tweezers. The goal is to grasp the spine close to the skin and remove it with a steady, straight motion to avoid breaking the brittle structure. It is important to avoid squeezing or probing the wound with unsterilized tools, as this can push the spine deeper or introduce bacteria.
For the numerous, smaller spines that have splintered or are embedded just beneath the surface, a chemical approach is often recommended. Since these spines are made of calcium carbonate, they can be dissolved by a mild acid. Soaking the affected area in white vinegar, which contains acetic acid, can help break down the calcareous material.
The vinegar application should involve soaking the area or applying a compress soaked in vinegar for several hours or even repeatedly over a few days. The spines are considered removed when the dark spots they cause in the skin are no longer visible and the pain subsides. If the spines are deeply lodged, attempting to dig them out manually is ill-advised, as this significantly increases the risk of infection and tissue damage.
Recognizing and Addressing Complications
After initial first aid, observe the wound for signs of infection. Symptoms such as increased redness, swelling, warmth, or pus may indicate a bacterial infection. If pain persists or increases beyond four to seven days, a retained spine fragment or unresolved infection may be the cause.
Seek immediate emergency medical attention if systemic reactions occur, indicating a severe venom or allergic response. These signs include difficulty breathing, muscle weakness, fainting, widespread rash, or paralysis. Deep puncture wounds, especially those near a joint, tendon, or nerve, also warrant professional medical evaluation. Spines remaining near a joint may require surgical removal to prevent long-term complications like inflammation or joint stiffness.