Sea stars, invertebrates belonging to the phylum Echinodermata, are easily recognizable by their radial symmetry and arms radiating from a central disk. They are a common sight in shallow coastal areas, such as tide pools and coral reefs. Their accessibility often invites curiosity from beachgoers, leading to questions about whether these creatures can be safely handled.
Understanding the Biological Harm of Air Exposure
Removing a sea star from the water, even briefly, causes immediate and significant stress. Sea stars lack lungs or gills; instead, they rely on specialized structures called papulae (skin gills) and tube feet for respiration. These structures absorb dissolved oxygen directly from the surrounding seawater. Exposure to air prevents this gas exchange, leading to a form of suffocation.
Air exposure also disrupts the sea star’s specialized internal plumbing, known as the water vascular system. This hydraulic network is used for movement, feeding, and waste transport. The system operates entirely on water pressure, powering the hundreds of tiny tube feet on the underside of the animal. If air enters the system, it can introduce bubbles that function similarly to an embolism, potentially damaging the delicate internal structures. Mishandling causes a severe stress response that can result in chronic damage, illness, or death.
Safe Interaction Guidelines
The safest way to interact with sea stars is through observation without physical contact. If interaction is unavoidable, such as for a quick photograph or moving a stranded animal, the sea star must remain fully submerged in water at all times. If the animal is on a submerged surface, gently cup your wet hand underneath it to support its weight, ensuring its body never breaks the water’s surface.
Avoid touching the sea star with bare hands containing contaminants like sunscreen, insect repellent, or natural skin oils, as these substances can harm the animal’s sensitive outer layer. Never attempt to pry a sea star off a rock or coral, as this can tear its tube feet, which are necessary for movement. Always check local regulations before touching marine life, as many protected areas prohibit all physical interaction.
Starfish and Human Safety Concerns
While many common sea stars found in North American tide pools are generally harmless to humans, certain species pose significant health risks. The most widely known danger is the Crown-of-Thorns Starfish, a tropical species that possesses long, sharp, venomous spines capable of delivering a painful and toxic sting requiring medical attention. Even non-venomous species can have rough or calcified skin that may cause minor scrapes or irritation.
Any interaction with marine life carries a risk of bacterial transfer, as sea stars harbor common marine pathogens. After any direct contact, thoroughly wash hands with soap and fresh water to minimize the risk of infection. When observing a sea star, keep fingers away from the central underside of the animal, where its mouth is located.