How Long Can A Starfish Live Out Of Water?

Starfish, also known as sea stars, are fascinating echinoderms that inhabit coastal areas around the world. If you’ve ever been to the beach, you may have spotted their five-pointed radial bodies along the shoreline or in tidal pools.

A common question that beachgoers and starfish enthusiasts alike wonder is: how long can a starfish live out of water?

If you’re short on time, here’s a quick answer to your question: starfish can survive out of water for up to 8-9 hours if kept damp and cool. However, their survival time is much shorter in direct sunlight or dry conditions.

Anatomy Adaptations That Help Starfish Survive Out of Water

Tube Feet for Movement and Respiration

Starfish have hundreds of tiny tube feet underneath their arms that function in locomotion and gas exchange (helping the starfish breathe). When out of water, the tube feet prevent dessication by tightly gripping onto wet surfaces. This retains internal moisture.

The tube feet also enable limited movement on land to find water sources. According to University of California Museum of Paleontology, these tube feet can further pull in small amounts of oxygen from the air.

Central Disk for Moisture Retention

The starfish’s central disk stores water to prevent dehydration. Made up largely of marine water, the cushiony disk soak up surrounding moisture through the use of osmosis. American Museum of Natural History notes the starfish’s body is well-suited for maintaining water balance in the challenging intertidal zone environment.

Tough Exoskeleton for Protection

According to marine researchers, the starfish’s tough, spiny exoskeleton acts as a barrier, significantly slowing water loss. This protective outer covering is essential for the echinoderm’s survival when briefly exposed during low tides.

Starfish can still lose some moisture, however, through pores in the exoskeleton required for respiration.

Factors That Affect How Long Starfish Can Stay Alive Out of Water

Exposure to Air

Starfish breathe through tiny structures called papulae on their body surface that absorb oxygen from water. When exposed to air, these papulae dry out quickly, making it impossible for the starfish to breathe (1). Most starfish will die after just a few hours out of water without access to oxygen.

Direct Sunlight and Heat

Another danger of being out of the ocean is direct sunlight. A starfish’s skin is very sensitive, and exposure to UV radiation from the sun can easily damage or kill the animal. Additionally, on hot days, starfish can rapidly overheat since they lack internal temperature regulation.

Temperatures over 30°C will quickly become fatal without the temperature moderation of water (2).

Lack of Moisture

Starfish need to keep their skin moist in order to breathe, feed, and move properly. When removed from the water, the starfish will quickly begin to dry out and will be unable to perform these basic functions.

Thick-skinned starfish species like the ochre sea star can survive longer without water than species with thin skin such as the brittle star (3). But all starfish need water to survive long term.

Starfish Species

Some starfish species are hardier than others when out of the water. Here is a comparison of survival times for some common starfish species (4):

As shown, the hardy ochre sea star (found along the Pacific coast) can last over a day out of water, while more delicate species like the brittle star will perish after just a few hours. Genetics play a key role in desiccation and sun tolerance between the hundreds of starfish species.

Tips for Handling Starfish Out of Water

Minimize Air Exposure Time

Starfish can survive for a brief time out of water, but the clock starts ticking as soon as they leave their aquatic environment. According to marine biologists, a starfish’s survival time is very limited without water.

After just a few minutes, the starfish’s body will start to dry out, putting its life at risk. So if you take a starfish out of the tide pool for observation, make sure to minimize air exposure and return it to the water within 1-2 minutes.

Keep Them Cool and Wet

While handling starfish temporarily out of water, it’s crucial to keep their bodies cool and moist. Use a container filled with seawater to hold the starfish. The temperature should match the tide pool environment.

Avoid direct sunlight exposure as the heat and dryness will quickly dehydrate the starfish. You can also drape wet paper towels or cloths around the starfish. The evaporation will create a humid microclimate to prevent drying.

Be Gentle When Handling

A starfish’s body is very delicate and fragile. According to marine conservation groups, their arms can be easily damaged or broken if handled roughly. So when picking up starfish, do so gently with both hands cradling the underside.

Avoid grasping the arms tightly or bending them backwards unnaturally. Also ensure any observation surface has a soft cover to prevent abrasions to the starfish’s skin surface. Return them to the water gently without tossing or dropping.

With extra care and precaution, starfish can temporarily survive short duration outside water for observation and research purposes. But extended air exposure will threaten their health and survival. If planning to remove starfish from their aquatic habitat, one should adhere to responsible marine wildlife handling guidelines as advised by conservation authorities.

Conclusion

Starfish are remarkable echinoderms with special adaptations that allow them to survive for limited periods out of water. While they can stay alive for 8-9 hours if kept moist and cool, direct sunlight, dryness, and mishandling can shorten their survival time dramatically.

If you ever come across a starfish on the beach, remember these key tips for handling them safely out of water – minimize air exposure, keep them cool and wet, and be very gentle. With appropriate care, you can help ensure starfish make it back to the ocean or tide pool to continue thriving in their aquatic habitat.