Starfish, also known as sea stars, are fascinating marine animals that inhabit coastal areas around the world. Their unique shapes and behaviors have captivated people for ages. When exploring the seashore, you may be tempted to pick up a starfish to examine it more closely. However, there are very good reasons why you should not touch a starfish if you happen to come across one.
What is a starfish?
Starfish belong to the phylum Echinodermata and the class Asteroidea. There are around 2,000 species of starfish worldwide. They have a central disc shape with usually five arms radiating out, although some species have more. The underside of their body has hundreds of tiny tube feet that they use to move around and cling to surfaces. Their mouth is located on the underside of the central disc.
What do starfish eat?
Starfish are carnivorous and use their extrusive stomachs to eat prey such as clams, oysters, and mussels. They envelop their stomach over the hard shells of prey to digest the animal inside. Some species eat sponges, coral, and fish debris. Their diets depend on their habitat and species.
Where do starfish live?
Starfish live in many marine habitats including tidal pools, rocky shores, sandy bottoms, coral reefs, and deep ocean floors. Different species thrive in different areas depending on environmental factors like temperature, salinity, and available food sources.
Why should you not touch a starfish?
There are several important reasons why you should not touch or handle a starfish if you see one on the beach or in the water:
It can damage or kill the starfish
A starfish’s body is very delicate. Their skin and tube feet are sensitive and touching them can cause significant harm. Picking up a starfish removes it from water which can lead to dehydration, overheating, and death. Their arms can also be easily damaged or broken off. In some cases, a starfish can regenerate a lost limb after several months, but this takes a huge amount of energy and can compromise their health and survival.
Your hands have oils, sunscreen, and lotion that can poison starfish
Human hands naturally have oils on them that are toxic to starfish. Sunscreens, lotions, and any other products on your hands can also poison them. When you pick up a starfish, these substances transfer directly onto their sensitive bodies. The chemicals disrupt their systems, sometimes fatally. Even brief handling with clean hands can remove their protective mucus coating.
You can spread diseases between starfish
There are bacterial, viral, and parasitic diseases that can infect starfish populations. If you touch one starfish and then pick up another, you risk spreading contagions between them. Outbreaks of disease can devastate groups of starfish, especially in crowded tidal pools. Some illnesses also pose a minor risk to human health.
Handling causes severe stress
Being handled by a human is extremely stressful for a starfish. As a defense mechanism, they can cast off their arms to escape a perceived threat. This is called autotomy. Losing an arm taxes their health and energy reserves. The stress of being picked up can also compromise their immune systems and make them more susceptible to disease.
It disrupts their natural behaviors
Touching a starfish removes them from their habitat which interrupts normal behavior like hunting, hiding from predators, resting, etc. After being handled, the starfish will need to expend energy to return to safety instead of fulfilling its natural needs. Constant disruption can lead to starvation and vulnerability.
You could get injured
Although starfish look harmless, some species have venomous spines or pedicellariae to deter predators. Pedicellariae are tiny pincer-like organs on the skin. Handling the wrong starfish could result in a painful sting or puncture wound. In some cases, the venom causes nausea, muscle spasms, and respiratory distress requiring emergency care.
How to observe starfish without touching
If you want to admire starfish, there are safe ways to do so without touching them:
Look in tide pools
Tide pools offer an excellent glimpse at starfish and other intertidal life. Spotting starfish in shallow water allows you to notice details like colors, patterns, and behaviors from a safe distance. Just be careful not to step in the tide pool or disturb the delicate ecosystem.
Go tidepooling with a guide
Join an educational tidepooling tour led by a naturalist guide. An expert can point out camouflaged starfish species and share facts you might otherwise miss. Guided tidepools help raise awareness and ensure no animals are accidentally handled.
Visit an aquarium’s touch tank
Many aquariums have special touch tanks or intertidal exhibits featuring starfish and other species adapted for hands-on interaction. These animals are monitored by trained staff to ensure their health and safety for public viewing. Touch tanks offer a rare opportunity to feel a starfish without negative impacts.
Use photography to get closeups
Taking photos is a great non-invasive way to admire starfish and sea life. Zooming in with your camera allows spectacular closeups that reveal details invisible to the naked eye. Photography can also help document species diversity without any handling.
Observe from docks or the shore
Simply watching starfish and other marine organisms from piers, docks, or the shoreline provides enjoyment without disturbance. Be cautious of waves and slippery surfaces. Avoid walking on intertidal habitats like coral and seaweed beds where starfish live.
Fascinating facts about starfish
Starfish aren’t fish
Despite their name, starfish aren’t related to fish at all. As echinoderms, they are more closely related to sand dollars and sea urchins than bony fish. Their name comes from their star shape, not any biological classification.
They don’t have blood
Starfish circulate nutrients through their bodies using seawater instead of blood. A delicate system of canals and pumping structures moves water throughout their bodies to nourish tissue.
Their eyes are on their arms
Starfish eyespots are located on the tips of their arms, allowing 360 degree vision to detect food and avoid danger. Some species have up to 1,000 eyespots, while others have none at all.
Starfish eat with their stomachs outside their bodies
To feed on hard-shelled prey like clams or oysters, starfish eject their stomachs from their mouths onto the prey to externally digest it before pulling the food back into their bodies.
They can regenerate lost limbs
If a starfish loses an arm, it can slowly grow back over several months. Some species must have the central disc and a portion of the arm present to regenerate, while others can regrow an arm from just a small arm segment.
Starfish move with hundreds of tiny tube feet
On the underside of each arm, starfish have hundreds of tiny tube feet that use suction to grip surfaces. They use a synchronized wave motion with these tube feet to slowly creep along. Some starfish species can move up to 6 inches per minute.
Unique defense mechanisms
In addition to autotomy or self-amputation, starfish have evolved other defensive tactics:
Inflating their bodies
Some starfish can inflate themselves with water to make them harder to dislodge from rocks. This inflation makes them appear larger to predators.
Poisonous saponins
Several starfish species produce toxic steroid-like compounds called saponins. These chemicals deter predators and may cause sickness if ingested. Ochre sea stars store saponins in their pedicellariae.
Startling color displays
Vibrant colors warn potential predators that some starfish species are toxic or distasteful. Flashy patterns also help camouflage starfish against coral reef and rocky habitats.
Venomous spines
The spines on certain starfish contain venom that causes severe pain or sickness when stabbed into a threat. Crown-of-thorns sea stars have famously sharp venomous spines.
Rapid escape responses
Some starfish respond to disturbance by quickly crawling away to find shelter. Species like the spiny star Astrosarkus can escape danger by swimming briefly.
Ecological importance
As predators and prey, starfish fill vital ecological niches:
Keystone predators
In some marine communities, starfish act as critical keystone predators, meaning they exert substantial influence over the rest of the ecosystem. Removing them causes dramatic population shifts in prey species.
Control mussel and shellfish abundance
Certain starfish are ecologically important for controlling mussel, oyster, and other shellfish numbers. Without starfish predation, these prey species can explode in population size and disrupt the balance of their habitats.
Nutrient cycling
Starfish facilitate nutrient cycling in marine environments by eating and digesting plant and animal material, then releasing those nutrients back into the ecosystem through their waste.
Prey for fish, birds, and crustaceans
As prey themselves, starfish are an important food source for species like fish, sea otters, shorebirds, and crabs. Loss of starfish populations indirectly impacts these predators.
Scavengers
Some starfish act as important scavengers by consuming dead animals and debris on the seafloor, helping keep ecosystems clean and healthy.
Starfish in captivity
While stunning in home aquariums, keeping a starfish as a pet is very challenging:
- Require large, highly specialized saltwater tanks
- Only eat live foods like shellfish, often inconvenient for owners
- Easily stressed by improper water conditions
- Lack of stimulation and space compared to the ocean
- Potential to introduce diseases or parasites to wild starfish if released
For these reasons, it is better to appreciate starfish in their natural habitats when possible. Many aquariums successfully keep starfish using expert care.
Threats facing starfish
Sadly, some starfish species now face serious threats to their survival:
Habitat loss
Coastal development, pollution, destructive fishing practices, and climate change are destroying sensitive marine ecosystems vital for starfish. Loss of tidepools and coral reefs removes their shelter and food sources.
Overpredation
Population explosions of predatory crown-of-thorns sea stars have caused mass die-offs of coral reef starfish species in areas like the Great Barrier Reef. These outbreaks may be influenced by human activities.
Ocean acidification
Rising ocean acidity due to increased atmospheric carbon dioxide impairs the development of larval starfish, limiting successful reproduction. Other acidification effects likely impact starfish respiration, skeleton formation, and more.
Wasting disease
A mysterious wasting disease has devastated populations of sunflower sea stars and other starfish species along the Pacific coast of North America since 2013. The exact cause is still unknown but potentially linked to climate change.
Invasive species
Non-native predatory seastars like Asterias amurensis from Asia are invading Australian waters and threatening native starfish already at risk from coral bleaching and habitat loss.
Conservation efforts
Several initiatives are underway to protect vulnerable starfish populations:
Habitat restoration
Restoring damaged coastal ecosystems, removing invasive species, and cutting pollution can help restore starfish habitat and food sources.
Breeding programs
Aquariums are pioneering captive breeding programs for at-risk starfish species to boost their numbers for reintroduction to the wild once threats are mitigated.
Fishing limits
Restricting destructive bottom trawling and catch limits on predator species helps reduce indirect starfish deaths and damage to ocean floor habitats.
Citizen science
Public monitoring programs allow people to report starfish sightings and disease outbreaks to researchers tracking populations and managing recovery efforts.
Legal protections
Laws like the US Endangered Species Act now officially protect certain critically endangered starfish to limit further harm and mandate recovery planning.
Conclusion
Starfish are fascinating echinoderms that play vital roles in marine ecosystems and captivate shoreline explorers. However, there are very compelling reasons not to touch or handle them if you encounter them in the wild. Human contact can damage their sensitive bodies, spread disease, interrupt their behaviors, and potentially be dangerous. Appreciating their beauty from a distance and respecting tidepool inhabitants ensures we minimize our footprint. Several concerning threats now jeopardize some starfish populations, making our responsible stewardship all the more critical.