Why Do Barnacles Attach to Turtles?

Did you know that barnacles need a hard surface to thrive, and cannot live underwater on their own? Yet, being inherently marine animals, they spend most of their time in or around water. 

So how do they do that? By attaching themselves to turtles and other sea creatures. Read on to learn how this interesting natural phenomenon works. 

What Are Barnacles? 

A highly specialized group of crustaceans, barnacles are somewhat related to lobsters, crabs, and shrimps. They are grayish-white in color and are sensitive to dryness or cold water. 

There are more than 1,400 species of barnacles found among marine life around the world. And by definition, almost all of these sticky little crustaceans are immobile. 

However, since barnacles cannot survive underwater by themselves, they need some assistance. Therefore, as soon as barnacle larvae mature, they start looking for an anchoring place. 

The young barnacles travel on the ocean currents as they search for a location with good water flow as their preferential habitat. More often than not, this happens to be a marine animal that keeps moving. 

They commonly attach themselves to creatures such as lobsters, crabs, sea snakes, whales, and sea turtles. In general, once the barnacle chooses a surface, they will spend the rest of their lives on it. 

How do Barnacles Attach to The Turtles? 

If you’ve ever had to maintain a sea vessel, you will certainly be aware that removing barnacles isn’t an easy job. This is why they are referred to by their slang name, “crusty foulers,” by some boaters. 

Barnacles secrete fast-curing cement that allows them to stick to pretty much any surface they come into contact with. 

This cement has an adhesive strength of 22 to 60 pounds per square inch and tensile strength of 5,000 pounds per sq inch, which makes it one of the most powerful glues found in nature. 

In fact, this glue is so strong that scientists are actively trying to find a way to make it suitable for commercial use. 

This glue is the main factor that allows barnacles to maintain their sessile lifestyle. As a result, they can go through their entire life without having to exert a lot of energy to move and find food. 

Why Are Turtles an Ideal Surface for Barnacles? 

Though barnacles will attach themselves to a variety of sea creatures, they generally prefer hard surfaces as their permanent habitat. However, they also need something that is constantly on the move. 

This makes turtles an ideal living surface for these crustaceans. Hence, if a turtle comes close to a barnacle when the latter is in its larval stage, the barnacle would attach itself to the hard surface.

What Do Barnacles Feed On? 

Barnacles are known to be suspension or filter feeders. Filter feeders eat by sweeping food from water and putting it into their mouths. They use their feet for this purpose. 

This is why, when attached to a boat or a ship, you’d find the barnacles on the underside. The position allows them to pull food from the water, which wouldn’t be possible if they were attached to the top.

However, since turtles float under water, barnacles don’t have this issue. They can comfortably live on the top of their shell and have their meals whenever the turtle decides to go for a swim. 

Their feet, also known as cirri, somewhat resemble a fan. This makes it easy for the barnacles to trap more food from the water, as they can’t exactly control when they get to have their next meal. 

This is also a reason why barnacles prefer residing on marine animals over boats and ships; marine animals are more likely to stay on the move and take them to areas where they can find food. 

Additionally, moving waters make it possible for the tides to bring food to barnacles even when the animal is in a mobile position, as long as they are on or near a water body. 

When there is a tide coming their way, barnacles will open their mouth and grab as much food as possible using their legs. Soon afterward, they close their operculum to save water. 

When it comes to their dietary choices, barnacles are known to be omnivores. This means that they eat both plant and animal matter. 

One of the most common things that barnacles have been observed to feed on is plankton. These are the tiny organisms that float on the surface of the water and are crucial to the reef ecosystem. 

Eating planktons provides the barnacles with enough proteins, vitamins, and minerals in their bodies, and supports their growth. 

In addition to that, feeding on enough plankton provides the barnacles with more energy to cling to the surface. 

They have also been observed to feed on algae, which provide them with minerals and calcium. Calcium is crucial to maintaining the health of their shells and cirri. 

Another thing barnacles commonly feed on is dead matter from other animals and plants. Depending on what species this matter is coming from, it can provide the barnacles essential nutrients, like fat and protein. 

Barnacles hibernate during winters, and therefore do not feed during this period. Having enough protein in their diet is necessary for their survival through the cold season. 

Does That Make Barnacles a Parasite? 

By definition, you may feel that barnacles are parasites since they do survive on other animals. However, in order to be classified as a parasite, they need to survive on the food of their host. 

That’s not the case with barnacles. 

The majority of the time, a barnacle would work for its own food. They only need a strong, moving surface as a place to live. 

That being said, there are barnacles that have shown some parasitic behavior, especially when attached to a crab. 

Due to the crab’s shape, a barnacle can enter its shell. In case this happens, the barnacle would start changing its behavior and start living on the diet of the crab. 

What’s worse is that the crab would assume that the barnacle is their own “baby” and start taking care of it. This makes a bad living environment for both the crab and the barnacle. 

However, the same is not the case with turtles. It can be challenging for a barnacle to penetrate through the shell of a turtle, making it more probable that it’d survive on the surface. 

There have been instances of a barnacle drilling through the shell of a turtle, but that is a very rare occurrence. 

 Therefore, a barnacle doesn’t exactly qualify as a parasite when it comes to turtles, since they find their own food. 

Are Barnacles Dangerous For Turtles? 

If you’ve ever seen a video of a sea turtle with a number of barnacles attached to its shell, your first thought may have been, “That must be painful!” However, that’s seldom the case. 

The barnacles don’t actively harm the turtle. Remember, not only are they looking for a place to survive, but they also want this to be their habitat for the rest of their lives. 

In a way, the barnacle’s life depends on the health and longevity of its host. Therefore, it would be impractical for them to do any active harm to the host. 

If the barnacle was hurting the turtle in any way, evolution would have taken over and fixed the issue over the past few centuries. 

So it is safe to say that the turtle isn’t in any pain or distress if a barnacle is attached. However, the problem begins when a large number of barnacles attach themselves to a single turtle. 

Despite the hard shell of the turtle, an excessive infestation of barnacles can become a health concern. This is when the likelihood of the barnacle drilling through the shell increases. 

As a result, they can infect the turtle and make them weak and lethargic. A wild turtle in such a scenario would likely die. 

If this happens in a marine life center, a proper rehabilitation procedure needs to be performed to safely remove the barnacles from the turtle before returning them back to the water. 

Final Words

If you ever notice barnacles on a turtle, it is recommended to leave them alone. In most cases, trying to remove them can be more harmful to the barnacle as well as the turtle. 

Additionally, you may not have the proper skill and experience to safely perform the procedure. Keep in mind that both turtles and barnacles have evolved to thrive in such a situation. 

However, if you notice that the barnacle infestation is harming the turtle, consider reporting it to the relevant local authorities as soon as possible. 

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