Barnacle

Barnacles are few exclusive Marine creatures that are found in shallow water. They are greyish white, sticky organisms which are often found attached to hard surfaces in seas.  They are commonly found organisms and can be spotted on rocky shores, they are exclusively studied by scientists as they show bizarre characters. At present, there are about 1,000 different species of barnacles. They have four different active swimming stages. They are generally sessile creatures, which means that they cannot move from one place to another and are immobile. They belong to the arthropod family. 

Hence barnacles are close relatives of lobsters and crabs. The infraclass of barnacles is called Cirripedia. The name Cirripedia is originally derived from the Greek word "Cirripedia" which actually means curl footed. The exclusive study of only Cirripedia is called Cirripedialogy. Today let's take an overview of these bizarre creatures and understand more about them. 

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The General Functioning of a Barnacle and its Body Structure

Although there are several types of sea barnacles, all of them share a few general characteristics. Let us take a look at these general characteristics before we dive deep into the different types of barnacles. These are generally found in clusters of structures that are temporarily attached to a hard surface. The attachment between a barnacle and the hard substrate is done using a stalk. Some free-living barnacles are attached to a hard substance by the means of a cement gland. A ring of plate-like structure surrounds the barnacle on the sides of their stalk. An adult barnacle also possesses an antenna on its head. A barnacle also has eight pairs of limbs, these long and hairy limbs are termed as "cirre". The functionality of these limbs is to filter food like plankton and water, and then drive these food items towards the mouth. 

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Barnacles have no so-called heart, they have a sinus near their esophagus which performs a similar function to that of the heart in the human body. The sinus pumps blood throughout the barnacle's body using muscular activities. No designated gills are found in barnacles to absorb oxygen from water. However, the inner membrane of their limbs performs a similar function. The inner membrane has tiny pores which are capable of absorbing oxygen from water. 

The main sensation that barnacles process is touch. Barnacles can feel touch using their limbs. Barnacles have hair-like structures on their limbs which are highly sensitive. Barnacles also have three photosensors, which are used to sense daylight and help maintain the biological clock of barnacles. 

The General Lifecycle of A Barnacle 

Every animal has a life cycle, for instance, butterflies have a vivid life cycle, starting from being a larva to becoming a beautiful butterfly. Similarly, barnacles have a life cycle too. 

1. Nauplius

Nauplius is the first life stage of a barnacle. The fertilized egg of barnacle hatches and a nauplius is created. The nauplius has only one eye and head. The formation of the thorax and abdomen is not finished yet. 

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2. Cyprid

The cyprid stage is the second and the last larval stage of a barnacle. This stage lasts for about a few weeks. The primary goal of this stage is to find a suitable place where the barnacle can settle. This is because adult barnacles are sessile and need a designated hard surface to settle on. By the time this stage is reached, the antennas of the barnacle are fully developed. The cyprid explores different hard surfaces available in its surroundings by using these antennas. Surfaces are assessed based on texture, the presence of harmful chemicals, wetness, and colour. 

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3. Adult Stage 

Once the barnacle has cemented itself on a hard surface, adulthood is reached. The barnacle is now ready and has a fully developed body structure. It fixes itself onto a hard surface and continues to live on it. 

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Interesting Myth Behind Barnacle Goose 

Well, barnacle geese are in no way related to barnacles. However, they have an interesting story behind their naming. The barnacle goose was first found in the twelfth century in Europe. Gerald of Wales, a popular historian, spotted these birds hanging upside down to timber. They were attached to Timber structures which were comparable with barnacles that attach to its host hard surface. Hence Gerald of Wales drew this comparison and resultantly the name barnacle goose was coined.

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Types of Barnacles

1. Acorn Barnacles

Acorn barnacle is one of the species of barnacles that are commonly found in the sea. Barnacles and whales have always shared a special relationship. Barnacles and whales are connected as Acorn barnacles are a species of barnacles that grows on whales. Whale barnacles stay on the hard surface of the whale and passively filter food as the host whale moves through the water. The whale also uses barnacles as armour on its skin. The presence of barnacles forms an armour-like structure around them which helps them inflict higher damage on their enemy. Hence the relationship of Whales and barnacles is a symbiotic relationship since both these organisms are being benefited by their relationship. 

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2. Sea Turtle Barnacles

As we all know the turtle shell is one of the hardest substances found naturally in the environment. The shell of a turtle is just the perfect surface for a barnacle to grow and flourish. Just like how barnacles can grow on the surface of whales, they can also grow on the shell of a turtle. Barnacles are immobile creatures and hence finding adequate food is a challenging task for them. Hence, by settling on top of surfaces of motile creatures which move, barnacles greatly expand their reach to food and make it easier for them to grab food for themselves. Hence, turtle barnacles are one of the most common types of barnacles found in the ocean.  Sea turtle barnacles have a much higher chance of survival than barnacles that settle on rocks. This is because barnacles on rocks are scissile and have limited access to food and oxygen. Once the food available in their reach is exhausted, they can easily perish. 

3. Barnacles on Crabs 

Certain breeds of crab also have a hard shell on them. There are breeds of crabs that swim in shallow waters as well. Gaining motility and shallow waters is the primary criteria for barnacles to choose a surface to settle on. Hence crab shells are hard enough a perfect host for housing barnacles. Hence, barnacles can easily settle on the crab shells and move around as the crab moves. Resultantly it becomes much easier for the barnacles to capture food and expand their reach. By moving with the crab they can grab more planktons to feed on. Hence barnacles and crabs are another common phenomena. 

4. Barnacles on Ships

Lots of trading in this world happens through ships. Ships are one of the most common objects found in the ocean. There are several kinds of ships, rusty container ships that carry around goods from one country to another via sea are perfect hosts for barnacles. Large container ships move at a slow pace through the sea and have a hard surface on which barnacles can easily settle and thrive. Barnacles are often found on rusty ships, the reason again being the same as the reasons listed above. Container ships are perfect as they are hard enough for the barnacle stalk to stick with. As the container ships move, the barnacles move along with them. Hence this makes these sessile creatures motile and expands their reach to grab food and oxygen. 

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5. Goose Barnacles

Goose barnacles are another breed of barnacles found in the sea. Also known as Gooseneck barnacles, possess a long fleshy system and black neck. On top of the stem, there is a chalky white shell. Goose barnacles are popular because they are one of the edible breeds of barnacles. In many places of the world, goose barnacles are a much-enjoyed delicacy. In fact, in countries where goose barnacle is a part of the culinary culture, people wait for ships to come back from their voyages. This is because often when ships sail in the ocean, goose barnacles cling to their hard surface. 

Upon their return, people take the goose barnacles and sell them in the markets. They are often looked upon as a money mill because they are rarely found and are truly relished by the local people. Goose barnacles are prepared delicacies in European countries such as Portugal and Spain. They are seen as an Elite food and are generally made for treats and celebrations. They are highly expensive as well as finding them is a rare phenomenon. 

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Sexuality of Barnacles

Barnacles are hermaphrodites. This means that a barnacle can mate with another barnacle irrespective of their gender. Barnacles can also exhibit the phenomenon of self-fertilization by fertilizing their own eggs. However, this is a highly rare phenomenon. Hence eggs produced by one barnacle are likely to be fertilized by another barnacle. It generally takes around six months for barnacle larvae to fertilize. 

Amazing Facts About Barnacles

1. Barnacles are Believed to be one of the Oldest Surviving Creatures.

It is believed that they have existed for more than a million years. Over the years particles have shown some adaptations, but they remain unchanged for several centuries now and have existed in almost their original format for years. Although today seawater has become highly polluted and most of the marine life has been greatly affected, barnacles are known to have been affected the least. 

2. Barnacles are Originally Crustaceans.

Earlier it was believed by scientists that barnacles belong to the molluscs category and are closely related to snails. However, later on, studies proved otherwise. It was found that barnacles are originally crustaceans. They are actually close relatives of crabs and lobsters. They have a similar hard outer shell like that of arthropods and hence come under the arthropod family. 

3. Barnacles Eat Using their Legs.

Sea barnacles are known to eat using their legs. Yes, you heard that right! Doesn't it sound bizarre? Well, of course, it is. As we have already seen, barnacles are sessile animals and cannot move from one place to another. Hence they do not use their legs to move, moreover, they possess 8 pairs of legs. Resultantly they use their legs to swipe through water and guide food particles like planktons floating in the water to their mouths. They pass the water between their productive plates and close their plates to trap the food particles inside their mouth. 

Conclusion

Today we've explored and understood one of the most bizarre creatures found in the world. We've explored every aspect of this minuscule mysterious creature named Barnacle and understood their nutrition, reproduction, and lifestyle! Well, wasn't it an interesting journey?