Barnacle: Difference between revisions

[[Barnacles]] can be found on just about any beach in the world. These marine animals are sessile, filter feeders, and they are most commonly known for being attached to rocks and hulls of ships, and for cutting up skin when stepping on them.  They are a major problem for sailors when enough barnacles cluster to the ship and makes the ship heavier and less aerodynamic.  Also because of an extremely strong adhesive they are difficult to remove from just about any surface.  Though they are known as a nuisance they do have some good qualities.  For one they help to filter out the water by feeding on the detritus and plankton in it.  This helps the water to stay clean and clear.  [http://museumvictoria.com.au/crust/barnbiol.html]   

[[File:Barnacle_anatomy.jpg|left|225px]]There are several parts that make up a barnacle.  The outermost layer of a barnacle is its shell.  The shell of the adult barnacle is usually composed of four to eight calcareous plates which can form different shapes depending on the species of barnacle.[http://www.mesa.edu.au/friends/seashores/barnacles.html] This hole is also covered by two calcareous plates which can pull back to reveal the inside of the barnacle.[http://museumvictoria.com.au/crust/barnbiol.html]  These plates will grow and expand by adding more material to itself.

These plates are operated by several sets of muscles.  The scutal depressor muscles, the scutal abductor muscle, and the tergal depressor muscle are used to open and close the two plates that cover the opening to the barnacle.[http://webs.lander.edu/rsfox/invertebrates/balanus.html]  

Immediately inside the Barnacle are six legs that are used for three purposes.  These legs or cirri are usually formed in a feather like shape and have tiny sensory hairs called setae that cover the cirri.[http://invertebrates.si.edu/crustaceans.htm] These legs are used for filter feeding, are the main source of response, and they are used for respiration in class cirripedia.[http://www.waterencyclopedia.com/Ce-Cr/Crustaceans.html]  When used for feeding the legs are extended into the water by the barnacle in order to catch whatever food it can.  The legs are then retracted and whatever particles the legs have caught are brought to the mouth..[http://invertebrates.si.edu/crustaceans.htm]  They are also used as the sensory organs of the Barnacle.  The tiny sensory hairs on the cirri detect danger and water level in order to tell the creature whether to open or close the two calcareous plates at the top [http://www.cb1.com/~john/research/barnacle.html]

The digestive system is composed of the [mouth], [esophagus], [stomach], [small intestine] and [anus].  The digestion process looks something like this:  After the Barnacle's cirri feed the food to the mouth it goes down a short esophagus.  After flowing through the esophagus it ends up in the stomach, where it is stored for some time.  It then goes down the small intestine where the nutrition is absorbed.  After the nutrition is absorbed the waste is then excreted out the anus, which is then filtered back out into the ocean.[http://webs.lander.edu/rsfox/invertebrates/balanus.html]  

The first step of the process is fertilization.  The barnacle will release sperm into the ocean through its penis.  The sperm will travel until another barnacle consumes the sperm.  When the sperm reaches another barnacle it is delivered to the mantle cavity to fertilize the eggs that are stored there.  In some species the barnacle will extend its extremely long penis to another barnacle and inject the sperm to fertilize it.[http://webs.lander.edu/rsfox/invertebrates/balanus.html]  

Barnacles are marine animals that live in both shallow and tidal waters.[http://en.wikipedia.org/wiki/Barnacles]The Barnacles are also suspension feeders that are sessile and feed on detritus and plankton.  They use their net-like cirri to reach out into the water and back in a constant drum-like rhythm in order to capture food.  [http://www.absoluteastronomy.com/topics/Barnacle]  They can be found anywhere in the intertidal zone on just about any coast in the world.  They can be found just about anywhere.[http://www.wildsingapore.com/wildfacts/crustacea/othercrust/ciriipedia/cirripedia.htm]  They can also be found glued to just about any surface.  These surfaces include ships, rocks, whales, and docks.[http://library.thinkquest.org/J001418/barnacles.html]