Macbeth Assessment Essay Example for Free

Macbeth Assessment Essay Macbeth written in 1606 has proven to be one of Shakespeares most successful and popular plays. It wasnt just the plays that were popular William Shakespeare born 1564 is the most famous play writer in the world. He was born in Stratford upon Avon. He wrote 34 plays, Macbeth being just one of them. There are many reasons why Macbeth has proven to be so popular. It is the third shortest play written by Shakespeare, it is fast moving including death, murder, deception, and betrayal. The play follows the story of a man who was desperate for power and turns to murder to get his own way. It has conserved its title as an exceptional play as it appeals to audiences both today and in Shakespeares time, by including factors that appeal to everyone. In Shakespeares time people would be intrigued by the supernatural, as they were xenophobic, they took a dislike towards the witches. They didnt understand them even today when we know a little more about the supernatural it is still a topic people would like to know more about. The play makes you want more. You want to find out if he was a good king or if he would really murder his best friend. It is an unpredictable play you dont know what is going to happen. Theatre going was very popular in the 1600s because not only was it for the rich the poor could enjoy the entertainment as well. Many people enjoyed the magic of the theatre, thats what made it such a success. The globe built in 1599 was one of the first theatres in London, it could seat over 3,000 people but sadly tragedy struck in 1613 when the great fire of London burnt down the theatre along with many other famous landmarks. It was a great loss in everyones eye, so a year later the globe was replaced. It cost à ¯Ã‚ ¿Ã‚ ½1,400 to rebuild. It didnt take long before the theatre had paid for its self as it was so popular. The poor people would sit in the pit they would only have to pay 1p but if it rained they would get wet, as there was no shelter. The rich people could sit around the sides where they would be able to see everything as the seats were tiered along the sides they were sheltered from the cold. They would have had to pay around 10p for their seat. As a variety of people attended the play would have to cater for a range of people. Not a play for the rich or poor. If the king didnt approve of they play he could stop the performances. Shakespeares plays were clever they contained blood guts and gore. The monarchy and the political situation at the time had much to do with why the play had proven to be so popular. King James the first was new to the throne, as Elizabeth had died. Elizabeth was a popular queen where as James the first had shown to be very disliked. They worried what king James would be like on the throne they were right to be worried King James was evil he burnt and tortured Catholics. The declining catholic population soon grew to hate him and in 1605 a plot was taken against him in hope he would die. Guy Folkes attempted to blow the house of parliament up in The gun powder plot fortunately for the king he was unsuccessful. He was later executed. A year later when Shakespeare was writing Macbeth he had to be very careful on what he included. If James the first did not like the play and took offence to it then he could have Shakespeare killed. Shakespeares presented the play in good light. He displayed Duncan the king as a good king whom people loved, James would have liked this as he thought it portrayed himself but really Shakespeare was showing James to be Macbeth. The play showed a warning if a man killed the king he would suffer a fate as bad. The main theme of the play shows a man who is led to despair by his controlling wife. He starts as a loyal soldier serving his king to the very best. Due to his service he was made Thane of Cowdor, but that was not enough for him and his power mad wife. They thought of an evil plot to kill the beloved Duncan. They arranged to kill him in his bed and make it look as if his own guards have killed him. They succeeded in their plot for greatness. Macbeth is crowned king. Duncans sons who would have been next to the thrown, but they fled as they thought they were suspects for the murder. Macbeth now had the taste for murder. He killed his best friend Banquo. Later he tried to kill Macduff a fellow soldier but was unsuccessful as Mac duff got away. Macbeth was mad by this and instead of trying to kill Macduff he killed his wife and children. How could a man be so cruel as he may have suffered the pain of a child being taken from his life. Macduff was on his way to England to fetch an army thousands big. Lady Macbeth went mad with guilt and killed herself. Once Macbeth heard news of the triumph against him he started to worry. He got ready for a fight he placed on his amour ready. When Macduff arrived they fought their way into Macbeths castle in Dunsinane. Macbeth fought till the very end until it became too much he suffered a soldiers death. The supernatural had a large role in the play Macbeth. Macbeth included the supernatural, as the audience then were scared and shocked by it. They were scared of witches as they thought of them as bad. So when the play Macbeth was written Shakespeare included witches in the very start. This would have shocked the audience making them interested in the play from the very start. They would want to know what happened to them. Audiences now would be curious to see the supernatural and how the witches act. The witches cropped up several times in the play to keep the audience watching. The witches open the play when shall we three meet again, in thunder, lightning or in the rain? When the hurly burlys done, when the battles lost and won, that will be the set of the sun where the place upon the heath Macbeth is a very fast moving play, which included a lot of action. The play is short, it is so fast moving to keep the audiences attention. I think the action and length were quite important to an audience. If the play were long and lacked action the play would be unpopular and found boring. Plays had to appeal to everyone it would be important to keep them interested and as there would be peasants viewing they would have to cater for them. The plots would have to be quite straightforward so the peasants could understand. The main events in the play link with each other. The witches have an important role in the play on the heath in act 1 scene one and again in act 1 scene 3. They tell Macbeth and Banquo their future. The next important scene is Act 1 scene 5 when Duncan comes to stay with Macbeth to celebrate Macbeth becoming the Thane of Cowdor but sadly Duncan is brutally murdered in his own bed. Macbeth is forced to do the deed by his crazed wife. Then Macbeth is crowned king. The next important scene is when Macbeth gets Banquo killed and Banquos ghost comes to haunt him. Lady Macbeth tries to make excuses to cover his moments of madness. She tells the people not to leave, as this will offend him. Dray you keep seat. The fit is momentary upon a thought. He will again be well. If much you note him you shall offend him and extend his passion feeds and regard him not. The witches then appear again in act 4 scene 1. This time the witches didnt find Macbeth, Macbeth went to find the witches. He wanted to know more. So the witches tell Macbeth in words, which have a double meaning. This makes Macbeth thinks he is going to rule as king for a long time. Macbeth next tries to kill Macduff but is too late Macduff is already on his way to England to fetch an army to kill Macbeth. Then Malcolm can return as the rightful king. In rage Macbeth kills Macduffs wife and children. Meanwhile his own wife is going mad with guilt. She thinks she has a spot of Duncans blood on he hand, which she cant wash off. This time lady Macbeth has turned out to be the one with feelings instead of being callas. She had always called Macbeth a coward for showing signs of feeling Are you a man? he often tries to prove himself. What man dare, I dare Lady Macbeth becomes so deranged she kills herself. Then we meet the biggest scene, act 5 scene 3 at Dunsinane castle. Malcolms army fight there way into Macbeths castle to return the rightful king to the thrown. Many play writers would have included guts and gore to surprise the audience. If all plays were written about love and everything was perfect plays would become boring. Showing guts and gore with lots of action would keep the audiences interested. The technology back then wasnt that good not compared with today, but audiences back then would be impressed by Shakespeares use of trap doors and fake blood. The trap doors would be used for the witches and Banquos ghost to appear and disappear. This would reflect the power of the witches . They may have lowered Banquos ghost down on a rope to make it look as if it was floating. Many of these effects are still used today while doing performances of the play. The goriest bits in the play would be the murder scenes. Especially the scene with Duncan they would have used a lot of fake blood. Macbeths character changes quite significantly during the play he starts off as a loyal soldier dedicated to his king. He changes after his first meeting with the witches, once he knew his destiny he would do anything to get it as soon as he could. The witches told him he would be thane of Cowdor, and then he would be crowned king. His power mad wife often challenged his position. Why do you make such faces Macbeth showed feeling he didnt want to kill Duncan but callas Lady Macbeth drove him to it That I may pour my spirits in thine ear and chastise with the valour of my tongue this shows the power she had over him. Macbeth is good not evil yet I do fear thy nature, it is too full othmilk of human kindness Where as Macbeth is a gentle person. Lady Macbeth calls upon the spirits to make her evil enough to commit murder. Come you spirits that tend on mortal thoughts, unsex me here and fill me from the crown to toe top full of direst cruelty make thick my blood. The planning of Duncans murder was quite disturbing Lady Macbeth proves her callas feelings. The death is like a challenge. Art thou afeared to be the same in thine own act and valour as thou art in desire? She accuses him of breaking promises, that he isnt strong enough to accept the challenges wouldst thou have that which thou esteemst the ornament of life, And youre a coward in thine own esteem Macbeth braves himself as a man and accepts the challenge I dare do all that may become a man, who dares do more is none Lady Macbeth shows some feeling like the feeling she may once have had for her child I have given suck and know how tender tis to love the babe that milks me. I would, while it was smiling in my face, have plucked my nipple from his boneless gums and dashed the brains out, had I so sworn to you have done to this Her feelings soon turn evil as she says to Macbeth she would rather kill her child than break her promise. There was also many reasons why Macbeth shouldnt kill Duncan Hes here in double trust first I am his kings man and his subject, strong both against the deed then, as his host. Who should against his murder shut the door, not bear the knife myselfthis Duncan been so clear in his great office Macbeth was related to king, he was Duncans host. Duncan was a good king if Macbeth went ahead with the murder he could loose everything. It was worse to kill a king than anyone else. It was a huge sin against god. God chose who was to be king. Lady Macbeth made most of the plans for the murder, she controlled Macbeth. She told him when and how to commit Duncans murder. Macbeth said the dagger showed the way to Duncans room. The night for Duncans death was perfect. Crows searched the courtyard a sign of death. An owl shrieked anther sign that evil was in the air. When Duncan had retired to his room and the guards had fell asleep Macbeth brutality stabbed Duncan in the chest with a dagger. Macbeth returned out of Duncans room with the evidence in his hand. He refused to re-enter the room so lady Macbeth took them back in the room and put the blood of Duncan on the guards face to make it look like they had killed Duncan. Macbeth didnt prove to be a very good or popular king. Many people didnt respect him. He lost many of his friends especially his supposed best friend Banquo whom he had killed as he suspected Macbeth had killed Duncan. Later at one of Macbeth banquets, he started to talk to a ghost that wasnt even there. Lady Macbeth tried to cover it up. The second meeting with the witches as deliberate they told Macbeth words with double meanings. They told Macbeth he would be king until the wood moved. Macbeth thought he was safe, as wood couldnt move. The witches tricked Macbeth so the audience would see the witches as evil. Macbeth wasnt much better himself the most loyal thing he did while wearing the crown was suffer a soldiers death. He died a lonely man his wife had gone crazy and killed herself she jumped of the castles balcony. The audience views Macbeth would change at different points in the play. They would see him as a loyal soldier but then he turned evil but he still had some feelings he didnt want to kill Duncan he was bullied by his wife. After the dirty deal was done he never returned from the evils scheming. In conclusion I think Macbeth is a very good play. It is a fast moving play. Which includes love, deception, and murder. Aspects that would appeal to all audiences. The audience would be relieved that justice was done. By including these features I feel that Macbeth has proved the test of time as one of the best plays of all time. Many theatres today still make reproductions of the play. I think Shakespeare truly has lived up to his title as a great play writer.

The Cause And Effects Of Acid Mine Drainage Essay -- essays research p

The Cause and Effects of Acid Mine Drainage INTRODUCTION Imagine going fishing on a cool Autumn day, the trees are all different shades of orange, brown and red and the birds are singing their beautiful songs, but their is a serious problem because when you arrive at the river all plant and animal life are gone. This is by no means a recent phenomenon. This is due to the effects of acid rock drainage (ARD). This is a problem that has been occurring since ancient times, but it was not until the 1800's when fast growing industrialization and heavy mining that it caught alot of attention. Acid rock drainage is the term used to describe leachate, seepage, or drainage that has been affected by the natural oxidation of sulfur minerals contained in rock which is exposed to air and water. The major components of ARD formation are reactive sulfide minerals, oxygen, and water. Biological activity and reactions is what is responsible for the production of ARD. These reactions make low pH water that has the ability to mobilize heavy metals contained in geological materials with which it comes in contact. "ARD causes a devastating impact on the quality of the ground or surface water it discharges to. (Ellison & Hutchison)" ACID MINE DRAINAGE Within the mining process there are several sources that cause ARD. No matter what activities occur, ARD usually occurs when certain conditions are met. These conditions are the factors that limit or accelerate the release of ARD. The initial release of ARD can occur anywhere from a few months to many decades after the sulfide containing material is disturbed or deposited. ARD has been associated with mines since mining began. When ARD occurs due to the effects of mining it is called acid mine drainage, or AMD. The coal mining industry here in the eastern United States has been associated with a major source of AMD for decades. When water comes in contact with pyrite in coal and the rock surrounding it, chemical reactions take place which cause the water to gain acidity and to pick up iron, manganese and aluminum. Water that comes into contact with coal has a orange-red yellow and sometimes white color. The metals stay in the solution beneath the earth due to the lack of oxygen. When the water comes out of the mine or the bor... ...ansform organic material and nutrients.(Bastian 1993) Natural and constructed wetland have been used to treat wastewater. The first one that was ever constructed was in 1982. There are over 200 systems in Appalachia alone.(Bastian 1993) Even though this is safer for the ecosystem it is found that at most sites, chemical treatment is still necessary to meet efficient standards, but the costs of chemical treatment is greatly reduced with the initial biological treatment. Most operators find that the costs of the construction of the wetlands are made up within one year due to the money saved on chemicals. CONCLUSION In conclusion, acid rock drainage is a big problem all throughout the world due to alot of industrialization and mining. This is not only a serious problem around the world, it touches home here, especially here in Appalachia, but it seems to be under or getting under control with all the new regulations and standards the EPA is setting. Low pH and a high acidity level is harmful to us our wildlife and our plants. With the help of more education and more research it will not have to be a problem for our future.

Childrens Ailments In South India Health And Social Care Essay

IntroductionSuffering from minor complaints is the most frequent episode in childhood experiences. Fever is one of the main ailments every bit many as one tierce of all paediatric audiences in general practice.1 A survey indicated that parents still have a job to care the febrility in kids. Some parents believe that febrility is one of the diseases which may happen among their kids, instead than to be a mark or symptom of illness.2 In many states, the antipyretic medical specialty and other over the counter ( OTC ) medical specialties are normally used among parents to handle their children.3 Using ( OTC ) medical specialty among parents may be affected by their attitudes towards unwellnesss. However, it is deserving adverting that some old surveies show that parents ‘ cognition about febrility is still inaccurate. Most parents are confused about which medical specialty should be given to their kids to pull off the hurting and febrility associated with minor ailments.4 The common complaints of kids including concern, febrility, grippe, diarrhea and sore pharynx can be treated at place. Some minor complaints can be relieved with ( OTC ) medicines such as Paracetamol or other traditional redresss, without seeking for audience from general practicians or baby doctors. When a kid falls sick, the parents ‘ concerns are frequently influenced by their cognition of the complaints. Parents may acquire advice from the media, through household tradition, from friends and via other beginnings which affect their direction of the complaints. The construct of self-management in health care includes disease bar, selfdiagnosis, self-treatment and appropriate audience with wellness attention practicians. Within the context of kids ‘s complaints, the determination shaper will normally be the kid ‘s attention taker.5 A attention taker must be the parent or defender of the kid. In general, parents with higher degree of medical cognition are expected t o hold a better direction of kids ‘s complaints. This survey aimed to heighten the parents ‘ cognition about their kids ‘s unwellnesss and better their direction of handling their kids from minor complaints, in add-on to urge that wellness attention professionals should pass on with parents and do non project aside the latter ‘s beliefs about kids ‘s complaints.MethodThe survey design was cross-sectional survey. Data collected on a group of topics at one clip instead than over a period of clip. Parents were recruited to mensurate their medical cognition and direction degree to handle their kids ‘s complaints. This survey was conducted to place parents ‘ medical cognition on minor complaints refering their kids. The mark population of the survey was the ‘parents ‘ group regardless of age groups, ethnics, businesss, and societal position. The entire sample size of this study was 250 parents. Non-probability convenient trying method was used. Parents were recruited from the populace to reply our questionnaires. Harmonizing to the inclusion standards, the parents who were able to read and compose were included. Furthermore, parents who had child under 12 old ages old and agreed to take part in this study were included. The questionnaire was designed to measure the parents ‘ cognition about OTC medical specialties which are normally used to handle the minor complaints. In add-on, to research how the parents are normally manage the minor complaints. Most inquiries came from the old surveies related to parents ‘ self-medication and parents ‘ cognition about medical specialties. The face and content cogency were performed with wellness attention professionals before carry oning the study. SELF-administered questionnaire was used to roll up the information from the parents. Written informed consent signifier was obtained from the parents who were agreed to take part in the study. Parents were required to reply and finish the questionnaire on the topographic point. The questionnaire was designed to dwell of 3 parts. Part 1 was the demographic information of the parents, and Part 2 for look intoing the degree of medical cognition of parents about OTC medicines, whilst Part 3 was on the p arents ‘ ways of managing their kids ‘s unwellnesss. Data analysis had been done by the assistance of statistical package, the Statistical Package for Social Sciences ( SPSS ) Version 15.0. Frequencies of demographic information of respondents were tabulated. In order to mensurate the degree of medical cognition of parents and the direction of kids complaints, the mark of each respondent for portion 2 and portion 3 of the questionnaire was counted and analyzed. To cipher the entire Markss of different respondents, we used the marking method for different replies and actions.ConsequenceOut of the 250 distributed questionnaires, 240 ( 96 % ) questionnaires were successfully collected. Table No. 1 presents the demographic information of 240 participants. Who had filled in the questionnaires to happen if this factor may act upon the parents ‘ cognition about medical specialties and this factor can be utilized as evidence-based information in the hereafter. There were 104 male and 136 female respondents take parting in the study. The bulk of our respondents were 31-40 old ages old and 41-50 old ages old. Table No. 2 showed the general cognition among parents sing the OTC medical specialties. Most of parents were n't familiar with the name of medical specialties particularly in instances of diarrhoea and cough hence, the parents who would cognize and acknowledge the medical specialties for these instances were ticked â€Å" yes † and for those parents who would n't cognize and acknowledge the medical specialties were ticked â€Å" no † . Most of the parents were knowing plenty about the sorts of medical specialty that should be given to their kids during febrility, when they have cold and when they suffer from cough. To add, 194 parents know the medical specialty for concern for their kids but 46 parents do non hold that cognition. It is besides a newly-found fact that the medical specialty for diarrhoea is merely known by 41.6 % of parents, the lowest per centum gathered in the list. Parents ‘ beliefs about the signifier of medical specialty that works better for their kids. Table No. 3 showed the Parents ‘ cognition about over the counter medical specialties medical specialties to their kids. Besides, the age of parents, all inquiries was about medical specialties in general which are normally used to handle the minor complaints at place. There was a big per centum of respondents who hold the rule that medical specialty is of import for their kids. In add-on, 31 % of parents think that medical specialty can non make injury for their kids. The older parents and those with higher instruction degree and high monthly income were more knowing. Sing the side effects of medical specialties, merely 40.8 % parents know about the side effects of their kids ‘s medical specialties. Table No. 4 shows that 59.2 % of respondents agreed that the fiscal position may impact the determination of seeking medical aid for their kids. Furthermore, parents with the high instruction degree and the monthly income showed statistically important ( p=0.004 ) and ( p=0.001 ) . In add-on, 106 of respondents agreed to give addendums such as multi vitamin to their kids. Table No. 5 nowadayss that most of respondents were with moderate cognition degree and moderate direction degree. There was important association between the cognition degrees and besides the degrees of directionDiscussionThis survey has highlighted the parents ‘ medical cognition on unwellnesss of their kids every bit good as their methods of pull offing their kids ‘s complaints. A quantitative attack was used to bring forth statistically representative consequences. In our survey, showed there was no difference between the gender and their cognition about medical specialties. Most of the respondents ag ree that medical specialty is of import for their kids. They know which medical specialties should be given to their kids when they are holding febrility, cough, grippe or concern. This is likely due to the fact that these are truly the sorts of complaints which parents frequently encounter. For diarrhoea, however, merely 41.6 % of parents are cognizant of its medical specialty. This is because diarrhoea is non common among kids as the parents may be given to be excessively sensitive of their kids ‘s hygiene6. Most of the parents believe that injection and sirup work better for kids. This is because medical specialties in the injection signifier works faster than others as it straight inserts medical specialty into the blood stream. For medical specialty in syrup signifier, it works better for kids because of parents consideration that sirup can be easy swallowed by children7, and this automatically sheds visible radiation on the fact that medical specialty in Tablets or capsu les is harder to swallow.8,9 Although most of the parents think that medical specialty can be harmful, non all of them were cognizant of possible side effects of their kids ‘s medical specialty. This is because parents tend to confront troubles in obtaining information about medical specialty taken by their kids. Parents besides referred they used medical specialties information cusps as a beginning of information.10 There was a strong desire to portion duty for appraisal of their ill kid with a professional, but parents are frequently disquieted or tend to experience guilty that they might be trouble oneselfing the physician unnecessarily. Parents choose non prescribed medical specialties or ( OTC ) medical specialty to handle their kids. This is likely because they can merely give ( OTC ) because of parents consideration that sirup can be easy swallowed by kids and this automatically sheds visible radiation on the fact that medical specialty in Tablets or capsules is harder to swallow.8,9 medical special ty to their kids. Despite the deficiency of grounds for the effectivity of many ( OTC ) medications11-13 and the possible hazards associated with their improper usage among immature children,14,15 they remain widely used.16 Based on our survey, there was a important difference between the cognition degrees and besides the degree of the parents ‘ direction when be givening to their sick kids. Parents with higher cognition of kids ‘s complaints have better direction, or ‘solutions ‘ to the complaints. Their cognition and information of the kids ‘s complaints may be obtained from physicians, paediatricss, druggists, friends, books, magazines, newspaper or the internet.17 The information sought by parents may decrease the ignorance and feelings of powerlessness from the parents ‘ experience, heighten their sense of control, and modify their perceptual experiences of menace posed by an unwellness. Parents normally seek more than simple advice about pull offing the common symptoms. Information should be developed harmonizing to parents ‘ perceived demands and incorporate parents ‘ accomplishments and experiences.18 Since the degree of parents ‘ cognition influences the wellness attention picks and determinations made for their kids, utile information of kids unwellnesss should be given to parents by general practicians or wellness attention professionals. Education and advice must besides be recognized and parents ‘ normally held beliefs about viruses, self restricting unwellness, and antibiotics and their cardinal concerns about febrility, cough, and other unwellnesss should besides be addressed. Professionals could make more to authorise parents and it seems to be a good instance for aiming parents who have peculiar troubles in pull offing ill children.19DecisionThis survey shows that parents frequently have unequal cognition and misconception for hand ling their kids. From this survey, we found that parents with better and higher medical cognition have better agencies of pull offing their kids ‘s complaints when they deal with OTC medical specialties. The consequences of this survey have successfully rejected the statement that there is no correlativity between parents ‘ degree of medical cognition and the direction of kids ‘s complaints. However, by comparing the agencies of informations collected, the male parents have somewhat better medical cognition than the female parents but the female parents have somewhat better direction in their kids ‘s complaint as compared to the male parents. This survey has merely been placed in the larger social-cultural context as an illustration of the possible influence of it on wellness behaviour and the medical specialty usage. It is hoped that by placing weak countries in parents ‘knowledge, better planned educational and behavioural alteration attempts can be m ade to promote the cognition degree among the parents when it comes to pull offing or managing the complaints. One means would be the parental educational intercessions, which guarantee that kids will have the best quality of attention.

Echinoderm Facts and Information

Echinoderms, or members of the phylum Echinodermata, are some of the most easily-recognized marine invertebrates. This phylum includes sea stars (starfish), sand dollars, and urchins, and they are identified by their radial body structure, often featuring five arms.  You can often see echinoderm species in a tidal pool or in the touch tank at your local aquarium. Most echinoderms are small, with an adult size of about 4 inches, but some can grow to as much as 6.5 feet in length. Different species may be found in a variety of bright colors, including purples, reds, and yellows.   Classes of Echinoderms The phylum Echinodermata contains five classes of marine life:  Asteroidea  (sea stars),  Ophiuroidea  (brittle stars and basket stars), Echinoidea (sea urchins and sand dollars), Holothuroidea (sea cucumbers), and Crinoidea (sea lilies and feather stars). They are a diverse group of organisms, containing about 7,000 species. The phylum is regarded as one of the oldest of all animal groups, thought to have appeared at the start of the Cambrian era, about 500 million years ago.   Etymology The word echinoderm means  comes from the Greek word ekhinos, meaning hedgehog or sea urchin, and the word  derma, meaning skin. Thus, they are spiny-skinned animals. The spines on some echinoderms are more obvious than others. They are very pronounced in  sea urchins, for example. If you run your finger over a sea star, youll likely feel small spines. The spines on sand dollars, on the other hand, are less pronounced.   Basic Body Plan Echinoderms have a unique body design. Many echinoderms exhibit  radial symmetry, which means that their components are arranged around a central axis in a symmetrical manner. This means that an echinoderm has no obvious left and right half, only a top side, and a bottom side. Many echinoderms exhibit pentaradial symmetry—a type of radial symmetry in which the body can be divided into five equally-sized slices organized around a central disk. Although echinoderms can be very diverse, they all have some similarities. These similarities can be found in their circulatory and reproductive systems. Water Vascular System Instead of blood, echinoderms have a water vascular system, which is used for movement and predation. The echinoderm pumps sea water into its body through a sieve plate or madreporite, and this water fills the echinoderms tube feet. The echinoderm moves about the sea floor or across rocks or reefs by filling its tube feet with water to extend them  and then using muscles within the tube feet to retract them. The tube feet also allows echinoderms to hold on to rocks and other substrates and to grip prey by suction. Sea stars have very strong suction in their tube feet that even allows them to pry open the two shells of a bivalve. Echinoderm Reproduction Most echinoderms reproduce sexually, although males and females are virtually indistinguishable from one another when viewed externally. During sexual reproduction, echinoderms release eggs or sperm into the water, which are fertilized in the water column by the male. The fertilized eggs hatch into free-swimming larvae that eventually settle to the ocean bottom. Echinoderms can also reproduce asexually by regenerating body parts, such as arms and spines. Sea stars are well-known for their ability to regenerate arms that are lost. In fact, even if the sea star has only a small part of its central disk left, it can grow an entirely new sea star.   Feeding Behavior Many echinoderms are omnivorous, feeding on a variety of living and dead plant and marine life. They serve an important function in digesting dead plant material on the ocean floor and thereby keeping waters clean. Plentiful echinoderm populations are essential to healthy coral reefs. The digestive system of echinoderms is relatively simple and primitive compared to other marine life; some species ingest and expel waste through the same orifice. Some species simply ingest sediments and filter out the organic material, while other species are capable of catching prey, usually plankton and small fish, with their arms.   Impact on Humans While not an important source of food for humans, some forms of sea urchin are regarded as a delicacy in some parts of the world, where they are used in soups. Some echinoderms produce a toxin which is fatal to fish, but which can be used to make a medicine used to treat human cancers.   Echinoderms are generally beneficial to ocean ecology, with a few exceptions. Starfish, which prey on oysters and other mollusks, have devastated some commercial enterprises. Off the coast of California, sea urchins have caused problems for commercial seaweed farms by eating young plants before they can become established.