Brittle Stars - Ophiuroidea - The Animal Encyclopedia

Brittle stars (Ophiuroidea) are a group of echinoderms that resemble starfish. There are about 1500 species of brittle stars alive today and most species inhabit marine habitats with depths greater than 1500 feet. There are a few species of shallow water brittle stars. These species live in the sand or mud just below the low tide mark. They often live amongst coral and sponges as well. Brittle stars inhabit all the worlds oceans and live in a variety of climate regions including tropical, temperate and polar waters. Brittle stars are subdivided into two basic groups, the brittle stars (Ophiurida) and the basket stars (Euryalida). Brittle stars have a star shaped body. Like many echinoderms, they exhibit pentaradial symmetry, a 5-sided radial symetry. Brittle stars have five arms that join together at a central body disk. The arms are clearly delineated from the central body disk, and in this way brittle stars can be distinguished from starfish (starfish arms blend with the central body disk such that it is not easy to delineate where the arm ends and the central body disk begins). Brittle stars move using a water vascular system and tube feet. Their arms can move side to side but not up and down (if they are bent up or down they break, hence the name brittle star). Their arms are extremely flexible from side to side and enable them to move through the water and along substrate surfaces. When they move, they do so in a straight line, with one arm serving as the forward directing point and other arms pushing the body along that path. Brittle stars and basket stars both have long flexible arms. These arms are supported by calcium carbonate plates (also known as vertebral ossicles). The ossicles are encased in soft tissue and jointed plates that run the length of the arm. Brittle stars have a nervous system that consists of a nerve ring and that encircles their central body disk. Nerves run down each arm. Brittle stars, like all echinoderms, lack a brain. The have no eyes and their only developed senses are chemosensory (they can detect chemicals in the water) and touch. Brittle stars undergo respiration using bursae, sacks that enable gas exchange as well as excretion. These sacs are located on the bottom of the central body disk. Cilia within the sacs direct water flow so that oxygen can be absorbed from the water and waste flushed from the body. Brittle stars have a mouth that has five jaw-like structures around it. The mouth opening is also used to expel waste. An esophagus and stomach connect to the mouth opening. Brittle stars feed on organic material on the sea floor (they are primarily detritivores or scavengers although some species occasionally feed on small invertebrate prey). Basket stars feed on plankton and bacteria they catch by suspension feeding. Most species of brittle stars have separate sexes. A few species are either hermaphroditic or protandric. In many species, larvae develop inside the body of the parent. When an arm is lost, brittle stars often regenerate the lost limb. If a predator catches a brittle star by its arm, it loses the arm as a means of escape. Brittle stars diverged from other echinoderms about 500 million years ago, during the Early Ordovician. Brittle stars are most closely related to sea urchins and sea cucumbers. Details about the evolutionary relationship of brittle star to other echinoderms are not clear. Brittle stars reach sexual maturity at about 2 years of age and become full grown by 3 or 4 years of age. Their life span is generally about 5 years. Classification: Animals Invertebrates Echinoderms Brittle Stars

Dna Forensics And The Human Genome - 2744 Words

Before the 1980s, courts relied on testimony and eyewitness accounts as a main source of evidence. Notoriously unreliable, these techniques have since faded away to the stunning reliability of DNA forensics. In 1984, British geneticist Alec Jeffreys of the University of Leicester discovered an interesting new marker in the human genome. Most DNA information is the same in every human, but the junk code between genes is unique to every person. Junk DNA used for investigative purposes can be found in blood, saliva, perspiration, sexual fluid, skin tissue, bone marrow, dental pulp, and hair follicles (Phillips, 2008). By analyzing this junk code, Jeffreys found certain sequences of 10 to 100 base pairs repeated multiple times. These tandem repeats are also the same for all people, but the number of repetitions is highly variable. Before this discovery, a drop of blood at a crime scene could only reveal a person’s blood type, plus a few proteins unique to certain people. Now DNA f orensics can expose a person’s gender, race, susceptibility to diseases, and even propensity for high aggression or drug abuse (Phillips, 2008). More importantly, the certainty of DNA evidence is extremely powerful in court. Astounded at this technology’s almost perfect accuracy, the FBI changed the name of its Serology Unit to the DNA Analysis Unit in 1988 when they began accepting requests for DNA comparisons (Lewis, 1989). There are thirteen standard tandem repeats used in modern forensics, andShow MoreRelatedDna Forensics And The Human Genome2746 Words   |  11 Pages DNA Forensics Before the 1980s, courts relied on testimony and eyewitness accounts as a main source of evidence. Notoriously unreliable, these techniques have since faded away to the stunning reliability of DNA forensics. In 1984, British geneticist Alec Jeffreys of the University of Leicester discovered an interesting new marker in the human genome. Most DNA information is the same in every human, but the junk code between genes is unique to every person. Junk DNA used for investigative purposesRead MoreThe Human Genome Project1460 Words   |  6 PagesGene Essay Assignment: The Human Genome Project A genome is the complete DNA set of an organism. These DNA molecules are made up of two strands. Every strand is composed of four nucleotide bases: adenine, thymine, guanine, and cytosine. Complementary strands are paired in certain ways. Cytosine always pairs with guanine and adenine always pairs with thymine. The human genome holds about 3 billion base pairs, found in the chromosomes. 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Julius Caesar s Influence On The Roman Republic - 2031 Words

One of the most famous roman emperors was the almighty Julius Caesar. Julius Caesar had a critical and excellent impact on the Roman Empire. Although Julius Caesar’s reign on the empire was not long it was very effective. We all know Julius Caesar as an effective, powerful, and proficient ruler. In this document I will explain how Julius Caesar possess the ability to change the Roman Republic for the course of the future. I will talk about what traits of leadership Julius Caesar showed in his conquests, how the Julius Caesar fought to the dictator of Rome, and what happened to the Roman Republic and the people when he was assassinated. Let’s start at the beginning young Julius Caesar’s life. Julius Caesar, born in Rome in July 100 BC,†¦show more content†¦From that point on words Julius Caesar finally endured hardship, tension, and responsibility. His young life of lavish comfortable living have finally come to an end. Julius Caesar was born into a famil y of aristocrats, â€Å"he was an aristocrat by birth and by nature: two things that are far from synonymous† (Bradford 6). Julius Caesar had a mature mind at such an early age, â€Å"Julius Caesar want to restore to his family the glory and leadership position that his family story says his ancestors once had† (Julius Caesar). As was mostly due to the facts that his family were as well as they should have been, that his father passed away, and that Rome was under chaos. It wasn’t so Julius Caesar became a young adult, that it was sent off to Spain to fight an opposing attack on the Roman Republic. There he showed excellent leadership, remarkable courage, and an outstanding military mindset. During the battle â€Å"it is here that he shows the dynamic leadership and charisma that when markets later life† (Julius Caesar). Being able to hold his own, with his own soldiers fighting by his side, Julius Caesar also shows that he is a very good warrior as well. â€Å"And it is here as well that Caesar’s military reputation begins to build† (Julius Caesar). Julius Caesar is soon became very interested into the political world. He often thought of running for consul of the Roman Republic. I feel as if Julius Caesar had

Long Term Objectives of Apple free essay sample

Customer Related objectives †¢Launch new innovative products to keep the loyal customers intact, build new customer base and gain competitive advantage over the competitors. †¢Develop strategic approach to grow market share in emerging markets like India. In India apple I phone is still ranked after android supported phones. Internal Business Processes objectives †¢Develop ethical suppliers for its products: Unlike Foxconn (the current supplier of I phone), which usually suffers with labor unrest due to ill and unethical working conditions.In long run Apple should aim at replacing Foxconn with a better and ethical supplier because having associated with such supplier can tarnish the image of Apple and can send wrong signals to shareholders and stake holders. †¢Develop Research and Development department to identify future product innovation and development opportunities. Learning Growth (Employees) objectives †¢Reduce employee rate of attrition at middle to top management level to the industry average of 15%: Talent retention is a most important job in the fast moving technology industry where every day there is new company being fo rmed and sold for billions USD. We will write a custom essay sample on Long Term Objectives of Apple or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page The success for any company lies within the skill of human resource it has. Thus, it very important to retain the talents at middle to top level management which are involved in strategic decision making and confidential product research. †¢Employees on and above middle level management having more than five years of employment (with 4 star performance rating) at Apple computers to be willfully sent to top ranked law schools to study law and then work as patent attorney (with salary hike and other incentive) at Apple to fight against various patent issues arising (Samsung being the very latest).