Regeneration, the process of producing tissues that resemble missing parts of an organism, is a mechanism that is beneficial to some organisms. However, when it comes to deeming an organism as being the “ideal regenerative organism”, planaria live up to this name. As observed in Figure 2 and in Figure 3, planaria are non-parasitic flatworms that reside in freshwater environments. Planarians possess the capability to compensate for missing tissues that have either been cut or decapitated, which makes them ideal models for experiments conducted by scientists (Rink et al., 2012). Regeneration in planaria typically begins once the planaria has been cut or decapitated (Pearson et al., 2009). The rationale behind the planarians’ regenerative mechanism are Neoblasts and morphogens. Neoblasts, or stem cells, are cells within planaria that are capable of becoming specialized for a certain function, because of a substance known as a morphogen. Morphogens are secreted cues, from a localized source, that induces Neoblasts to carry out a specific function within the planaria via the aid of transc...
Fox, R. 2001. Invertebrate Anatomy OnLine: Artemia Franciscana. Lander University. http://webs.lander.edu/rsfox/invertebrates/artemia.html, retrieved February 13, 2011.
Planarians are free-living, carnivorous flatworms found in the Phylum Platyhelminthes, Class Turbellaria. Although the Phylum Platyhelminthes is known for having the animals with the most parasitic species, the class Turbellaria which consist of the Planaria, are a non-parasitic species. Platyhelminthes which translates to "flat worm" are triploblastic animals. This means that they have three tissue layers, the endoderm, mesoderm, and ectoderm. Planaria also are monoecious organisms, meaning that they have both female and male sex organs in one organism. Another characteristic of the Planaria is that they do not have a true body cavity, meaning that they are acoelomate organisms.
Sabellaria cementarium belongs to the phylum Annelids and is an invertebrate polychaete species. They are found in small clumps at the rocky bottoms of the sea floor where they use the rich source of natural phytoplankton as their primary diet (Qian and Chia, 1990). The tube-like worms can behave social and form extensive reefs or independently build hollow tubes in to the sandstone (pawlik and Chia, 1991). Embryos form a polar lobe that is absorbed in to the blastomeres at the end of division. Larval development and movement follows shortly after the 14-15 hour fertilization period where spiral cleaving of the fertilized oocytes appears (Render, 1983). Much is still not known about the invertebrate worm in their natural niche.
The focus of this lab on planaria regeneration and development. Having been taught the gradient of morphogen and there were many experiments testing this possible phenomenon of regrowth. In a planarian there is a single adult stem cell type called the neoblast. Neoblast are abundantly present throughout the body and it divides continuously. This neoblast has the ability to regenerate different cell and organ types in the planarian, from the brain, digestive system, the sensory system to even the reproductive system. With this continuous stream of continuous division of cells it allows the cells of the planarian to be rapid in self-renewal of the entire
One organism well suited for regeneration is Dugesia dorotocephala, more commonly known as black planaria. Planarians are flatworms classified under the phylum Platyhelminthes and are bilaterally symmetrical. They are usually found in freshwater streams and ponds (Br, 1955). Planarians are unique in which they can reproduce both asexually and sexually. Planarians can reproduce asexually through transverse fission. Planarians are also hermaphrodites in which they can reproduce through cross fertilization. Planarians prefer to reproduce through fission where the organism splits in two and regenerates itself (Curtis & Schulze, 1933).
Planaria are one of many free-living flat worms that can be found in marine, aquatic, and terrestrial environments. Certain characteristics of planaria worms include an acoelomate body, a gut with no anus, lack of a blood vascular system, and a simple nervous system. The main reason as to why planaria are subjected to many studies is because of their unique ability to regenerate. Regeneration is the ability to re-grow lost body parts that may have been cut off. This is possible because the organism has the ability to form a blastema, which is an accumulation of undifferentiated cells, at the site of the wound. Regeneration is capable of occurring at various degrees throughout the animal kingdom. This unique process would never be able to be seen in human beings. Humans and other mammals
Some other characteristics that make worms of the phylum Platyhelminthes unique are the fact that they are light sensitive. They often try to avoid brightly lit areas. They are so sensitive because they possess’ bundles of light-sensitive eyes that are often described as primitive eyes (Snyderman and Wiseman 84). Another interesting characteristic of the flatworms is that they are hermaphroditic. This means that they posses both male and female reproductive organs. When one learns of this they may think that self-fertilization would be common, but it is not. Flatworms also posses amazing regenerative properties. When they lose a body part, a new one will form, and it some cases, the body part often regenerates an entirely new flatworm (Snyderman and Wiseman 84).
Planarians are free living flatworms that are members of the class Turbellaria and phylum Platyhelminthes. Most are seen in fresh water environments, while others are found in large mosses, on land, and even in salt water. They are soft bodied, leaf-shaped, and ciliated animals that have two eyes, and a pointed tail. They have a mouth on the ventral side of their body often located half way to their tail. They typically grow between three and fifteen millimeters in length, and are a gray, brown, or black color. Planarians move by swimming, and some are relatively fast. Majority of planarians are carnivorous and feed on things like protozoans, small snails, and worms. All planarians are hermaphrodites, meaning that they contain
In both the Enlightenment and French Revolution there were many great ideas. In the Enlightenment there was Locke’s, Voltaire’s, and Montesquieu’s ideas. They were all great ideas about freedom, religion, and the 3 branches of government. Then in the French Revolution there was the Tennis Court Oath that had lots of great ideas also. But out of all of them Locke had the best ideas.
Coral reefs are systems of large, underwater structures that are composed of the mineralized bodies of corals. These corals are a class of marine invertebrates known as Anthozoans, and belong to the phylum Cnidaria, and are thus related to sea anemone and jellyfish. Each individual coral animal is only a few millimeters in diameter, and a few centimeters in length. Due to their sessile nature, and their ability to reproduce asexually, they are able to construct, over many generations, massive colonies of genetically identical individuals. Additionally, they secrete a hard exoskeleton of calcium carbonate to support and protect their bodies, and it is from this process that the colony constructs what is known as a single coral “head.”
Caesar is dead, Brutus’ army is marching to certain death, and Antony is ready take over all of Rome with an iron fist. Around 2 months ago, normally completely unacceptable idea was about to become a reality. Cassius convinces Brutus that Julius Caesar, his best friend, needs to be killed for the better of Rome. One decision, strewn by ego and arrogance, led to the total destruction of Rome and the death of so many people. Although, there were many signs that predicted this calamity, but to none was any attention given because of the receiver’s arrogance. Despite many seemingly unmistakable forewarnings of impending disaster, the inconceivable arrogance, displayed by key conspirators, Julius Caesar, and his supporters, hindered their ability to perceive and respond to those signs in Julius Caesar.
The battle between sexual and asexual reproduction is a competition that has been ongoing for millions of years. Somewhere along the way due to its higher level of genetic variation, sexual reproduction was able to overcome the two fold advantage of asexual reproduction, and now dominates reproduction in organisms. However, some types of organisms such as worms and corals have acquired the ability to reproduce both sexually and asexually. The purpose of this paper is to explore the differences in asexual and sexual reproduction both from a biological and an evolutionary standpoint and to explain why evolution has made it possible for soft corals to reproduce both sexually and asexually.
Deontology is derived from the Greek word meaning duty. An action is considered morally right when it is a part of a person’s duties or requirements. As long as a person is following the duties, they are considered to be performing morally. Typically, this list of duties or rules are created by God in a deontological system. By acting with morals a person is obeying God’s list of duties. Christopher Bennet writes that, “Deontology, such as Kant’s ethics, there are certain types of act, such as rape, murder, theft and assault that are always wrong” (Bennet, 2010, p. 33). For example, if it is morally wrong to kill, killing is then always wrong, even if that means allowing a person to suffer. Kant believes that a person will come to know what is right and wrong by rational thought. Deontology is the most common moral theory that is widely practiced in the world, especially within healthcare. The negative side of a deontological system is that it doesn’t allow resolution between two contradictory moral duties. Looking at the example above, it is morally wrong to kill, but it is also a moral duty to not allow someone to suffer.
Evolutionary developmental biology (evo-devo) was instituted in the early 1980s as a distinctive field of study to characterise the new synthesis of evolution hypothesis (Müller, 2007). Evo-devo is regarded as a new rule in evolutionary biology and a complement to neo-Darwinian theories. It has formed from the combination of molecular developmental biology and evolutionary molecular genetics; their integration has helped greatly to understand both of these fields. Evo-devo as a discipline has been exploring the role of the process of individual development and the changes in evolutionary phenotype, meaning the developmental procedure by which single-celled zygotes grow to be multicellular organisms. Alterations in the developmental program frequently cause differences in adult morphology. When these alterations are helpful, they grow to be fixed in a population and can result in the evolution of new phyla. Evo-devo seeks to figure out how new groups happen by understanding how the method of development has evolved in different lineages. In other word, evo-devo explains the interaction between phenotype and genotype (Hall, 2007). Explanation of morphological novelty of evolutionary origins is one of the middle challenges in current evolutionary biology, and is intertwined with energetic discussion regarding how to connect developmental biology to standard perspectives from the theory of evolution (Laubichler, 2010). A large amount of theoretical and experiential effort is being devoted to novelties that have challenged biologists for more than one hundred years, for instance, the basis of fins in fish, the fin-to-limb change and the evolution of feathers. The biology of development promises to formulate a main contribution to these...
Regeneration is the process of renewal or restoration of a body, bodily part, or biological system after injury or as a normal process. [1]