As early as the 18th century, the planarian flatworm of the genus Dugesia has been a great matter of interest within the scientific community largely due to their regenerative capabilities (Dasheiff 2002). Abundant, inexpensive, easy to cultivate and having a relatively short regeneration period make this planarian a stellar candidate for a host of ecological and pharmacological studies (Zhang et. al. 2012; Cebrià 2007).
D. dorotocephala belongs to the phylum Platyhelminthes, class Turbellaria, order Tricladida, and genus Dugesia. They are characteristically non-parasitic, acoelomate, bilaterally symmetric, and hermaphroditic. D. dorotocephala is a free-living flatworm that lives in freshwater streams or ponds where they are predators to smaller invertebrates (Reddien and Alvarado 2004).
These flatworms do not have a circulatory system present, rather gas exchange is achieved by diffusion through the body wall and excretion and osmoregulation are achieved by protonephridia. The body wall consists of longitudinal, diagonal, and circular muscles that are generally used in maneuvering obstacles rather than functioning in locomotion, which is reserved for their ciliated epithelium (Reddien and Alvarado 2004).
D. dorotocephala has a relatively simple brain and central nervous system: ventral longitudinal nerve cords connect to bi-lobed cephalic ganglia and basic sensory structures such as ocelli and auricles at the anterior end of the body that project to the cephalic ganglia (Reddien and Alvarado 2004).
D. dorotocephala is able to reproduce sexually or by fission, architomy or other forms of asexual reproduction. In close relation to their methods of asexual reproduction is their most notable feature: the ability to regenerate p...
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...gative behavior. This is not the case, however.
There are many ways in which this experiment could be improved. Among the replicates in the experiment, there was no consistency in the light source, intensity, duration of exposure or position of the light relative to the animal during the phototaxis experiments. This may have been the culprit of inconsistent results and observations of positive phototaxis. More precise methods of measurement are also needed. All around, greater uniformity in the methods of observation and experimentation among replicates would greatly improve the reliability of data collected. If future experiments can exert greater control of variation among replicates, the study of D. dorotocephala and its regenerative capacities can provide valuable information that has the potential to greatly benefit ecological and pharmacological research.
Ryazantseva, I. N., Saakov, V. S., Andreyeva, I. N., Ogorodnikova, T. I. and Zuev, Y. F. 2012. Response of pigmented Serratia marcescens to the illumination. Journal of Photochemistry and Photobiology B: Biology, 106 p. 18-23
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.
In reproduction, the female produces clusters of eggs that she carries in one or two egg sacs that are attached to her abdomen. Once hatched, The T. Californium’ life cycle has quite a few stages. The first being six naupliar (young) stages lasting 4 – 10 days. Next come the 6-copepodite stages (7-14 days for the first 5 stages) ending in the last stage where T.californicus is a sexually mature adult. Adults then live from 40 – 90 days after the stages are complete (Rickets and Calvin 1985).
Cephalopods are known to be exceptionally intelligent by invertebrate standards and in some respects even rival “higher” vertebrates. These animals have many highly evolved sensory and processing organs that allow them to gain a greater understanding of their environment and their place within it. Due to their advanced structures, many of which are analogous to vertebrate structures, and abilities they have been widely studied. Their methods of learning have been of prime interest and many experiments have been conducted to determine the different ways in which octopuses can learn. From these experiments four main kinds of learning have been identified in octopuses: associative learning, special learning,
2)Campbell, Neil A., and Jane B. Reece. Biology. San Francisco, CA: Benjamin Cummings, 2008. Print.
Flatworms belong to the phylum Platyhelminthes. They have the simplest body plan of all bilaterally symmetrical animals. They are called flatworms because their bodies are compressed. The mouth is the only opening into the digestive cavity the flatworms have. Food is taken in through this hole and wastes are discharged also through this hole. Flatworms have a well-defined nervous, muscular, excretory, and reproductive system. The flatworm distributes the food it digests through a digestive tube that branches throughout all of its body parts. The fact that the worm’s body is flat serves many purposes. It allows the worm to hid in small spaces, to fit into the opening of other animals if the worm is parasitic, and it means that all the cells are close enough to the surface for exchange of oxygen and carbon dioxide with the environment (Meinkoth 399).
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
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.
The next step includes the two nuclei of the dikaryon fusing through karyogomy (Ross 146). The resulting diploid zygotic nucleus then undergoes meiosis, and four haploid nuclei are formed in the basidium (Webster 280). The haploid nuclei move into projections on the basidium, which turn into spores. The spores are attached to the sterigmata until they are released (Ross 146). The cycle then starts over again.
In any production of certain metabolites or products in fungal life cycle, two phases of metabolism must involve which are primary and secondary metabolisms. In this new and modern era, fungal biotechnology has evolved and developed in order to allow a commercially fungal utilization of the metabolic processes in a viable manner. To conclude, fungi have contributed a lot in economy significantly. This included in the industries of chemical commodities, antibiotics, enzymes, vitamins, pharmaceutical compounds, fungicides, plant growth regulators, hormones and proteins.
The Venus Fly Trap, Dionaea muscipula, is a carnivorous plant native to the bogs and swamplands of North and South Carolina. It is an interesting plant and this research paper will be covering the adaptive significance in the insectivtory of the Venus Flytrap and how this evolved into an adaptation for obtaining nutrients in their nutrient poor habitat. How their prey is captured, digestion, lifespan, and vulnerabilities will also be discussed. Including what happens if something other than a bug used for nutrients triggers their traps, and what the actions that take place are when this happens. There is also a reason to believe that this species is at risk for extinction due to fire suppression and poaching.
Arachnida is a subphylum of Arthropoda, consisting of over 100 000 species, many of them being parasites which can carry disease. They are found in all environments, and mostly have eight legs, which is a feature, together with the fact that they do not have wings or antennae, often used to distinguish them from the other subphyla, though there are exceptions. They include spiders, scorpions, ticks and mites. Their bodies are divided up into three parts: the cephalothorax, the opisthosoma and the thorax, and use a type of lung for gas exchange. Most Arachnids are carnivorous, and eat pre-digested insects and other small animals. They reproduce using internal reproduction usually lay eggs, except for the scorpion which bears living young. The word ‘Arachnid’ comes from the Greek word ‘Arachne’ meaning ‘spider’.
The reproductive system was mainly located towards the anal area and inferior to the stomach. The penis was located in the middle. It was white in color and looked like a mealworm. The seminal vesicles were located on both sides of the penis. They were grayish pink in color and looked like walnuts.
J. Losos, K. Mason, S. Singer, based on the work of P. Raven, & G. Johnson, Biology, 8th ed., (McGraw-Hill Education (Asia), Singapore, 2008), pp. 994-995.
The world we live in today is full of an exceptional variety of animals. The time it took to conclude to the various sorts of species seen today has been throughout a period of millions of years. The vast majority of these animals are accredited to evolutionary advancements. When the environment changes, organisms have become accustomed to changing to fit their environment, to ensure their species does not die off. These physical changes have resulted in different phyla, ranging from basic structures, like sponges to advance systems, like that of an octopus.