There is no doubt that arthropods are an extremely successful group of animals, with an estimated 5-10 million species worldwide[1], and this can be attributed to having an exoskeleton; it provides many benefits, such as protection from parasitism and other threats. However, one major disadvantage of having an exoskeleton is the limitations that an inelastic cuticle can place on growth. The exoskeleton provides protection, but when freshly moulted the animal is soft and vulnerable, as well as having limited mobility and use of appendages; many seek shelter before moulting[2]. There are similarities and differences between the moult cycles of all the arthropods, however only crustaceans and insects will be discussed here. The crustacean moult cycle is initiated when the Y-organ in the head secretes the hormone Ecdysone (E) into the circulatory system[3,4,5]; the Y-organ is the primary source of E[5]. Upon contact with the haemolymph (a combination of blood and tissue fluid) within the circulatory system E is converted to its active form, 20-hydroxyecdysone (20E), by a P450 enzyme[4]. This causes the epidermal cells to secrete moulting fluid, which contains a mixture of enzymes such as proteases and chitinases. The moulting fluid degrades the exo- and endocuticle, and the digested cuticle is reabsorbed to create new cuticle; moult fluid also has a role in initiating the moult. The degraded cuticle is replaced by water or air so that the animal can swell in order to lose the shell. During the passive phase of the moult cycle, the shell splits along the break point caused by the decalcification of the shell, in the crab this is along the epimeral lines. Once the shell has split, the animal wiggles side-to-side to free itself from i... ... middle of paper ... ...stem: roles of eclosion hormone and ecdysis triggering hormone. Journal of Experimental Biology, Vol. 200, pp. 869-881 19. Kuballa A. & Elizur, A. 2007. Novel molecular approach to study moulting in crustaceans. Fisheries Research Agency Bulletin, Vol. 20, pp. 53-57 20. Vafopoulou, X. & Steel, C. G. 1996. Circadian regulation of a daily rhythm of release of prothoracicotropic hormone from the brain retrocerebral complex of Rhodnius prolixus (hemiptera) during larval-adult development. General and Comparative Endocrinology, Vol. 102, pp. 123-129 21. Steel, C. G. & Vafopoulou, X. 2006. Circadian orchestration of developmental hormones in the insect, Rhodnius prolixus. Comparative Biochemistry and Physiology – Part A: Molecular & Integrative Physiology, Vol. 144, pp. 351-364 22. Feyereisen, R. 1999. Insect P450 enzymes. Annual Review of Entomology, Vol. 44, pp. 507-533
The North American brine shrimp goes through several stages in development before reaching adulthood. The brine shrimp is first encased in a protective capsule within a female brine shrimp’s brood sac (Drewes, C, 2006). Here, egg development rapidly...
Crustaceans belong to the Arthropoda Phylum, which includes critters like ants, spiders, and centipedes. I know! Crazy to think that a delicious crab is in the same group as a spider! But they share similar characteristics. For starters, members of the Arthropoda Phylum do not have a backbone like you and me, so they are called __invertebrates__. And, as mentioned earlier, their skeleton is external, which is referred to as an __exoskeleton__.
The Drosophila live a distinct four-staged life cycle that requires approximately two weeks to reach complete maturity2. The stages are known as egg, larval, pupa, and adult. The egg is a small oval shape, and can barely be seen by the unaided eye, they are hatched the day after being laid. In order for the larva to molt and grow in size it consists of three stages: first instar, second instar, and third instar3; during this process the larvae is preparing itself for metamorphosis by shedding body parts and consuming excessive nutrients. Through metamorphosis the immature fruit fly attaches itself to an object and its outer shell hardens, it then begins the transformation process into an adult. Once the process is completed, the adult is then able to begin the sexual reproduction process within forty-eight hours....
Two studies have shown that the resting metabolic rate of 11 species of cockroaches were VO2=0.261 Moles (Coelho and Moore, 1989) and 3 species of crickets were VO2=0.277 (Prestwich and Walker, 1981) are very similar.
To begin with, the horseshoe crab, one the world’s oldest living creatures, are quite active. This fascinating crab has ten small walking legs under a strong, sturdy exoskeleton, a long spine in the abdomen, and a long pointy tail in the back used to push itself back up after being flipped on its back (Swinton, 99). Furthermore, horseshoe crabs got their name in an interesting way. The crab’s arc shaped exoskeleton, or shell, was compared to a horse’s shoe (Horseshoe Crab: Saint Louis Zoo). As mentioned before horseshoe crabs aren’t actually crabs. Though it may look like one, they are actually part of a family called Limuli. Some reasons it could have been misconceived as a crab are because its shell is comparable to a crab’s, the legs look a bit similar, and they are found on the Atlantic coast like other crabs. Also we can find horseshoe crab right here in North America along the hot, sandy Atlantic
The platypus is covered with a thick water-resistant fur, excluding its bill and feet. It’s body it streamlined, has short limbs and webbed forefeet to propel itself through water using an alternative kicking motion. The webs on the for...
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.
Strait, David S. "The Feeding Biomechanics and Dietary Ecology of Australopithecus Africanus." Proceedings of the National Academy of Sciences. 12 Dec. 2008. Web. 19 Nov. 2015. .
The purpose of this lab was to study the response of the genus Daphnia to chemical stimuli and to examine human responses to different stimuli. A stimulus is an incentive; it is the cause of a physical response. Stimuli can have a physical or chemical change; an example of a physical change is a change in temperature and sound. An example of chemical change would be changes in hormone levels and pH levels. Muscular activity or glandular secretions are responses that occurs when stimulus information effects the nervous and/or hormone system. Daphnia is a genus; it is a small crustacean that lives in fresh water. The body of the daphnia is visible and its internal organs are clearly seen thus it was chosen for this exercise. The
Swan, S.H., F. Liu, J.W. Overstreet, C. Brazil, and N.E. Skakkebaek. "Growth Hormones Fed to
Gregorio Samsa, un joven viajante de comercio, tenía una vida monótona y difícil porque él tenía, sobre sus hombros, toda la carga de recientes dificultades económicas a las cuales se enfrentaba su familia, por la quiebra del negocio de su padre. Un día se vio afectado por un evento sobrenatural e inexplicable: se había convertido en un insecto. Desde ese momento nada iba a ser igual.
Deilephila elpenor moths were trained to associate a sugar reward with a color, either blue or yellow by feeding from colored artificial flowers at a light intensity equivalent to late dusk.
GHRH and GHIH regulate the release of the growth hormone as GHRH releases it and GHIH inhibits it.
With the mentor Rekha Balachandran, her research project is astonishing to me due to the concentration on circadian rhythm. As my background in psychology and biology, I have acknowledged that circadian rhythm is known to play a significant role in human physiological wellness. Disruption in circadian rhythm could affect metabolism poorly with the involvement of eating disorder as well as difficulties in storing information in short-term memory; improper functioni...
One of the first reason why insects are so successful because they possess a tough exoskeleton that is covered with a waxy water repellant layer. The exoskeleton of insects also has helped them survive. An insect's external skeleton, or exoskeleton, is made of semi-rigid plates and tubes. In insects, these plates are made of a plastic like material called chitin along with a tough protein. A waterproof wax covers the plates and prevents the insect's internal tissues from drying out. Insect exoskeletons are highly effective as a body framework, but they have two drawbacks: they cannot grow once they have formed, and like a suit of armor, they become too heavy to move when they reach a certain size. Insects overcome the first problem by periodically molting their exoskeleton and growing a larger one in its place. Insects have not evolved ways to solve the problem of increasing weight, and this is one of the reasons why insects are relatively small. But compared to animals the Exoskeletons d...