Zebra-fish Behavior - Research Paper Example

Zebrafish Behavior The zebrafish belongs to the minnow family and is popularly kept as an aquarium fish according to Hill, Teraoka, Heideman and Peterson (21). The fish is scientifically known as Danio rerio and is of the Cypriniformes order. The fish is a Cyprinidae and is related to Danio kyathit. The zebrafish is commonly found in tropical areas in fresh water environments and is useful for scientists as a vertebrate model organism. The fish is native to rivers found in the south east part of the Himalayan region and is omnivorous in nature. It mainly feeds on phytoplankton, insects, zooplanktons and insect larvae. The zebrafish may also feed on other foods including small crustaceans and wars in the event that their preferred sources are unavailable. The fish commonly inhabits ponds, streams, ditches, canals and water bodies that move slowly such as rice fields. In captivity, most zebrafish will eat tubifex worms and food flakes. Description The zebrafish is unique in that it has five uniform stripes that appear on each side of its body. The strips are uniform, horizontal and blue in color with some pigments, and extend all the way to the tip of the caudal fin (Parichy 203). Zebrafish are fusiform shaped and their mouths are usually directed upwards. Their bodies on the other hand are laterally compressed. The males may be distinguished from their female counterparts in that they are torpedo-shaped. The males also have between their blue stripes gold stripes. Females on the other hand have silver stripes and their bellies are whitish and larger than those of the males. The adult female will show a tiny genital papilla close to the anal fin – somewhere in front of where the fin originates. While a zebrafish can grow to 2.5 inches, it is not common for them to grow beyond four centimeters while in an unnatural environment. In their natural environments, the fishes may live for up to five years while they take two to three years in captivity. In many cases, the fish thrive as shoals with each shoal consisting of at least six individuals. The fish interacts well with other types of fish and are prey to many other species. In some cases, the hatchings may fall prey to larger zebrafish – more so when they live together inn an aquarium. The zebrafish is known to exhibit amazing speed which means that its nervous system is well developed in the larval stage (Travis 360). This kind of speed helps it to escape from predators such as dragon flies which often attack fast. Reproductive Behavior The zebrafish has a generation time of about three to four months. For ovulation and spawning to happen in females, a male individual must be present. The female fish will lay hundreds of eggs in water in every clutch with spawning occurring in intervals of two to three days. The eggs are usually laid at dawn or at the first appearance of light. Once the eggs have been released by the females, they start developing and are fertilized becoming transparent in nature. The fertilized embryos develop fast and within 36 hours the precursors to the main organs of the body appear. The fertilized eggs are hatched between 48 and 72 hours after fertilization takes place depending on the internal conditions of the embryos and the temperature of the environment in which they are; the ideal temperature for the growth of the embryos is 28.50C. After about 72 hours from the time of fertilization, the young zebrafish may be able to feed and swim. Zebrafish Subspecies A number of transgenic zebrafish have come into being most of which are used for commercial purposes. Some common subspecies include leopard, longfin, golden and sandy. Other subspecies express yellow fluorescent protein, red fluorescent protein, and. green fluorescent protein and are commonly called GloFish. Regeneration The zebrafish has is capable of regenerating its brain, skin, heart and fins according to Hill et al (17). However, the regeneration of heart muscles is not based on stem cells according to Stemple and Driever, Zebrafish (861). Mature heart muscle cells, instead, undergo regression to a state that resembles stem cells before undergoing dedifferentiation (Hill et al. 17; Major and Poss 222). They are also able to regenerate retinal neurons and photoreceptors when they get injured. Useful Characteristics of the Zebrafish There are quite a number of features that make the zebrafish very useful to researchers in various fields. Some of the advantages of fish that make it a preference for research model systems as highlighted by the University of Oregon and Vascotto, Beckham, and Kelly (480) are: 1 They have genetic codes that are fully sequenced; 2 They are easy to observe, understand and are testable in terms of their development behaviors. 3 It is easy to find well characterized mutants in populations of zebrafish; and 4 Their embryos are robust and sizeable and develop outside the bodies of their mothers. This means that the scientists can study under a microscope how the embryo grows into fish. These are but a few of the characteristics that make the fish valuable to scientists. In particular, the fish is important when it comes to studying the genetics and development of vertebrates. Conclusion The zebrafish generally is a fresh water fish that lives mostly in slow moving waters feeding on phytoplankton, zooplanktons and other kinds of food found in water. The female fish ovulates and lays eggs in the company of a male fish. The eggs develop fast and start feeding and swimming about 72 hours after fertilization takes place. There are quite a few sub-species of zebrafish most of which are for commercial purposes used. The zebrafish has quite a number of unique physical and biological characteristics which make it be well preferred to other animals for scientific studies. The lifetimes of the zebrafish are significantly reduced when they are taken out of their natural habitats and kept in aquarium or other unnatural environments. Works Cited Hill A, Teraoka H, Heideman W & Peterson R. "Zebrafish as a Model Vertebrate for Investigating Chemical Toxicity". Toxicological Sciences 86 (1): 6–19. 2005. Major R and Poss K "Zebrafish heart regeneration as a model for cardiac tissue repair". Drug Discov Today Dis Models 4 (4): 219–225. 2007. Parichy, DM "Evolution of danio pigment pattern development". Heredity 97 (3): 200–210. 2006. Stemple D. and Driever W. “Zebrafish: Tools for investigating cellular differentiation”. Curr Opin Cell Biol 8(6):858-864. 1996. Travis J. Gone Fishing! “Scientists use mutant zebrafish to learn how vertebrate embryos develop” Sci News 150:360-361. 1996. University of Oregon (nd) Zebrafish, Viewed 2nd June, 2010 http://www.neuro.uoregon.edu/k12/FAQs.html#Originate Vascotto S., Beckham, Y., and Kelly, G. “The zebrafishs swim to fame as an experimental model in biology”. Biochem. Cell Biol. 75:479-485. 1997. Read More