Luidia Clathrata Case

In this research project ten sea stars (Luidia Clathrata) were collected off the Gulf of Mexico using a dredge, on February 19, 2013. They were transferred to 25 and 30 gallon tank aquariums on the campus of P.K.Yonge DRS in Gainesville, Florida. The sea stars were then separated into four individual tanks. The tanks had a salinity had a salinity average of 26 parts per thousands (ppt). One sea star, which had lost two arms, was measured every other day and growth of arms was recorded if there was any. The objective of this lab was to see how quickly the arms grew back and to record the data. Our tank was prepared with 20 pounds of live sand and aerated with an aqua clear 200 liter. A small net was used to retrieve the sea stars and a 30 centimeter ruler for measuring. Through the research it was discovered that it takes around seven month's to a year for a sea stars arm to fully regenerate. My experimental hypothesis was that the sea stars arms would grow and average of 0.5 cm a week. The hypothesis was partially upheld and rejected. The new arms 4 and 5 grew an average of 0.5 cm a week, but the others arms either grew slowly, fast, or stopped growing.

Introduction:

Sea stars (Luidia Clathrata) are echinoderms belonging to the class Asteroidea. The names "starfish" and "sea star" all refer to the members of the class Asteroidea. There are about 1,800 living species of star fish that thrive in the world's oceans, including the Atlantic, Pacific, Indian, Artic and Southern Oceans.

A sea star can regenerate its arm. It must first go through a healing process to fix the wound. (Gomez, 2009) Once the arm is healed the sea star makes new cells. The phase of re-growing the arms can take anywhere from seven months to a year. Cell Proliferation happens in the final phase of the growth. Cell Proliferation is an increase in the number of cells from cell growth or cell division. If the final phase is interrupted in any way the sea star may have deformed arms (Gomez, 2009).

Sea stars can also reproduce asexually or sexually. If they choose to reproduce asexually, they split their central disk into small pieces, this process in called fission. They can also reproduce asexually by breaking off part of their arms. Sea stars will also break off their arms to get away from predators. (Gomez, 2009). Each part of that central disk can under go with the regeneration process that results with a new sea star. It is not likely that a wounded limb will be able to regenerate into a fully grown sea star unless it is already attached to a portion of the central disk. Regeneration from a damaged limb with no central disk has been seen in some species of sea stars, including Linckia diplax. (Mladenov, 1983). It's not impossible, but it is very unlikely.

Michael C.L. Vickery, from the University of Alabama at Birmingham and his fellow colleagues, did an experiment