Final Molluscs of Bahamas
This topic submitted by Mark Dalman (
pre8lude@hotmail.com) at 3:35 PM on 7/29/02.
We had a terrific group of people in our recent course in the Bahamas
July 31, 2002
Beginning around the month of November, Dr. Cummins and I, began postulating and researching a proposal based upon our trip to Grahams Harbor, San Salvador, Bahamas. At first, he and I were going to just ask for any old research grant, however, I asked him if we could submit an application for the U.S.S. (Undergraduate Summer Scholars) Award. Of course, he being the highly motivated and greatly involved individual he is, we soon collaborated on a more extensive and involved proposal to submit to the USS committee. Our proposal title was deemed: The Beat Goes On: Quantifying the Effects of Global Change on a Pristine Tropical Lagoon, Grahams Harbor, San Salvador, Bahamas. The proposal idea consisted of researching the molluskan species prior to matriculation to the Bahamian Field Station. Upon arriving at the station, Dr. Cummins, Becky Deehr, and myself are to take three transects with eight samples at each one. One is near the beach, another is approximately 1000m from the beach, and the final one is out near the barrier reef. Evaluating these three transects will help us, the scientific community, to realize and understand the differences encountered with varying depth, current strength, and sea grass density in regards to global change. In taking these cores we will have a vertical representation of the present and past community make up.
With the coming of the New Year, 2002 came a wonderful surprise. Dr. Cummins and myself received notification of the acceptance of our proposal by the USS committee. Along with the acceptance, came a fellowship and supplies grant of $3,400, 12 semester credit hours, and an in-depth and honoring mentorship lasting a minimum period of ten weeks. I mentor was none other then Dr. Hays Cummins.
Going into further detail about our research, we plan on acquiring our three transect samplings where we will statistically analyze the species abundance and sea grass density to research previously published by two of our classes members, Dr. Cummins and Becky Deehr, as well as Dr. Boardman and Rick Zimmerman. As stated in the proposal title we will continue the ÒbeatÓ by evaluating the species to the ever-changing global trend to determine if there is a correlative effect. With the culmination of our research in the Bahamas, we will take the three transect samples back to Boyd Lab in Oxford, Ohio to finish the rest of the counting and identifying of the species. Once finished with the research I will present a poster session at the USS symposium and hopefully have my research published by 2004.
The phylum of Mollusks is known since the lower Cambrian (about 500 million years ago). The phylum contains species such as gastropods (snails and shells), bivalves (mussels, clams and, oysters) and cephalopods (squids and octopus). The number of species within the mollusks is still in discussion. Previously the count was about 110,000 Ð 130, 000, the current status of knowledge is at about 50,000 species. Of these, about 48,750, which are by far the larger part, are gastropods (48,000), bivalves (8,000), and cephalopods (750).
Systematically, the name Mollusca has been founded by the French naturalist, Georges Cuvier (1769- 1832). In the systema naturae by Carl Von Linne, the mollusks were put together with different groups of non-legged animals such a worms (ÒvermsÓ). Today, we know that there are different groups of worms that primarily have nothing to do with each other except being animals.
Mollusks are unsegmented animals other e.g. then the arthropod animals (such as insects). The common composition of Mollusks comprises a musculous foot, a head and a visceral sac is covered by a skin fold called the mantle (pallium). Cells in the mantle epidermis usually produce a hard calcareous shell, which does not serve as a skeleton, having no stabilizing function, but as a protecting dorsal cover. The mollusk body does not provide any kind of skeleton, which led to the systematic name of mollusks- soft animals.
The foot is the molluskÕs main locomotry organ. It is very musculous and moveable. Movement among mollusks besides crawling can contain free swimming, digging, and other procedures. The foot is covered by a skin producing mucus or slime. Mostly the slime serves to reduce friction between the foot and the underground, among land living mollusks (snails) the slime also serves as a protection against drying and against predators.
Most mollusks have a head as the center of sensual perception. Most mollusks then possess eyes of different developmental stages from pit-shaped eyes among mussels and primitive snails up to lense eyes among more highly developed snails and cephalopods. The mollusks have cephalized their head region to produce todayÕs modern day mollusks.
The head is the location of the mollusksÕ mouth opening; they do not have teeth like vertebrates, and instead have a rasp tongue called a radula. Their excretory and digestive systems are similar to most vertebrates.
Most mollusks have originated as sea living organism. Even today most molluscan species live in the sea. Besides the snails, especially the bivalves have managed the transition from the sea to the fresh water. Together with that mostly happened a change in reproduction and development of the young.
Mollusks have been to interest to man since ancient times. Some species are edible and for that reason have partly become relatively rare. Shells and other mollusk products (pearls and purple color out of a shell), as well as, mollusks shells have been used by art and manufacture especially in countries next to the sea. The so-called shell craft means manufactures of artwork and jewelry out of mollusk shells. The aesthetic of some mollusk shells can be described by mathematical formulas, but it is also a part of artwork and paintings especially from ancient and medieval times. Seashells served as money in certain countries. Others are used as a trumpet by Japanese priests, as well as in ancient times in the Mediterranean.
The death assemblage term is something that is not know to the average individual. In our research, we plan to take a vertical core samples that illustrate the past community assemblage, both living on top and dead below. We plan on comparing the present day assemblage to ten years ago and also that of 500 years ago. With doing this, we will have a better understanding of the species abundance past and present communities as well as hopefully are able to predict those of the future. Along with the samples we plan on analyzing the sea grass abundance to determine if that affects the number of specimens and species diversity. By better understanding the influential factors that interacted with those things of the past and present we should be able to project what the future assemblage will look like in the future.
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