Danielle Sedoris
November 11, 2009
Ecology – Friday
Parasitic Crab Lab
Background:
Mellita quinquiesperforata, commonly known as the sand dollar, is a familiar urchin on Florida coastlines. The species is flat and disk shaped that nestles into shallow sandy waters to protect itself from waves and predators. Dissodactylus mellitae is a parasitic crab that feeds on the spines of the hosting sand dollar where it remains its entire life. This study was arranged to observe the distribution patterns of crabs on various sizes of sand dollars. We hypothesized that the larger sand dollars would host more crabs because of the extended surface area available. We also predicted that the presence of adult sized crabs would limit the number of total crabs on the hosting sand dollar because of the larger size and resource demand leading to intraspecific competition among the crabs. Intraspecific competition occurs when members of the same species compete over limited resources considered vital for survival. These resources can be food, space, light, mates, anything necessary for the survival and reproduction of the individual. In our study the factors of interest are space and food.

Methods:
We began our study by surveying Ft. DeSoto’s East beach for sand dollars and their parasites. In order to avoid duplicate data collection we began 100m offshore and worked our way bacl towards the shore placing all collected samples behind us after recording the data. For each sand dollar collected, we measured its diameter and counted the number of adult and juvenile crabs present on it. Adult crabs were considered to have a width of 2mm or more and juvenile crabs were considered anything below that. We surveyed the area until approximately 100 sand dollars were collected before returning to analyze the data.

Results:
Our results showed that there is no strong correlation between the size of sand dollars and the number of crabs present. When analyzing graph 1 I noticed that...

...The SandDollar
Splash!! Of course it’s me being picked up by every human and throwing me as far away out as possible. It gets me very angry and annoyed because the humans don’t treat me with enough respect as some other organisms living here. Humans don’t look at me as a living creature and I have the same systems and some of the same body parts as them but I’m just a lot smaller in size. They get angry at me for trying to get away using my spines to move...

...Emma Diez
SandDollars
● Physical Characteristics: Sanddollars are originally a dark color, covered with
short dark spines that look almost like fur. These spines are movable, and the sanddollar uses them to move around on the sea bottom and to push small pieces of food
into its mouth. The sanddollar has an extremely short spine, about two mm long. ...

...Distribution: Wholesaling and Retailing of Food Products
A large part of the food products value-chain is distribution— (1) efficiently getting the product (2) in good condition to where (3) it is convenient for the consumer to buy it (4) in a setting that is consistent with the brand’s image.
Distribution (also known as the place variable in the marketing mix, or the 4 Ps) involves getting the product from the manufacturer to the ultimate...

...of various types of equipments for whole set of sand-making production line, and provides superior technical support for customers. The whole sand-making production line consists of vibrating feeder, jaw crusher, sand-making machine, vibrating screen, belt conveyor, electric control system, etc. We designed the production line has 30 tons to 800 tons. The whole design is simple and convenient, For customers to save time, money and space.
VSI...

...A population of measurements is approximately normally distributed with mean of 25 and a variance of 9. Find the probability that a measurement selected at random will be between 19 and 31.
Solution: The values 19 and 31 must be transformed into the corresponding z values and then the area between the two z values found. Using the transformation formula from X to z (where µ = 25 and σ √9 = 3), we have
z19 = (19 – 25) / 3 = -2 and z31 = (31 - 25) / 3 = +2
From the area between z =±2 is...

...4.2 Shapes of Distributions
Learning Goal: To be able to
describe the general shape of a
distribution in terms of its number
of modes, skewness, and
variation.
Number of Modes
One way to describe the shape of a
distribution is by its number of peaks, or
modes.
Uniform distribution—has no mode because
all data values have the same frequency.
Any peak is considered a mode, even if all
peaks do not have the same...

...The Poisson distribution is a discrete distribution. It is often used as a model for the number of events (such as the number of telephone calls at a business, number of customers in waiting lines, number of defects in a given surface area, airplane arrivals, or the number of accidents at an intersection) in a specific time period. It is also useful in ecological studies, e.g., to model the number of prairie dogs found in a square mile of prairie. The major...

...
Normal Distribution
Normal distribution is a statistics, which have been widely applied of all mathematical concepts, among large number of statisticians. Abraham de Moivre, an 18th century statistician and consultant to gamblers, noticed that as the number of events (N) increased, the distribution approached, forming a very smooth curve.
He insisted that a new discovery of a mathematical expression for this...

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