Writing in Biology

In the viable counts portion of this lab we used viable counts to observe the number of cells

present on Petri dishes inoculated with decreasing dilutions of E. coli. The E. coli were diluted in

sterile saline and spread at dilutions of 10-1, 10-2, 10-3, 10-4, 10-5, 10-6, 10-7, and 10-8. Dilution and

viable counts is a useful technique because it allows live cells to be counted, eliminating the

variable of dead cells contributing to a cell count. Colony forming units per ml (CFU/ml) were

calculated to determine the number of cells growing at each dilution. I expected the highest

CFU/ml would be from dilutions containing a higher concentration of cells, and the lowest from

the more dilute samples. . I expected that as the solutions increased in dilution, , the CFU/ml

would decrease due to less E. coli being transferred and inoculated onto the Petri dish.

The results of this experiment showed that E. coli grown at 37°C had the highest growth

rate (k), at 1.92 generations/hour and lowest generation time (g) at 31.4 minutes. The E. coli

grown at 27°C had a growth rate of 1.02 generations/hour and a generation time of 59.3 minutes.

At 45°C, the growth rate of E. coli was 0.9 generations/hour and the generation time was 66.6

minutes. The E. coli grown at 55°C did not grow sufficiently enough to calculate k and g values,

due to the high temperatures causing the cells to lyse.

As a first semester junior, Biology 551 was my first upper level course in my college career, prior to this course I only took mainly introductory level courses so this was one of the first challenges I had with taking this course. This class posed mainly challenges for me because it was also one of the first classes I took at UMass that was heavily based on teamwork and outside research projects. My previous two years were filled with lecture and exam style classes where I was not reliable for contributing to a group and most projects were small and individual. Animal communication improved my abilities to work with a group effectively and forced me to take a stronger hold on my education because I learned that I had to do a lot more outside class work in order to succeed in this class. This class improved my academic abilities, professional abilities, and sparked a stronger interest in the science of animal communication and the function of signals and interactions between animals within a species. It has also improved my abilities to think about how to carry out a research project in terms of thinking of a question and coming up with hypotheses and potential answers, and then a research method to effectively find an answer to the question.

The purpose of the experiment was to determine whether different variables of LED light affected spider behavior and web production. We set up six different enclosed environments: two with two different colored LEDs (red & yellow), two with the LEDs in different locations (top & bottom), and two with the LEDs turned off.  We put one cellar spider and two wooden sticks in each container, and left them in complete darkness under a cardboard box for three days. We measured the distance of the cellar spider from the LED in centimeters, and whether or not there was a web present, then analyzed this data. We observed that the LED light had no effect on web formation, as all of the spiders build their webs with one end attached to the LED bulb. However, the LED light did have an effect on spider behavior, as spiders exposed to LED light remained farther away from the bulb compared to spiders not exposed to light.

The social structure of killer whales is very distinct. When focusing on resident killer whales specifically, it is important to note that the basic social unit is called a matriline. This is a group of killer whales which are connected by maternal descent. This core group is highly stable with bonds that are extremely strong. Individuals are rarely seen apart for more than a few hours. Studies conducted have shown that individuals have not been seen to permanently leave any of these observed resident matrilines. Matrilines may consist from 1 to 4 generations of related whales. Pods are the next social structure - which consist of related matrilines that travel and hunt together. Pods are less stable and it is not unusual that a matriline will break away from the pod for an extended period of time. Beyonds pods, are clans. Clans are made up of pods with similar vocal dialects, and may be related. Pods may have developed from one ancestral pod which fragmented over time. Pods from different clans are frequently seen traveling together. The last social level is a community. Whales do not share common maternal links or vocal similarities, but simply share a geographic range.

    Similar to resident killer whales, the matriline is basic social unit in transient whales. However they are typically smaller in size, and juvenile and adult offspring can disperse for long periods of time or even permanently. Consistency in grouping patterns is not common. Associations are more dynamic in transient killer whales as well.

Temperature affects many physiological and biological processes in the body. Spiders are ectothermic organisms, so they are unable to regulate their body temperatures relative to their environment. As a result, changes in temperature can have a large impact on their metabolic rate and overall activity. Our project focuses on the effect of temperature on web production in P. phalangioides. To study this, we created three different environments with varying temperatures for spiders to live in and create webs. We had a cool environment that averaged at 11.6 degrees celsius, warm environment at 26.2 degrees celsius, and a control environment at 19.4 degrees celsius. We put three spiders, each in their own cup, in each environment and allowed them to produce webs for five days. We then compared the final weights of the webs in the different environments. It was concluded that spiders in cooler environments typically yielded lighter webs than spiders in warmer environments. 

Our project involves measuring the width of spiders, along with their weight to determine a possible relationship. We accomplished this by using an advanced microscope and individual spider silk. Silk was obtained from the spiders. The spiders were all in the same environment to ensure the variables were the same. Our results showed a negative trend in the relationship, with the heaviest spiders having the thinnest silk. This could be a potential sampling error, and increasing the sample size would offset this. 

The aim of this study was to determine if there is a relationship present between the body weight of spiders and silk thickness, as well as to determine the relationship between weight and thickness among various species of spiders (Pholcus phalangioides, Araneus diadematus, Nephila edulis, Latrodectus mactans, and Euprosthenops sp). We hypothesized that spider silk thickness would increase with the weight of a spider.

Exploring the various factors that contribute to differences in spider web characteristics, such as thickness, could help us learn more about the factors that contribute to their high elasticity and can be useful for the material engineering of a material that is both strong and soft. The diameter of the web is important because it provides some clue as to what the spider uses the web for. There is some variation in spider silk diameters, as well as the mechanical characterization of silk (Blackledge et. al. 2005).

In this study, three spiders were weighed at the beginning of the experiment and they spun webs for 3 days after being weighed to allow for the production of a sufficient amount of silk. After the third day, the thickness of an individual strand of silk from each web was measured using a microscope and micrometre. The measurements of weight and silk thickness were compared to data retrieved from another study (Shao, Z. Vollrath, F. 1999), in which the same variables were measured under similar conditions to determine if a relationship existed between weight and silk thickness.

The conclusions reached as a result of this experiment is that there is a negative relationship in the spider weight-silk diameter of Pholcus phalangioides. However, out data has a wide range of data and may not be conclusive. According to measurement results retrieved from another article for (Araneus diadematus, Nephila edulis, Latrodectus mactans, and Euprosthenops sp), these spiders do not have a clear pattern between weight and silk thickness. This suggests that there is no correlation between the weight of a spider and the thickness of the silk.

• Elevator speech: Our experiment researched whether or not a relationship existed between the weight of cellar spiders and the thickness of the web they produced. We weighed three spiders and were able to collect web from their containers. We took images of the webs using a nikon inverted microscope and then took the measurements of the thickness using a software called “Fiji”. Our data displayed a negative trend, however, other similar studies done show no relationship between the weight and thickness of spiders of different species. To improve our research and to find better data it would be beneficial to take measurements from more spiders of a wider range of weight and find a way to be more consistent in measuring the silk thickness.

This species has developed a series of adaptations for navigating underwater during short periods of time. Its nostrils and reduced ears close underwater, and due to having its eyes protected by a full nictating membrane it mostly relies on its highly sensitive long whiskers for detecting its prey or other obstacles. Nonetheless, this species has good vision on land and uses it for detecting potential prey instead of echolocation, which has been lost in favor of smaller ears that provide better streamlining.