Реферат: Anthopleura Elegantissima Essay Research Paper Emily PorterfieldEnglish

Anthopleura Elegantissima Essay, Research Paper

Emily Porterfield

English 112

Erin Sloan

1-30-99

Anthopleura elegantissima

The sea anemones that were collected for the ?Clone Specific Segregation in the

Sea Anemone Anthopleura elegantissima? experiment were collected by Lisbeth Francis

in Pacific Grove, California (Biological Bulletin 1973, 144; 64-72). The topic of

Francis?s report is the particularity of the constant anemone-free areas dividing

contiguous accumulations of these anemones and the connection of these areas to the

dispersion and manner of these anemones. In her report Francis describes how she did

her experiment and the result of each step. Francis also includes a discussion section

where she discusses advantages versus disadvantages of segregated aggregations and

organisms that are similar to these sea anemones.

Francis first explains the materials and methods. One of the first steps in this

section is collecting the anemones. Slowly sliding a spatula under the sea anemones,

Francis dislodged them from the immense rocks to which they were attached. At the

laboratory they were kept in glass bowls containing water from the sea and were fed

periodically, exclusive of experimentation time. In case of any impairments from the

collection process, the anemones were kept in these bowls for a few weeks before any of

the experiments started. Only the most healthy anemones were used in the experiment.

To free the anemones, Francis hit the bowl against a solid surface. To determine the sex

of the anemones, they were severed and inspected for sex organs. When their sex organs

are fully grown the female?s are brownish-pink and they male?s are yellowish-white. The

anemones that contain one or more sex organs including oocytes or spermatocytes were

recorded as having developed sex organs. The anemones were then placed in a drying

oven for approximately 18 to 24 hours, so they could be dried to a constant weight.

The anemones living in clusters isolated from other clusters were inspected to

ascertain whether or not the anemones from each cluster were different. The anemones

living in the same cluster, Francis noticed, had identical color patterns. There were other

color patterns observed, but they always occurred when the cluster was separated by an

anemone-free area. In each of the aggregations observed, Francis noticed that the sex of

the anemones was the same. There were either all males living together or all females.

None of the aggregations were integrated. Francis?s conclusion from this is that since

they ?reproduce asexually by longitudinal fission? (403), each cluster is a clone and the

anemone-free areas divide contiguous clones. From studying how size is related to

sexual maturity in sea anemones, Francis drew another conclusion. She states that the

more the anemones weigh, the more likely they are to be sexually developed.

Francis?s next experiment was to try to figure out if the anemones could place

themselves into segregated groups. She collected anemones from two clones living

beside each other and attached them to a plastic ball with a lead weight inside an

aquarium. They were crammed together in five horizontal lines with four animals in

each line. The anemones were arranged so that they were all mixed together

heterogeneously instead of separated into their two separate groups. Three days later the

anemones looked as if they were fairly attached to the ball so Francis removed the pins to

let them move around so she could observe what kind of groups they formed. Thirteen

days later, four of them had fallen off the ball and the other sixteen had organized

themselves back into their segregated groups. They moved around some more after

thirteen days, but there was not any connection between the two groups. Francis

concluded from this experiment that segregation between clones can be established by

the anemones themselves.

The next experiment Francis conducted was to discover if the anemones would

create anemone-free zones in-between clonal groups if there are no other species of

animals and no waves. In this experiment the anemones were collected from two

different clones but they were not side-by-side. Francis also kept them in the laboratory

for an extended period of time (up to a year). A baking dish was lined with foam plastic

and on one side, one clone of anemones was attached with insect pins and the other clone

was attached to the other side. Microscope slides were lined up and taped together to

prevent any contact between the two clones. Sea water was running into one side of the

dish. The flow of the water was changed periodically because the anemones are inclined

to move upstream and Francis didn?t want the flow of the water to affect her experiment.

The insect pins and the microscope slides were removed. Pictures were taken once a day

to determine how much the anemones were moving each day. Within three weeks an

anemone-free zone was formed between the two clonal groups. During this time Francis

also observes some aggressive behavior. After this experiment, Francis concluded that

anemone-free zones can be formed by the anemones without the presence of other

organisms.

When contemplating why anemones might live in clusters instead of individually

Francis had three main points. Living in clusters: lessens water loss and damage from the

waves, makes it harder for other ocean life to settle and compete, and it is easier to

procure and hold large animals. Also, the patterns that Francis observed in these

anemones are not unique to this species. Some of these same patterns occur in other

species of organisms. Other scientists have observed other organisms living very close

together with no tissue fusion. Others have also observed ?complete fusion at the

interface between separate growing edges of the same colony both in the encrusting

ascidian Botrylus and in a variety of bryozoa? (407). These phenomena are

corresponding because of the ?contrast between the intimacy of association among

genetically identical ?individuals? in colonies or clonal groups, and the relative isolation

between genetically different individuals of the same species? (407).

Marine Biology is the study of the origin, history, characteristics, and habits of

plants and animals. Marine Biologists usually specialize in one taxon and study one

specific organism. Francis?s article relates to the discipline of Marine Biology because

her article focuses on the specific sea anemone Anthopleura elegantissima. In her

article, Francis commences with details in her materials and methods section. This

implies that this is a very significant section. She also incorporates charts into her

procedures and results section, which helps to prove that her research is legitimate and

helps us to understand the experiment more thoroughly. Francis incorporates the

procedures section in with the results section which is not done frequently in a biological

report. In the last section of the first part of Francis?s procedures and results section she

includes some interpretation, which seems to indicate some difficulty with organization.

She states that ?No other hypothesis can simply explain…?(403). Francis didn?t include

these interpretations in all of her sections, only in this one and in her discussion section,

where it really belongs. Also, in her fourth section she includes extra, unnecessary

material. She states, ?During this time numerous aggressive episodes were observed at

the border between the two groups?(406). She goes on to say that she did not notice this

in the preceding experiment, which was done before this one. Her inclusion of ?similar

phenomena?(407) indicates that it is important to relate other organisms to the ones

being observed. Francis?s article was very comprehensive although she seems to have

difficulty staying focused and organized.