Anthopleura Elegantissima Essay, Research Paper

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.