Unit 12 Animal World
The Medusa and the Snail
Before you read
a. What do these pictures mean?
b. How are they different?
Now read the following text about the importance of interdependence at the present time and do the given tasks.
We’ve never been as self-conscious about ourselves as we seem to be these days. The
popular magazines are filled with advice on things to do with a self: how to find it,
identify it, nurture it, protect it, and even, for special occasions, weekends, how to lose
it transiently. There are instructive books, best sellers on self-realization, self-help,
and self-development. Groups of self-respecting people pay large fees for three day
sessions together, learning self-awareness. Self-enlightenment can be taught in college
You’d think, to read about it, that we’d only just now discovered selves. Having long
suspected that there was something alive in there, winning the place, separate from
everyone else, absolutely individual and independent, we’ve celebrated by giving it a
It is an interesting word, formed long ago in much more social ambiguity than you’d
expect. The original root was se or seu, simply the pronoun of the third person, and
most of the descendant words, except “self” itself, were constructed to allude to other,
somehow connected people; “sibs” and “gossips,” relatives and close acquaintances,
came from seu. Se was also used to indicate some side or apart, hence words like
“separate,” “secret”and “segregate.” From an extended root swedh it moved into Greek
meaning people of one’s own sort, and ethos, meaning the customs of such people.
“Ethics” means the behavior of people like one’s self, one’s own ethics.
We tend to think of ourselves as the only wholly unique in nature, but it is not so.
Uniqueness is so commonplace a property of living things that there is really nothing
at all unique about it. The phenomenon can’t be unique and universal at the same
time. Even individual, free-swimming bacteria can be viewed as unique entities
distinguishable from each other even when they are the progeny of a single clone.
Spudich and Koshland have recently reported that motile microorganisms of the same
species are like solitary eccentrics in their swimming behavior. When they are searching
for food, some tumble in one direction for precisely so many seconds before quitting,
while others tumble differently and for different, but characteristic, periods of time. If
you watch them closely, tethered by their flagellae to the surface of an antibody-coated
slide, you can tell them from each other by the way they twirl, as accurately as though
they had different names.
Beans carry self-labels, and are marked by these as distinctly as a mouse by his special
smell. The labels are glycoproteins, the lectins, and may have something to do with
negotiating the intimate and essential attachment between the bean and the nitrogenfixing
bacteria which live as part of the plant’s flesh, embedded in root nodules. The
lectin from one line of legume has a special affinity for the surfaces of the particular
bacteria which colonize that line, but not for bacteria from other types of bean. The
system seems designed for the maintenance of exclusive partnerships. Nature is pieced
together by little snobberies like this.
Coral polyps are biologically self-conscious. If you place polyp of the same genetic
line together, touching each other, they will fuse and become a single polyp, but if the
lines are different, one will reject the other.
Fish can tell each other apart as individuals, by the smell of self. So can mice, and
here the olfactory discrimination is governed by the same H2 locus which contains the
genes for immunologic self-marking.
The only living units that seem to have no sense of privacy at all are the nucleated
cells that have been detached from the parent organism and isolated in a laboratory
dish. Given the opportunity, under the right conditions, two cells from wildly different
sources, a yeast cell, say, say, and a chicken erythrocyte, will touch, fuse, and the two
nuclei will then fuse as well, and the new hybrid cell will now divide into monstrous
progeny. Naked cells, lacking self-respect, do not seem to have any sense of self.
The markers of self, and the sensing mechanisms responsible for detecting such
markers, are conventionally regarded as mechanisms for maintaining individuality for
its own sake, enabling one kind of creature to defend and protect itself against all the
rest. Selfness, seen thus, is for self-preservation.
In real life, though, it doesn’t seem to work this way. The self-marking of invertebrate
animals in the sea, who must have perfected the business long before evolution got around to us, was set up in order to permit creatures of one kind to locate others, not
for predation but to set up symbiotic households. The anemones who live on the shells
of crabs are precisely finicky; so are the crabs. Only a single species of anemone will
find its way to only a single species of crab. They sense each other exquisitely, and live
together as though made for each other.
Sometimes there is such a mix-up about selfness that two creatures, each attracted
by the molecular configuration of the other, incorporate the two selves to make
a single organism. The best story I’ve ever heard about this is the tale told of
the nudibranch and medusa living in the Bay of Naples. When first observed,
the nudibranch, a common sea slug, was found to have a tiny vestigial parasite,
in the form of a jellyfish, permanently affixed to the ventral surface near the
mouth. In curiosity to learn how the medusa got there, some marine biologists
began searching the local waters for earlier developmental forms, and discovered
something amazing. The attached parasite, although apparently so specialized as
to have given up living for itself, can still produce offspring, for they are found in
abundance at certain seasons of the year. They drift through the upper waters, grow
up nicely and astonishingly, and finally become full-grown, handsome, normal
jellyfish. Meanwhile, the snail produces snail larvae, and these too begin to grow
normally, but not for long. While still extremely small, they become entrapped in
the tentacles of the medusa and then engulfed within the umbrella-shaped body.
At first glance, you’d believe the medusae are now the predators, paying back for
earlier humiliations, and the snails the prey. But no. Soon the snails, undigested
and insatiable, begin to eat, browsing away first at the radial canals, then the
borders of the rim, finally the tentacles, until the jellyfish becomes reduced in
substance by being eaten while the snail grows correspondingly in size. At the end,
the arrangement is back to the first scene, with a full-grown nudibranch basking,
and nothing left of the jellyfish except the round, successfully edited parasite,
safely affixed to the skin near the mouth.
It is a confusing tale to sort out, and even more confusing to think about. Both creatures are
designed for this encounter, marked as selves so that they can find each other in the waters
of the Bay of Naples. The collaboration, if you want to call it that, is entirely specific; it is
only this species of medusa and only this kind of nude branch that can come together and
live this way. And, more surprising, they cannot live in any other way; they depend for their
survival on each other. They are not really selves, they are specific others.
What does the collaboration of the selves tell us about our identity?
The thought of these creatures gives me an odd feeling. They do not remind me of
anything, really. I’ve never heard of such a cycle before. They are bizarre, that’s it,
unique. And at the same time, like a vaguely remembered dream, they remind me of
the whole earth at once. I cannot get my mind to stay still and think it through.
– Lewis Thomas
Working with words
A. Read the text and tick the best alternative to fill in the gaps.
a. Persons who are related to you and who live after you, such as your child or grandchild are called ……..
i. relatives ii. descendants iii. siblings
b. ‘……………’ means to turn or spin around and around quickly
i. Twirl ii. Fold iii. Fetter
c. ……….. are proteins which contain oligosaccharide chains (glycans) attached to amino acid side-chains
i. Glycoproteins ii. Legumes iii. Meat products
d. ………. are carbohydrate-binding proteins that are highly specific for sugar groups that are part of other molecules and so cause agglutination of particular cells.
i. Lactose ii. Legumes iii. Lectins
e. ….are abnormal tissue growths that most often look like small, flat bumps or tiny mushroom like stalks found in the phylum Cnidaria and the medusa
i. Polyps ii. Buds iii. Tulips
f. …………. is a biological interaction where one organism, the predator, kills and eats another organism, its prey.
i. Murder ii. Homicide iii. Predation
g. ………. is a genus of flowering plants in the buttercup family.
i. Anemone ii. Ammonia iii. Amoeba
h. A/An …………… person is extremely or excessively particular, exacting, or meticulous in taste or standards.
i. arrogant ii. finicky iii. symbiotic
i. …………. is a group of soft-bodied, marine gastropod molluscs which shed their shells after their larval stage.
i. Shell ii. Nudibranch iii. Jellyfish
j. A …….is a free-swimming sexual form of a coelenterate such as a jellyfish, typically having an umbrella-shaped body with stinging tentacles around the edge.
i. medusa ii. sea horse iii. sea slug
B. Look up a dictionary and write the meanings of the following words then use them in your own sentences.
arthropod, gastropod, biomass, calcification, metamorphosis, sturgeon
Answer the following questions.
a. What are the indicators of the fact that we are very self-conscious about ourselves these days?
b. How have we celebrated the fact that we have our individual identity?
c. Are we, human beings, really unique? Why/Why not?
d. How do fish recognize each other?
e. What is the function of individuality?
f. What does the mix-up of two selves tell us about our identity?
g. What does the author illustrate with the tale of the nudibranch and the medusa?
h. Why is the author disturbed by the thought of the creatures like the nudibranch and medusa?
i. What does the writer mean by “they remind me of the whole earth at once?”
a. How does the author make satire on the modern idea of the ‘self’ based on individuality, independence and uniqueness?
b. Analyze the essay as a creative defense of the interdependence observed in the ecosystem.
A. Write an essay on “Independence vs. Interdependence” in about 250 words.
B. Write a newspaper article highlighting the increasing individualism in the modern Nepali society.
A. Make passive sentences from the following information as in the example.
Toyota cars/Japan/make : Toyota cars are made in Japan.
b. spaghetti/boiling water/cook
c. each lesson/an exercise/follow
d. taxes/the price/include
e. extensive information/the internet/find
f. our order/the waiter/took
g. the schedule/the participants/will distribute
h. the police/footprint/found
i. the children/the sandcastles/built
j. the father/the window/not going to open
B. Rewrite the following sentences in the passive voice using the correct form
of verbs in the brackets.
a. Call the ambulance! Two boys ……… (injure) in a motorbike accident.
b. The clock ………… (use) since the 17th century.
c. I had to wait outside the classroom while the classroom ……… (clean).
d. The problem ………… (discuss) by the subject specialists at the moment.
e. By the time I came back, the task …………… (finish).
f. Women ………….. (say) to be happier than men.
g. Look! The house ……….. (destroy) by the fire.
h. The other three reports………………… (submit) by next month.
i. Many people ………. (rescue) from the floods by the security persons this year.
j. The state of Florida ……………. (hit) by a hurricane that did serious damage.
Expressing counter arguments
A. Read the following conversation between two friends on animal testing and
notice the expressions of counter arguments.
A: Hi Pooja! How are things?
B: Fine, and you?
A: I’m feeling rather upset today. I could not see some animals being ripped
off alive in the science lab.
B: Well, I must say using animals as test subjects for health products is
A: As far as I am concerned, I take it as inhumane activity.
B: To be fair, animal testing has been used in the past to aid the development
of several vaccines, such as smallpox and rabies. However, animal testing
for beauty products causes unneeded pain to animals.
A: Don’t you think it is possible to use human volunteers instead of using
B: Exactly. Animals should not be exploited as far as possible.
B. Work with a small group to talk around the questions given below. Use the clues of expressing counter arguments from the box.
a. Is your hometown a good place to live?
b. What’s the best thing to eat in your city/village?
c. Is teaching your dream job?
d. Is it better to seek jobs in a foreign country?
e. Is the reservation of quota for a particular sex or caste a good thing?
From my point of view,
It seems to me…..
Personally, I believe/feel…..
What I reckon is…….
If you ask me……..
I’m convinced that ……..
Go to the forest or a garden and observe how plants, insects and animals depend on
each other. Present your observations in the class.
All Units Notes