Download File

Symbiotic
Relationships
Objectives of the Symbiotic
Relationships Lesson
 Students will investigate how organisms or populations
interact with one another through symbiotic
relationships and how some species have become so
adapted to each other that neither could survive
without the other. (Ohio Academic Standards LS 7.1)
 Students will be able to define and identify the following
relationships:
 Parasitism
 Mutualistism
 Commensalism
 Neutralism
 Competition
Symbiotic Relationships
 Definition: A relationship between two
kinds of organisms that lasts over a
period of time is called symbiosis.
 The word symbiosis can be broken down
into two parts to determine its meaning.
 sym means together (like in the words
sympathy and symphony)
 bio mean life (like in the words biology and
biome)
Parasitism
Parasitism
 Parasitism is the
situation where one
organism benefits
while the other is
harmed.
 A + / - relationship.
 Think of a friendship
where you might feel
used by your friend.
Parasitic Isopod on fish
Tapeworms
 The definitive host of the cucumber tapeworm is a
dog or a cat (occasionally a human). Fleas and lice
are the intermediate host. the dog or cat becomes
contaminated when the eggs are passed in the
feces, and the flea or louse ingests the eggs. The
dog or cat (or human) is infected when they ingest a
flea or louse. Hence the importance of controlling
fleas on your pet!
Bedbugs

Bedbugs are small,
nocturnal parasites that
come out of hiding at
night to feed on
unsuspecting
humans. They feed
exclusively on
blood! Their bites often
result in an allergic
reaction.
Acacia plant with ant galls
Ants lay eggs
on acacia tree
Acacia covers
the infected
area with
brown flesh
(gall)
Parasitism: one benefits, one is harmed
Taenia worm in human eye
Worm infects
human blood
stream
Human may
go blind
Parasitism: one benefits, one is
harmed
Commensalism
Commensalism
Commensalism
is
where one species
benefits
while
the
second
species
remains unaffected.
A + / 0 relationship
Think of a friendship
where one of the
friends benefits while
the other doesn’t
change.
Barnacles adhering to the skin of a
whale
Cattle with cattle egrets
Cattle stir up
insects as
they eat
grass
Egrets hang
around and
eat insects
Commensalism: one benefits, one is unaffected
Mutualism
Mutualism
 Mutualism is where
both organisms
benefit from the
relationship.
 A + / + relationship.
 Think of a normal
friendship where
both friends gain
The clownfish and sea anemone are an example of
mutualism. Although these anemones stun and devour something from the
other species of fish, clownfish are not harmed.
friendship.
Clownfishes were thought to be commensal on the
giant sea anemones, but there now is evidence that
the aggressively territorial clownfishes chase away
butterfly fishes, who eat anemone tentacles.
Mutualism
 Both organisms benefit from the
relationship
Otters and Kelp
The otters help the
kelp by eating the
sea urchins which
endanger it. The kelp
provides and anchor
for the otters while
they sleep.
Moray Eel with
Cleaner Fish
Moray Eel gets a
clean mouth
Cleaner Fish gets
a meal
Mutualism:
both benefit
Antelope with Oxbird
Antelope
gets rid of
parasites
Oxbird
gets a
meal
Mutualism: both benefit
Predation
What type of relationship is this? Can you guess?
The picture shows a shark going after the small fishes
to eat them. The small fishes are helpless! In this type
of relationship, the shark is the predator, much bigger
and powerful, while the small fishes are the prey. They
are directly attacked by the predator. This relationship
is called predation. Do you know of other examples of
this type of relationships?
Neutralism
 Neutralism is the situation
where both species remain
unaffected.
 A 0 / 0 relationship.
 Think of someone you sit
beside but never show any
emotional either positive or
negative.
Neutralism
Neutralism the most common type of
interspecific interaction. Neither population
affects the other. Any interactions that do
occur are indirect or incidental.
Example: the tarantulas living in a desert
and the cacti living in a desert
Competition
 Competition is where neither
species benefits.
 A - / - relationship.
 Think of someone whom you are
constantly at battle with.
COMPETITION:
Scramble (Indirect) vs. Contest (Direct)
Scramble: mutual use of limited resource
 -Most plant competition is of this form
Contest: interact directly (direct
aggression or display)
Competition can be defined as an interaction
between organisms or species, in which
the fitness of one is lowered by the presence of
another.
Limited supply of at least one resource (such
as food, water, and territory) used by both is
required. Competition is one of many interacting
biotic and abiotic factors that
affect community structure
intraspecific competition Competition among members of
the same species
interspecific competition.
competition between individuals of
different species is known as
Amensalism
Amensalism between two species involves one
impeding or restricting the success of the other while the other
species has no effect on it.
Do you know that there are organisms that may live
together only for sometime
because one species secrete a toxic or lethal substance that
could kill the other species?
Are you familiar with some of them? A certain species of
Artemisia (damong maria) secrete
a substance that can kill the grasses that may grow around
them. This is an example of
amensalism.
It is a type of symbiosis. Usually this occurs when
one organism exudes a chemical compound as part of its
normal metabolism that is detrimental to another organism.
The bread mold Penicillium is a common example of this;
penicillium secrete penicillin, a chemical that kills bacteria.
A second example is the black walnut tree (Juglans
nigra), which secrete juglone, a chemical that harms or
kills some species of neighbouring plants, from its roots.
This interaction may still increase the fitness of the nonharmed organism though, by removing competition and
allowing it access to greater scarce resources. In this
sense the impeding organism can be said to be negatively
affected by the other's very existence, making it a +/interaction.
A third simple example is when sheep or cattle make
trails in grass that they trample on, and without realizing,
they are killing the grass.
Saprophytism
Since one of the characteristics of fungi is
that they are unable to produce their own
food by photosynthesis, due to the lack of
choloroplasts, they obtain their food from
other organisms. They also do not have
mouths to take in food as animals do,
therefore they absorb food through their
plasma membranes and cell walls. One of
the types of such heterotrophic food intake
methods is saprophytism
Effects and examples
 They break down wastes from dead
organic matter and thereby enabling the
constituent materials to be available for
reuse by other organisms within the
ecosystem.
 dry rot, which occurs in wooden houses,
and other wooden structures, causing the
wood to deteriorate and the structure to
fall apart
Cannibalism
Cannibalism
Eating species of the same kind.
Example: Human (Holocaust)
Spider
dog eating puppies
Cooperation
Cooperation
 Helping same kind of organisms or
organisms of different kind to get food.
 Example: Ants in a colony
 honeybee colony where the
member carry out and follow
specific task rigidly and work
together for benefit of the group
For Practice
A lichen is a combination of two organisms, an
alga and a fungus. The fungus gets its food
from the alga while the alga gets water from
the fungus. This is an example of which
relationship?
a) Competition
b) Mutualism
c) Parasitism
d) Commensalism
Let’s look at this again
 If this were an example of competition,
both of the organisms would be effected
negatively. However, in this example
neither organism is effected negatively.
 Return to the question.
Good Job!
 You’re right! This is an example of a
mutualistic relationship. The alga gains
water from the fungus and the fungus
gains food from the alga. Both need each
other to live and gain something from the
other organism.
 Go to the assignment
It’s interesting that you
think this
 In a parasitic relationship, one organism
gains a positive while the other organism
receives a negative. In this example,
neither organism receives a negative.
 Return to the question.
Can we talk about the
example
 In a commensalistic relationship, one
organism gains something positive. The
other organism remains unaffected by
the relationship. In this example, both
organisms are effected by the
relationship.
 Return to the question.
X Y
Type of interaction
0 0 Neutralism
- 0 Amensalism
+ 0 Commensalism
- - Competition
+ + Mutualism
+ - Predation orParasitism
Terminology
 Herbivory: an animal consuming plant
material
4 kinds of herbivores:
 Grazers (aka folivores) consume leafy
material
 Browsers consume woody material and
bark
 Granivores consume seeds
 Frugivores consume fruit