Relationships of Living things

All living things within an ecosystem interact in many different ways.

They can….

•Hunt together in packs

•Stick together for safety

•Defend each other against harm

•Huddle for warmth

•Share food supplies

..Or… •For food

•For space

•For mates

•For light

•For power/dominance

Collaborate Compete

Whether they are in or if the organisms are from the same species their relationship is known

as….

….and if the organisms are from different species their relationship is known as…

And a handy general term to describe an intimate relationship between organisms is…

Let’s look at the different kinds of relationships between species according to the outcomes for

those species involved…..

What are the possibilities?

One is Harmed

One Gains One Gains

One is indifferent

BothGain

1. Predator/Prey relationship

2. Parasite/Host relationship

4. Mutualism

5. Commensalism

3. Allelopathy

Let’s begin with a simple food chain….

..or if we want to look at trophic levels…..

….or if we want to look at it terms of predator/prey…

Prey (rarely Predator)

Prey & Predator

Prey & Predator

Top Predator

•Producer•1o Consumer

•Herbivore

•2o Consumer

•1 o Carnivore

•3o Consumer

•2o Carnivore

1st trophic level

2nd trophic level

3rd trophic level

4th trophic level

1) Predator/Prey Relationships

This type of relationship is severe as one organism – the prey - is killed to benefit the other – the predator. There can be 4

different outcomes for the groups of predators or prey:

Both predator and prey die

Predator dies and

prey lives

Predator lives and prey dies

Both predator and prey live

Which is the most beneficial to both organisms?

Each of the four graphs on your worksheet shows one of these 4 outcomes – can you identify them?

1) Predator/Prey Relationships

Predators:

•Usually less abundant than prey

•Compete for prey and so can adapt to do so better. For example echolocation

in bats

•Collaborate by hunting in packs

Prey:

•Usually more abundant than

predators

•Need to defend themselves can

employ a series of methods;

a)Counter attack

b)Mimicry

c)Camouflage

Some examples…

1) Predator/Prey RelationshipsCounter attack:

•Can take a huge variety of forms and can be adaptations that are physical, behavioural or physiological

•Aim is to defend prey from predator

•Examples include:

•Horns, antlers

•Offensive smells

•Tough outer shells

•Burrowing

•Speed

•Poisons

How does this squid counter attack?

Squirts out black ink to confuse the

predator!!

Counter Attack

A female insect protects her eggs with sharp crystals. Breathing or eating these crystals could be fatal to another insect. X2,000

1) Predator/Prey Relationships

1) Predator/Prey Relationships

Mimicry – When organisms copy or imitate each other. Can be two types:

Mullerian mimicry is when poisonous

organisms share the same warning

patterns or colours.

Examples are the patterns of black with yellow or orange used

by frogs, bees and monarch butterflies.

Batesian mimicry is when the organism is not

poisonous but copies or mimics the poisonous one. It is behaving like a fraud.

Examples are caterpillars looking like vipers or octopuses mimic sea

snakes by swimming with equal number of tentacles in front as well as behind

them.

1) Predator/Prey Relationships

Camouflage is when an organism hides itself in or around its surroundings and blends in by taking on a similar appearance. The organism can do this by using colour, shape or texture.

Examples include stick insects, pepper moths, chameleons, (the game ‘Where’s Wally’ works on the camouflage principle).

Not good camouflages!!

Better!!

2) Parasite/Host RelationshipsThis common form of symbiosis, consists of one organism benefiting to the detriment of another.

There are two forms:

This is when the parasite lives

outside the host body.

Examples include ticks, fleas and

fungal skin infections

EndoparasitismEctoparasitism

This is when the parasite lives

inside the hosts body.

Examples include tapeworm, liver flukes, bacteria

and viruses

•Fleas are parasites because they suck blood from other animals.

•Usually a particular species of flea will bite a different kind of animal, unless they get really hungry!

•Their cuticle has to be thick as their host is always trying to kill them.

•Many bug sprays will kill the adult but not the eggs, so fleas are hard to get rid of.

•Note the small eyes. Why don’t they need good eyesight?

•Their bodies are narrow to fit easily through hair and fur.

•Fleas can spread disease - the most famous being the plague or Black Death.

x180

2) Parasite/Host Relationships

3) Allelopathy

•This is a relationship where one organism directly hinders or stops the growth of another by releasing chemicals

•It occurs most often between plants and botanists initially thought it was simply competition of resources that allowed one species to dominate an area over another

•Now, agriculturalists are exploring the possibility of using allelochemicals as growth regulators and natural pesticides for crop growing

3) Allelopathy

Plants can release allelochemicals through the roots...

…or through the leaves

3) Allelopathy

•Several species of sage (Salvia) use chemicals to inhibit the growth of other vegetation. Sage is often surrounded by bare areas separating them from adjacent grasses, they grow into the bare areas pushing grasses further back. The chemical that is produced by the sage leaves gives it the quality of a spice.

•Another example of allelopathy is the production of flammable oils by eucalyptus trees; the oils promote frequent fires, which kill seedlings of competitors

4) Mutualism

Mutualism is a form of symbiosis when both organisms in the relationship benefit. Examples include:

• Fish swimming together in shoals

•Small fish who clean parasites from the gills of larger predator fish

•Pollinators and seed dispersers

•Microscopic organisms that help larger herbivores digest cellulose

4) Mutualism

This pollen has a prickly coat that sticks to insects better than smooth pollen, this improves its chances of reaching another flower. X3,000

•Pollinators carry pollen from one plant to another:

•Plant benefits from pollinator (insect or bird) by having pollen carried to another plant for cross fertilization

•Pollinator benefits from the plant by directly eating the pollen or by inadvertently taking pollen while feeding on plants nectar

•Pollen can adapt to increase their chances of hitching a ride

•Pollinators can adapt to collect more pollen

Female bees comb pollen between hairs that grow in rows on their back legs. One worker may collect millions of pollen grains in a single trip. The bees feed the larvae the pollen (as well as the honey made from nectar). X1,000

Hooks on a burdock seed pod can attach themselves to passing animals, including people, who spread the seed far and wide. x174

4) Mutualism

•Seed dispersers carry seeds away from the plant:

•Plant benefits as it has a chance to reproduce and spread its species

•Dispersers (usually a bird) benefit as they can eat the seeds

•Seeds can adapt so they have greater chance of sticking to their disperser and travelling great distances

Did you know that Velcro was modelled on these seed hooks and looks almost the same under the

electron microscope?

5) Commensalism

•This form of symbiosis is usually very hard to define as scientists don’t always understand fully the relationships between organisms.

•Examples could include:

•Trees that support other vegetation – orchid seeds rest on branches and grow from there

•Soft bodied sea dwelling animals that use discarded shells to live in

•Clown fish and poisonous anemones

Biological Control

Biological control is when scientists use one organism to control the population of another by

introducing them in close proximity. What kind of symbiotic relationship does this exploit?

Examples include:

•The cane toad (1935) introduced to control sugar pests

•Weevils (1980) to control weeds

•Myxomatosis (1950) to control rabbits

•Calicivirus (1996) to control rabbits

•Moth (1925) to control prickly pear

Successful?

No

No

Yes

Yes

Yes

Biological Control……an example

Aphids use their proboscis to suck the juices from leaves. They can be killed by poisons, but some

gardeners prefer to use ladybugs that can eat aphids in their thousands.

Aphid cornicles provide the one defense system aphids have against ladybugs. When attacked they squirt a sticky cement which sticks the ladybug to the leaf and gums up

its wings so it can’t fly away. x250

EM of an aphid x68

..but…

What is another biological term for this kind of defence the aphid has against its

predator the ladybug?

Counter Attack!!

The End!