Can plants live without animals? Why or why not?

Hi Patty,

Thank you for your interesting question.  As a first thought, it
appears that plants do not need animal to live.  After all, we animals
use plants for tons of purposes: food, wood, etc.

However, on closer examination, we shall see that many plants depend
on animals for their existence, and thus many of them would not be
able to survive without animals.

1) The Venus's-flytrap (Dionaea muscipula) is one of the best-known
examples of meat-eating plants.  It lives in areas where there are not
enough nutrients, thus it needs to trap animals to obtain the needed
nutrients.

2) Pollination in flowering plants depends on the help of animals. 
"As sedentary organisms, plants usually must enlist the services of
external agents for pollen transport."  Animals, especially bees,
pollinate plants by carrying pollen from one flower to another.

3) Seed dispersal also depends on animals.  Plants strive to make
their fruits as enticing as possible so that animals would eat their
plants and carry the seeds far away.

4) Browsing, or eating the young shoots, leaves, and twigs of plants
keep dominant species of plants in check.  Without browsing, more
dominant plants would take over and thus killing off the less dominant
ones.

So in conclusion, to a lesser extent, plants do rely on animals for
their survival.

Search strategy:
"plants need animals"

Sources:
http://www.seps.org/oracle/oracle.archive/Life_Science.Ecology/2001.08/000998160004.17260.html

http://www.hctf.ca/wild/resources/projectwild/activity.htm

Encyclopędia Britannica Online, "Venus's flytrap"
Encyclopędia Britannica Online, "Pollination"

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Clarification of Answer by secret901-ga on 04 Aug 2002 10:24 PDT

If you need clarification, please request for it before rating the answer.
Thank you,
secret901-ga

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Clarification of Answer by secret901-ga on 04 Aug 2002 10:46 PDT

Oops, I forgot to mention that animal decay turn into nutrients and
serve as nutrients for plants as well.

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Clarification of Answer by secret901-ga on 04 Aug 2002 15:12 PDT

Thanks knowledge_seeker and jeremymiles for your input.  I have
overlooked the fact that animals produce CO2, which is essential in
photosynthesis. Also, it is true that plants existed before the first
animals appeared on Earth.  However, those plants are extremely
primitive.  As I have said before, many plants do depend on animals
for their existence, but many do not.  Plants depend on animals to a
lesser extent than do animals depend on plants.

Not to mention the most obvious reason plants need animals ... we
exhale carbon dioxide (CO2) that plants need in order to "breathe." 
(they don't really "breathe" in the sense that we do, but they need
CO2 to make energy)

The converse is also true, they "exhale" or give off oxygen that we
need to breathe. Neither of us can live without the other.

-K~ (speaking for the Lorax today :-) )

I wouldn't disagree with anything said in the answers so far, but
don't forget that there were plants before there were animals, so the
short(est) answer must be 'Yes'.

Jeremymiles-ga,

Are you sure that plants were here before animals?

A plant is an extremely complex lifeform composed of many specialized
cells.
Before the first plant there were common single-celled organisms such
as amoebas and bacteria. Both of these are classified as animals....

egri

Amoebas and Bacteria are not classified as animals.

See http://tolweb.org/tree?group=Eukaryotes&contgroup=Life

Also, if you would like a more in-depth discussion of phylogenetics see:

http://www.ucmp.berkeley.edu/exhibit/phylogeny.html

Best

Eventhough it might sound most obvious that plants would need animals
as for their source of co2, it isn't actually so. Plants get their co2
from other plants, as they decay (slowly burn) when they die.
Chemicallys speaking a carbon-based tree combines with oxygen creating
carbon dioxide (burns). So the plants are quite self-sufficient with
their own cycle of co2.

Thanks to cephalic for reminding me there are more kingdoms than
plants and animals. :-)