# Wikijunior:Biology/Creatures


## Creatures

Many different creatures live on earth: plants, insects, birds, fish,
bacteria, humans and many more. They have many differences and
similarities.

<File:Monkey> of kembang island.jpg\|thumb\|Monkey <File:Pterois>
volitans Manado-e edit.jpg\|thumb\|Pterois volitans <File:Marabou> Stork
at Animal Kingdom Lodge.jpg\|thumb\|Marabou Stork <File:Jelly>
Monterey.jpg\|thumb\|Jelly Monterey <File:Common> carder
bee.jpg\|thumb\|Common carder bee
<File:Euglena.gracilis.jpg%7Cthumb%7CEuglena>

## Are living beings related to each other?

*According to the theory of evolution, all living beings on earth are
related to each other.*

We humans are therefore related to monkeys, cows and apple trees, but
also to mosquitoes and bacteria. All living organisms on earth today
share common ancestors.

## Tree of life

<File:Tree> of life by Haeckel.jpg\|thumb\|Tree of life by Haeckel
<File:Circular> timetree-of-life 2009.jpg\|thumb\|ohne\|Circular
timetree-of-life 2009

In 1879, the biologist **Ernst Haeckel** drew a family tree of living
things inspired by the family trees of noble families. At the roots are
the unicellular organisms, from which all higher living beings descend,
with humans at the top. Scientists are aware that scientific statements
can be wrong and therefore look for errors. They found errors in
Haeckel\'s picture. So, the birds are drawn in the wrong place.

Modern family trees are much more complex. Humans are now on a par with
other living organisms. On the left of the picture are the mammals, next
to them are the birds. One of the lines denotes the humans. Extinct
creatures such as dinosaurs are not shown here. Even the modern family
trees are probably wrong. Viruses can transfer genes between different
organisms and protozoa can exchange genes with other protozoa. There are
many unanswered questions, especially in the case of unicellular
organisms. There is still much to explore for future biologists.


