Unicellular organisms are made up of one cell. :) That is not a lot.
Ok. As their body is just one cell they do not have any systems like multicellular organisms, (eg. respiratory system) and have to deal with many processes just within that one cell.
What are these things?
- obtaining/synthesising their own food/raw materials
- all their functions must be carried out by sub-cellular structures
- excreting/secreting their waste materials
I supposethat it happens through their membrane?
As you can guess these organisms have to be really small. In most cases unicellular organisms are microscopic. However there are some exemptions. As always.
Valonia Ventricosa also known as sailor's eyeballs.
It is giant i the world of unicellular organisms. Usually its diameter is between 1 and 4 cm (it can be even bigger than that). Not a lot? Another representative of unicellular world is bacteria. Lets say that its size is 2 micrometers. Which is 0.0002 cm. It means that our lovely Valonia is 20,000 times bigger than bacteria. When blue whale can be 100 bigger than human. Only!
Lets have a quick look at other unicellular organisms.
Paramecium - aquatic animal-like organism
Euglena -some of Euglena spiecies have animal and plant characteristics. They contain
chloroplast like animals and have flagellum for motion. I personally like Euglena a lot as it is green on all the pictures that I have seen and I love everything that is green.
Chlorococcum - It is a type of algae that contains one big chloroplast inside hence it is GREEEN!
And our friends and anemies - Bacteria - theses little creatures are a little bit different from above examples. Bacteria is prokaryotic (I may touch this subject later) which means that are not only very very small but also very very simple living creatures.
Enough for today. I have revision test tomorrow.
