Adaptations for Movement
- Movement is a unifying feature of all living organisms
- The way in living organisms move varies hugely with some organisms being more motile and others being more sessile
Motile Organisms
- Motile organisms are those that are capable of moving from place to place (you will be familiar with many organisms that have this trait)
- Note that all motile organisms can also exhibit movement shown by sessile organisms, this means that internal parts of their bodies can move in response to stimuli e.g. peristalsis in the digestive system
- Many living organisms are motile, such as the majority of members of the animal kingdom, many bacteria, particularly those which are predatory
Sessile Organism
- Sessile organisms cannot move from place to place but are able to move parts of their body in response to environmental stimuli
- This type of movement might include orientation of plant stems towards the sun or movement of cytoplasm within a unicellular organism
- Some animals are sessile including:
- Sponges, corals and anemones
- Most fungi species
- All plant species
Examiner Tip
You are required to know one example of a motile species and one example of a sessile species for your examination.
