support and movement Flashcards
(14 cards)
What supports animals and enables movement?
Support systems, usually in the form of a skeleton, support animals and enable movement.
What are the three types of skeletal systems?
- Hydrostatic skeletons 2. Exoskeletons 3. Endoskeletons
What is a hydrostatic skeleton?
A hydrostatic skeleton consists of fluid-filled, closed chambers inside the body that provide support for muscle contraction and movement.
What types of animals have hydrostatic skeletons?
Hydrostatic skeletons occur in soft-bodied invertebrates such as coelenterates (e.g., jellyfish, anemones), annelids (e.g., earthworms), and nematodes (e.g., roundworms).
How do animals with hydrostatic skeletons move?
They contract muscles surrounding the fluid-filled cavity, creating pressure that changes the shape of the animal, allowing movement such as burrowing, crawling, or swimming.
How do jellyfish move?
Jellyfish move by contracting their bell-shaped form, forcing water out, which propels them forward.
What is an exoskeleton?
An external structure that supports the animal and protects its internal organs from injury.
Exoskeletons are found in many animal groups, but arthropods are the main group with exoskeletons.
What is the main component of an arthropod exoskeleton?
Chitin, a polysaccharide similar to cellulose found in plant cell walls.
Chitin is light and strong, making it suitable for an exoskeleton.
List the advantages of an arthropod exoskeleton.
- Supports the animal
- Protects internal organs
- Muscles attached for movement
- Joints for flexibility
- Covered with cuticle to reduce water loss
The cuticle helps prevent dehydration.
When did exoskeletons first appear in the fossil record?
About 550 million years ago.
This marks a significant evolutionary development.
What are the disadvantages of exoskeletons?
- Limit mobility
- Limit growth
A large animal would require a heavy exoskeleton, restricting its movement.
How do arthropods overcome growth limitations due to exoskeletons?
By shedding their exoskeletons in a process called moulting or ecdysis.
A new exoskeleton is regenerated by the underlying epidermis.
What happens after an arthropod sheds its exoskeleton?
It pumps air or water to expand the new exoskeleton and then dehydrates the cuticle to harden it.
This process makes them vulnerable to predators.
How do many mollusks grow their shells?
They add to the diameter of their calcareous shells without altering their shape.
This allows for growth while maintaining shell integrity.
