Types Of Skeletons Flashcards
What do animals need to be able to move?
Support systems
What does a skeleton do?
Offers support and allows the animal to move
How is an animal’s skeleton adapted?
To its environment
Its mode of nutrition
What kind of support does an aquatic animal need?
Less than an animal
Why do aquatic animals need less support than land animals?
The water provides some support
What affects the required effectiveness of a skeleton?
The larger and more complex the animal, the more support the animal will need
What are the three types of skeletons?
Hydrostatic
Endoskeleton
Exoskeleton
What is a hydrostatic skeleton?
A fluid-filled cavity surrounded by muscles
How does an animal with a hydrostatic skeleton move?
The fluid exerts pressure
The muscles contract
This changes the shape of the animal
This brings about movement
What kind of animals have a hydrostatic skeleton?
Invertebrate animals with soft bodies
Which animals have a hydrostatic skeleton?
Jellyfish Sea anemones Earthworms Flatworms Roundworms
What are some advantages for a hydrostatic skeleton?
The animal is very flexible
The animal does not need a specialised support system, since these types of animals usually live in water
What are some disadvantages of a hydrostatic skeleton?
It does not allow for fast movements
Can only occur in moist environments
Limits the size of an animal
Does not provide much protection
What is an exoskeleton?
A skeleton that exists on the outside of an animal’s body
What kind of animals have an exoskeleton?
In many invertebrates
Give an example of a group of animals that have exoskeletons?
Arthropods
What is an exoskeleton made of?
A polysaccharide called chitin
Often strengthened with calcium carbonate
What are some advantages of an exoskeleton?
Protects underlying tissues from injury
The skeletons provide a place of attachment for muscles; this allows for quick movements
This type of skeleton prevents dessiccation
What is dessiccation?
Drying out
What are some disadvantages to an exoskeleton?
Size is limited
Growth is difficult
It is impermeable to gases
Why is size limited by an exoskeleton?
The bigger the animal, the heavier the skeleton, the harder it is to move
How is growth limited by an exoskeleton?
Chitin cannot stretch
The animal has to shed its skeleton during growth periods
This new skeleton is soft and leaves the animal vulnerable
What is it called when an animal sheds its exoskeleton?
Moulting
What is an endoskeleton?
An internal skeleton
What are endoskeletons made of?
Bone
Cartilage
What are some advantages to an endoskeleton?
Growth is possible It protects important organs It gives good structural support Gives shape to the body Provides a place of attachment for muscles Flexibility is possible
How is growth possible within an endoskeleton?
Bone and cartilage are living tissues, so they can grow with the organism
How does an endoskeleton provide flexibility?
Joints between bones allow for freer movement
What is a disadvantage of an endoskeleton?
It does not provide much protection from the outside world, so desiccation is possible
What are vertebrate animals?
Animals that have a vertebral column
i.e. They have an internal skeleton consisting of bone and/or cartilage
What kinds of animals are vertebrates?
Fish Amphibians Reptiles Birds Mammals
What are invertebrate animals?
Animals that do not have a vertebral column
Which animals are invertebrates?
95% of all animal species
