Biology
The Skeleton Notes
There are three types of skeletons…
- Hydrostatic skeleton
- Exoskeleton
- Endoskeleton
What are Hydrostatic skeletons:
- Jellyfish, anemones, earthworm, roundworm, star fish and snail.
(coelenterates, annelids, nematodes)
- Uses buoyancy of water.
- A disadvantage
= Is that it loses water (desiccation) causing it to die.
= Lack well developed skeletal defence mechanisms
= Restricted range of movement
= Cannot reach any great size.
= Are confined to areas near or in water as they lose water easily.
- An advantage
= Is that it does not waste energy on creating a skeleton.
- Consists of fluid filled, closed chambers within an organism.
- This provides support against which muscles can contract to bring about
movement.
- Like a water filled balloon.
- Also helps to cushion internal parts from shock.
- Often in soft bodied invertebrates.
- Good for aquatic animals.
- Move by contracting the muscles surrounding the fluid filled cavity creating
pressure causing a change in shape of the animal. (movement like
burrowing, crawling or swimming.)
- Jellyfish move by contracting their bell-shaped form, forcing water out of
the bell, this propels the jellyfish forward.
, - Earthworms use this skeleton to change their body shape as they move
forward by peristalsis. Circular and longitudinal muscles produce
movement through waves of contraction and relaxation. When lengthwise
muscles contract, segments of the body shorten; when circular muscles
contract segments of the body elongate. Chaetae (bristles) press into the
ground to help the earthworm move forward.
What are Exoskeletons:
- Beetle, spider(arthropods), tortoise, corals, star fish and molluscs with
shells, lobster, bee, snail.
- Also called ectoskeleton.
- On the outside of the body.
- Made up from a protein called Chitin, it is a light and quite strong
compound. (polysaccharide)
- A disadvantage
= Is that it outgrows its skeleton frequently. ( called Molting or Ecdysis, they
lose it because it becomes too small.)
= Have limited mobility.
= Have a growth limit.
- To help movement restrictions the skeleton is divided into different
functional units ( head, thorax and abdomen of insect.) and have joined
limbs where the exoskeleton is thin at the joints for the leg to move.
- An advantage
= It is an external structure that supports the animal and protects its
internal organs from injury.
= Has muscles attached to knobs and plates for movement.
as joints that are thin and flexible to move more easily.
= Often covered with a layer of wax called a cuticle that reduces water loss
from the body, preventing the animal from drying out.
What are Endoskeletons:
- Humans and animals.
- It is covered by tissue.
- Has muscles and tendons and ligaments.
- Also contains cartilage.
- Found within the body.
- All vertebrates have an endoskeleton.
- Skeleton made of bone and/or cartilage.
- An advantage
= Supports the body, giving it shape.
= Made of living tissue that grows as the animal increases in size.
= Protects the internal organs like the brain, lungs and heart.
= Provides anchors for muscles which work with bone for movement.
= Grows with your body.
What is Cartilage:
The Skeleton Notes
There are three types of skeletons…
- Hydrostatic skeleton
- Exoskeleton
- Endoskeleton
What are Hydrostatic skeletons:
- Jellyfish, anemones, earthworm, roundworm, star fish and snail.
(coelenterates, annelids, nematodes)
- Uses buoyancy of water.
- A disadvantage
= Is that it loses water (desiccation) causing it to die.
= Lack well developed skeletal defence mechanisms
= Restricted range of movement
= Cannot reach any great size.
= Are confined to areas near or in water as they lose water easily.
- An advantage
= Is that it does not waste energy on creating a skeleton.
- Consists of fluid filled, closed chambers within an organism.
- This provides support against which muscles can contract to bring about
movement.
- Like a water filled balloon.
- Also helps to cushion internal parts from shock.
- Often in soft bodied invertebrates.
- Good for aquatic animals.
- Move by contracting the muscles surrounding the fluid filled cavity creating
pressure causing a change in shape of the animal. (movement like
burrowing, crawling or swimming.)
- Jellyfish move by contracting their bell-shaped form, forcing water out of
the bell, this propels the jellyfish forward.
, - Earthworms use this skeleton to change their body shape as they move
forward by peristalsis. Circular and longitudinal muscles produce
movement through waves of contraction and relaxation. When lengthwise
muscles contract, segments of the body shorten; when circular muscles
contract segments of the body elongate. Chaetae (bristles) press into the
ground to help the earthworm move forward.
What are Exoskeletons:
- Beetle, spider(arthropods), tortoise, corals, star fish and molluscs with
shells, lobster, bee, snail.
- Also called ectoskeleton.
- On the outside of the body.
- Made up from a protein called Chitin, it is a light and quite strong
compound. (polysaccharide)
- A disadvantage
= Is that it outgrows its skeleton frequently. ( called Molting or Ecdysis, they
lose it because it becomes too small.)
= Have limited mobility.
= Have a growth limit.
- To help movement restrictions the skeleton is divided into different
functional units ( head, thorax and abdomen of insect.) and have joined
limbs where the exoskeleton is thin at the joints for the leg to move.
- An advantage
= It is an external structure that supports the animal and protects its
internal organs from injury.
= Has muscles attached to knobs and plates for movement.
as joints that are thin and flexible to move more easily.
= Often covered with a layer of wax called a cuticle that reduces water loss
from the body, preventing the animal from drying out.
What are Endoskeletons:
- Humans and animals.
- It is covered by tissue.
- Has muscles and tendons and ligaments.
- Also contains cartilage.
- Found within the body.
- All vertebrates have an endoskeleton.
- Skeleton made of bone and/or cartilage.
- An advantage
= Supports the body, giving it shape.
= Made of living tissue that grows as the animal increases in size.
= Protects the internal organs like the brain, lungs and heart.
= Provides anchors for muscles which work with bone for movement.
= Grows with your body.
What is Cartilage:
