Echinodermata
Spiny-skinned animals with a hard internal skeleton.
Starfish on a beach
A starfish is a spiny-skinned animal.
What do you think gives it protection and controlled movement?
What this lesson covers
The idea
Echinoderms lack a notochord but have a hard internal skeleton of calcium carbonate that gives them protection and controlled movement.
Starfish on a beach
A starfish is a spiny-skinned animal.
What do you think gives it protection and controlled movement?
- A hard skeleton inside the body
- A shell outside the body
- A notochord
Inside an echinoderm
Open each tab.
Support from inside
Echinoderms are non-chordates, but their hard internal skeleton gives them protection and controlled movement. Their body organisation is quite like that of more complex animals, showing a gradual shift towards internal skeletal support.
Echinoderms lack a notochord but have a hard internal skeleton of calcium carbonate that gives them protection and controlled movement.
Notes
Echinoderms lack a notochord but have a hard internal skeleton of calcium carbonate that gives protection and controlled movement.
Check yourself
Which animals are echinoderms?
What is the skeleton of an echinoderm made of?
Where is the skeleton of an echinoderm?
Do echinoderms have a notochord?
- Snails and octopuses. These are molluscs.
- Starfish and sea urchins — correct. Yes!
- Hydra and jellyfish. These are cnidarians.
- Chitin. Chitin is found in the cell walls of fungi.
- Cellulose. Cellulose is found in the cell walls of plants.
- Calcium carbonate — correct. Yes!
- Inside the body — correct. Yes!
- Outside the body, like in arthropods. Arthropods have a hard external skeleton. Echinoderms have an internal skeleton.
- There is no skeleton. Echinoderms have a hard internal skeleton.
- Yes, as protochordates do. Protochordates have a notochord. Echinoderms lack one.
- No, they lack one — correct. Yes!
- Yes, they are chordates. Echinoderms are non-chordates because they lack a notochord.