The Echindermata Flashcards
What was the time period of the Echindermata?
Cambrian to recent
What does deuterostoma mean?
The anus is developed before the mouth.
Where do they primarly live?
They’re benthic - live on the sea floor.
What are their skeletons composed of?
Their skeletons are composed of monocrystalline porous calcite plates.
Where’s does their skeleton’s lie within their bodies?
It’s mesodermic - their skeleton’s lie underneath a thin layer of skin.
Explain what the water vascular system is?
Water enters though the stone canal and this water fills up the muscle allowing it to contract/expand using hydrostatic pressure.
Croinoids and star fish have what type of symmetry?
They have pentameral - five fold symmetry.
What time period did croinoids live in?
Cambrian to recent
Croinoids feed on what?
They’re filter feeding organisms which use their branchials to filter food - also they use these to move.
Which marine environment did croinoids used to live in?
They used to live in open seas.
What is the Latin name for sea urchins?
Eleuthrozoans
What timescale did Eleuthrozoans live in?
Ordovician - recent
What type of symmetry do regular Echinoids have?
They have pentameral symmetry
Explain their body structure - regular Echinoid.
They have a periproct in the centre of their body, 5 different interambulacral areas and 5 different ambulacral areas. Covering all of these area are podia.
What’s the ambulacral system?
This is the water vascular system in Echinoidea.
What are spikes on Echinoids for?
They’re used for self defence, some splinter and use poison in order to defer predators
What symmetry do irregular Echinoids have?
They have bilateral symmetry
What time scale did the irregular Echinoids live from/in?
Jurassic - recent.
Describe the form/features of irregular Echinoids.
They have a mouth flattered towards the front and an anus towards the rare. They have a flattened form and use a grooved ambulacrum to help direct sediment.
How do Irregular Echinoids respire and excrete waste?
They breathe though tube feet sticking out of the sediment, leaving waste behind though sanitary drains.
How have irregular Echinoids evolved through time?
They’ve changed shape and become a lot flatter, also their peristome is now reduced in size.
