Crinoids

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Phylum
Echinodermata
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Class
Crinoidae
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Water vascular system
system of internal hydraulics that operate tube feet for movement and feeding etc.
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Five fold symmetry
structures arranged in multiples of five
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Test made of...
Calcite plates
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Radial plates
on calyx- point of attachment for arms
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Basal plates
on calyx- structural
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Infrabasal plates
on calyx- attach calyx to stem
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evolution
First evolved in Ordovician. Peaked in upper Paleozoic (early carboniferous). Are extant
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Environment
moderate energy (filter feeders). Above and below photic zone
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Mode of life
Fossil crinoids= sessile- holdfast attached to seabed. Some vagrant
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Brachia
delicate structures that waft in currents and use cilia to collect food particles. Flexible arms.
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Calyx
cup made of flat calcareous plates which contain soft body of animal-five fold symmetry
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Stem
made of calcite ossicles with centres linked together with soft tissue
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Hold fast
attaches to substrate - if on hard substrate they secrete cement to attach at base of stem
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Anal tube
from centre of calyx- gets rid of waste without mixing with fresh water
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membrane
soft tissue covering animal to protect calcite-flexible. Decays on death and so animal becomes disarticulated
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to eat
pinnules of brachial catch food particles which get passed down food grooves by cilia into the mouth
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Tegmen
for feeding. on top of calyx and hosts mouth in centre-five radial food groves and **** on side
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Other cards in this set

Card 2

Front

Crinoidae

Back

Class

Card 3

Front

system of internal hydraulics that operate tube feet for movement and feeding etc.

Back

Preview of the back of card 3

Card 4

Front

structures arranged in multiples of five

Back

Preview of the back of card 4

Card 5

Front

Calcite plates

Back

Preview of the back of card 5
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