Crinoids 4.5 / 5 based on 3 ratings ? GeologyFossilsA2/A-levelOCR Created by: ellenioannouCreated on: 03-03-15 09:23 Phylum Echinodermata 1 of 19 Class Crinoidae 2 of 19 Water vascular system system of internal hydraulics that operate tube feet for movement and feeding etc. 3 of 19 Five fold symmetry structures arranged in multiples of five 4 of 19 Test made of... Calcite plates 5 of 19 Radial plates on calyx- point of attachment for arms 6 of 19 Basal plates on calyx- structural 7 of 19 Infrabasal plates on calyx- attach calyx to stem 8 of 19 evolution First evolved in Ordovician. Peaked in upper Paleozoic (early carboniferous). Are extant 9 of 19 Environment moderate energy (filter feeders). Above and below photic zone 10 of 19 Mode of life Fossil crinoids= sessile- holdfast attached to seabed. Some vagrant 11 of 19 Brachia delicate structures that waft in currents and use cilia to collect food particles. Flexible arms. 12 of 19 Calyx cup made of flat calcareous plates which contain soft body of animal-five fold symmetry 13 of 19 Stem made of calcite ossicles with centres linked together with soft tissue 14 of 19 Hold fast attaches to substrate - if on hard substrate they secrete cement to attach at base of stem 15 of 19 Anal tube from centre of calyx- gets rid of waste without mixing with fresh water 16 of 19 membrane soft tissue covering animal to protect calcite-flexible. Decays on death and so animal becomes disarticulated 17 of 19 to eat pinnules of brachial catch food particles which get passed down food grooves by cilia into the mouth 18 of 19 Tegmen for feeding. on top of calyx and hosts mouth in centre-five radial food groves and anus on side 19 of 19
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