The difference between regular and irregular echinoids 0.0 / 5 ? Geologyechinoids A2/A-levelAll boards Created by: naomiCreated on: 05-01-14 14:32 46851031297 Across 1. Shape of ambulacra and pore pairs: ambs petaloid on top surface online, one pair of pores per plate, pores round and close set except when respiratory tube feet present - then may be elongated (9) 6. Anterior groove: present (9) 7. Shape: Hemispherical/round/dome (7) 8. Position of mouth: centre of oral surface (bottom), contains jaws (7) 9. Size of tubercles: tubercles large, well spaced out (7) Down 2. Labrum: not present (7) 3. Fasciole: not present (7) 4. Position of mouth: lies either in centre of oral surface or towards anterior margin and lacks jaws (9) 5. Anterior groove: not present (7) 10. Position of anus: in centre of apical system in centre of aboral surface (7)
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