How spatangoids produce their traces: relationship between burrowing mechanism and trace structure
Version of Record online: 9 OCT 2007
Volume 28, Issue 3, pages 211–219, September 1995
How to Cite
KANAZAWA, K. (1995), How spatangoids produce their traces: relationship between burrowing mechanism and trace structure. Lethaia, 28: 211–219. doi: 10.1111/j.1502-3931.1995.tb01424.x
- Issue online: 9 OCT 2007
- Version of Record online: 9 OCT 2007
- Received 20th June, 1994 revised 10th February, 1995
Kanazawa, K. 1995 11 30 How spatangoids produce their traces: relationship between burrowing mechanism and trace structure.
Two spatangoid echinoids, Echinocardium cordatum and Lovenia elongata, were allowed to produce their traces in poorly and well-sorted sediments in aquaria. In poorly sorted sediments they formed distinct traces, comparable to fossil traces. Sorting of sediment occurred during transportation by the lateroventral spines and brought about characteristic patterns in grain size at the bottoms of the burrows and in redeposited sediment, which made the traces visible. Differences in the burrowing mechanism between E. cordatum and L. elongata are reflected in their trace structures. E. cordatum formed a laminated backlill structure which resulted from periodic accumulation of excavated sediment behind it, while L. elongata simply pushed excavated sediment by compression to the posterior sides of the test, so that their traces lack a distinct laminated structure and the width of the trace becomes larger than that of the animal. In well-sorted sediment, the echinoids burrowed in the same way as in poorly sorted sediment, but no visible trace was produced other than a drain tube. These observations reasonably explain some characteristic modes of occurrence of fossil spatangoid traces. Their different morphological expressions depend on sediment texture and the uneven lithification of traces. Spatangoids, trace, burrowing mechanism.