A trab is a structural element within a sponge formed by the fusion of dendroclones.
In the Anthaspidellidae, when spicules (usually dendroclones) connect at their tips to form a ladder-like structure, trabs may be formed.[1]Oxeas are sometimes employed in the central rod.[1][2] Trabs have a feather-like structure, or may form rods.[1][3]
Trabs are usually regularly spaced, usually at sub-millimetric intervals.[1] Further dendroclones may interconnect adjacent trabs, forming ladder-like structures.[2]
The presence and alignment of trabs is often related to the internal structure of canals within sponges.[4][verification needed]
^ abcdKruse, P. (1983). "Middle Cambrian 'Archaeocyathus' from the Georgina Basin is an anthaspidellid sponge". Alcheringa: An Australasian Journal of Palaeontology. 7 (1): 49–58. Bibcode:1983Alch....7...49K. doi:10.1080/03115518308619633.
^ abBingli, L.; Rigby, J.; Zhongde, Z. (2003). "Middle Ordovician Lithistid Sponges from the Bachu-Kalpin Area, Xinjiang, Northwestern China". Journal of Paleontology. 77 (3). Paleontological Society: 430–441. doi:10.1666/0022-3360(2003)077<0430:MOLSFT>2.0.CO;2. JSTOR4094792.
^Keith Rigby, J. (1973). "A New Anthaspidellid Sponge from the Silurian of Lake Timiskaming, Quebec". Journal of Paleontology. 47 (4). Paleontological Society: 801–804. JSTOR1303055.
^Rigby, J.K.; Collins, D. (2004). Sponges of the Middle Cambrian Burgess Shale and Stephen Formations. Royal Ontario Museum Contributions in Science. Vol. 1. Royal Ontario Museum.