Hederellida

Article By:

Ross, June R. P. Department of Biology, Western Washington University, Bellingham, Washington.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.757414

A marine bryozoan order in the class Stenolaemata. It is recorded from scattered localities in the Ordovician through Permian systems of the Paleozoic Era but is found prominently in Devonian strata. The colonies comprise tubular zooecia that commonly encrust brachiopod shells, echinoderm plates and columnals, and the outer surfaces of corals. Although usually encrusting, the colonies sometimes may be erect structures. The initial zooecium is a bulbous ancestrula, which gives rise to a tubular zooecium. Succeeding tubular zooecia bud, one at a time, from the lateral wall of the preceding zooecium. The tubular zooecia have perforated walls, and the distal opening of the zooecium is commonly sealed by a plate (possibly perforate). The zooecial wall apparently consisted of two layers, but it lacks the distinctive laminate structures of the order Trepostomata (Stenolaemata) and shows no additional thickening in the outer parts of the colony.

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