hydrocaulus
Hydrocaulus is a term used in cnidarian biology, specifically in colonial hydroids of the class Hydrozoa, to denote the main axis or stalk of a colony. The hydrocaulus is typically a hollow, tubular structure formed of a chitinous or sclerotized tube that serves as the framework for bearing feeding units. Along this axis, feeding polyps (hydranths) are housed in protective cups called hydrothecae, each opening to the surrounding water and bearing tentacles for prey capture.
Reproductive and colonial organization varies among species. In many hydroids, gonophores or other reproductive zooids develop
Origin and development: During colony growth, the hydrocaulus arises from stolon-like tissue that anchors the colony
Taxonomic and ecological context: The hydrocaulus is a characteristic feature of many thecate hydroids, a subset
Etymology: From Greek hydor (water) and caulus (stem or stalk).