Gonotheca

Gonotheca is a term used in zoology, specifically in the study of colonial hydroids. It refers to the protective sheath or casing that encloses the reproductive polyp, known as a gonozooid, within a hydroid colony. Hydroid colonies are complex structures composed of many individual zooids, each specialized for a particular function such as feeding, defense, or reproduction. The gonotheca serves to house and protect the developing reproductive structures, which can include either male or female gametes.

The morphology of gonothecae can vary considerably among different hydroid species. They may be simple, tubular structures, or they may be more elaborate, sometimes bearing spines or other ornamentation. The shape and arrangement of gonothecae can be important characteristics for identifying and classifying hydroid species. Inside the gonotheca, the gonozooid matures and produces either sperm or eggs. After fertilization, the resulting planula larva develops within the gonotheca or is released into the water. The presence and development of gonothecae are indicators of the reproductive stage of a hydroid colony.