Term: caudal fin actinotrichium
Name: caudal fin
Synonyms: tail, tail fin
Definition: Fin that is the most posterior median fin. It is composed of a complex of three modified centra and modified neural and hemal arches and spines.
Ontology: Anatomy Ontology [ZFA:0001058]

Name: actinotrichium
Synonyms: actinotrichia
Definition: Skeletal element which is a slender, horny, flexible, unsegmented fibril which provide structural support to fin folds or fins. Actinotrichia are translucent, exhibit birefringence (double refraction) and are composed of the scleroprotein elastoidine.
Ontology: Anatomy Ontology [ZFA:0005435]