Rhizocaulus verticillatus -... www.habitas.org.uk

WoRMS - World Register of... www.marinespecies.org

Rhizocaulus verticillatus www.britishmarinelifepictur...

Invert-E-Base Portal -... www.invertebase.org

Invert-E-Base Portal -... www.invertebase.org

Horse-Tail Hydroid... naturediver.com

Photos of horsetail hydroid... www.inaturalist.org

BOLD Systems: Taxonomy... v3.boldsystems.org

Invert-E-Base Portal -... www.invertebase.org

BOLD Systems: Taxonomy... v3.boldsystems.org

Invert-E-Base Portal -... www.invertebase.org

Rhizocaulus verticillatus www.britishmarinelifepictur...

New species or population... marinemastersum.w.uib.no

BOLD Systems: Taxonomy... v3.boldsystems.org

COPEPEDIA summary for... apps-st.fisheries.noaa.gov

Rhizocaulus verticillatus www.britishmarinelifepictur...

BOLD Systems: Taxonomy... v3.boldsystems.org

COPEPEDIA summary for... www.st.nmfs.noaa.gov

distMAP_T4000801_50.jpg www.st.nmfs.noaa.gov

Rör hi-res stock... www.alamy.com