Solanderia

Solanderia is the sole genus of hydrozoans in the monotypic family Solanderiidae. They are commonly known as tree hydroids or sea fan hydroids.

==Description== left|thumb|300x300px|Solanderia sp. at Rakitu Island (Arid Island), Great Barrier Island, New Zealand Solanderia hydroids forms large colonies. They are one of about 1000 species of athecate hydroids, which do not construct a skeletal covering for their polyps (as opposed to the thecate hydroids in the order Leptothecata. The chitinous skeleton is internal, branches, and may form anastomoses. The skeleton is formed by coalescence and modification of adjacent hydrocauline tubes. The coenosarc covers the entire colony and penetrates skeletal interstices. The hydranths cover the whole colony surface and are uniform in structure, cylindrical, with a single whorl of capitate tentacles around the mouth. Numerous similar tentacles are scattered over the body. Solanderia is known from its polyp or hydroid stage, and produces gonophores which release sperm and eggs for reproduction. Where known, the gonophores are cryptomedusoid or eumedusoid, arising directly from the coenosarc.