Biology/Natural History: This hydroid retains the medusae within the corbulae. Corbulae containing male and female gonophores look slightly different. The medusae, which are highly modified, release eggs and sperm (the eggs are retained in the female medusae until fertilization, and it is the planula that is released). The planula larva settles to the bottom, crawls for awhile, and grows into a new hydroid. Caprellid "skeleton shrimp" and pycnogonids can often be found climbing on hydroids such as this species.