Branching pattern and morphogenesis of medusa tentacles in the jellyfish Cladonema pacificum (Hydrozoa, Cnidaria)

The Cladonema pacificum jellyfish. a Life cycle of C. pacificum. An individual polyp generated through metamorphosis of the planula larva extends a stolon and produces genetically identical populations of polyps along the extended connection. Polyps are full of nutrients and form medusa buds on the side of their bodies, and they are eventually released and grow into mature female and male organisms. Eggs and sperm spawned by light stimuli are fertilized, and the fertilized eggs develop into planula larvae. The cycle shown by blue arrowheads indicates an artificial method commonly used in the laboratory to increase the efficiency of medusa formation. In this method, polyps are kept at 4？°C for at least three months resulting in polyp degeneration, and then they again transferred back at 21？°C to induce the formation of new polyps. b An adult C. pacificum. The medusa tentacles of this species are branched into two different types with either nematocyst clusters along their length for hunting (arrowhead) or adhesive organs on their tips for landing (arrow). Scale bar: 1？m