Subject: A colony of Zoanthids (the order is also called Zoanthidae, Zoantharia or Zoanthiniaria). Zoanthids are anemone-like animals. These Cnidarians rely partially on photosynthesis to provide them with nutrition. However, photosynthesis alone does not deliver enough nutrients to keep them alive so they also need to capture plankton with their marginal tentacles. Some species of Zoanthids contain a deadly poison called “palytoxin”.
Technique: This clip was filmed on a night dive. In the darkness your video lights are magnets for all kinds of planktonic life. When your lights are posed too close to your subject these swarms of little critters can be a real nuisance and interfere with the quality of your recordings, therefor on night dives, you should place your lights as far away from your subject as possible.