Siphonophores are holoplanktonic and include the Portuguese Man of War. Physophora feeds upon phytoplankton and smaller zooplankton, such as herbivorous copepods. Colonies are up to 50 mm high. 60 mm high. It preys on copepods and other small crustaceans.
Ctenophores lack the nematocysts characteristic of jellyfish.
Unidentified Ctenophore Photo by MarshYoungbluth Ctenophore Photo by Marsh Youngbluth Ctenophores are ubiquitous in the ocean and their systematics are poorly understood. They are efficient suspension feeders, feeding on smaller zooplankton, fish eggs, and planktonic larvae. This undescribed ctenophore has remarkable coloration. Ctenophores are commonly multi-colored, owing to refraction along meridional rows of fused cilia known as comb rows. The herbivorous copepod Eurytemora affinis is common in estuarine waters all over the northern hemisphere.