Mother and juvenile bottlenose dolphins head to the seafloor. Sea lion rises to bark at a research vessel. Catalina Island off southern CA, former home of a NURP center. Close up of worm tubes, sometimes the most prominent structures on sandy bottom. Gulf of Mexico, Mississippi River mouth 115.
Bacterial mats are common the seafloor where oxygen is low.
Mangroves of South Florida are threatened coastal development. Mangroves roots serve as critical habitat for many species and nutrient filters. Gravel-cobble bottom off Maine coast is favored scallop ground. Penguins explore snow-dunes in Antarctica 120. Sponges are as important as corals for reef structure.