Steven McPherson, 2012-2013, Wavelengths (detail): Unaltered Marine Plastic Debris objects found on the UK coast, 1994-2013. Pollution affecting marine life within the Pelagic Zone consists primarily of plastic debris in both shallow and deep waters. "This work has been split into 5 segments that denote the main oceans, and the distribution and colours of the plastic debris describe the size and depth of each of the pelagic zones of these oceans." Caption at link
Sea angels are a funny name for a sea slug, but in this case it's right on point. They dwell in the pelagic zone, so in the middle layer of the ocean, and is an opisthobranch, meaning its gills are behind it and help propel it through water. These gastropods have relinquished their shells and grown a free-moving tail-like appendage, both of which assist it in autonomous motion.