Upwelling
The major upwellings in the ocean are associated with the divergence of currents that bring deeper, colder, nutrient rich waters to the surface. There are at least five types of upwelling: coastal upwelling, large-scale wind-driven upwelling in the ocean interior, upwelling associated with eddies, topographically-associated upwelling, and broad-diffusive upwelling in the ocean interior.
Hemibdella soleae
"H. soleae" is an ectoparasite of flatfish such as the common sole ("Solea solea"). Like other marine leeches, it feeds on its host's blood, but unlike most freshwater species, it does not drop off the fish after it has fed, instead remaining attached by its anterior sucker. In the juvenile leech, the remnants of each blood meal is visible through the transparent skin as a small red ball inside. In the northern part of its range, the common sole is the main host, but further south, other fish are also parasitized; these include the Senegalese sole ("Solea senegalensis"), the wedge sole ("Dicologlossa cuneata"), the bastard sole ("Microchirus azevia"), the Klein's sole ("Synapturichthys kleinii"), the sand sole ("Pegusa lascaris") and the Portuguese sole ("Dagetichthys lusitanica"). In the English Channel, small common sole may have one or two leeches on them while large fish may have forty or more of the parasites.