Introduction Oceans and seas cover over 70% of the world's surface, and include some of the most productive environments on the planet (Michaelis & Carocci, 2000). There are an estimated 300,000 know marine species and they represent more phyla than in terrestrial environments. Life is unevenly distributed with areas of the deep oceans relatively void of life compared to coastal regions. Species diversity is higher in coastal rather than oceanic regions, and higher in tropical regions than …showed first 75 words of 1739 total…

…showed last 75 words of 1739 total…www.andrewgray.com/essays/molluscs.htm Michaelis, F.B. & Carocci, F. (2000). Coastal and Marine Habitats. http://www.oceansatlas.org/servlet/CDSServlet?status=ND0yMzg0JmN0bl9pbmZvX3ZpZXdfc2l6ZT1jdG5faW5mb192aWV3X2Z1bGwmNj1lbiYzMz0qJjM3PWtvcw~~ Restrepo, C.E. (2003). Octopuses, Squids, Cuttlefishes, and Nautiluses: The Fascinating World of Cephalopods. http://www.geocities.com/darthdusan/cephalopods.html Thinkquest Team, (1998). Adaptations of the Respiratory System. http://library.thinkquest.org/17963/respiratory-system.html