For mammals, originally designed for life on land, the marine environment is harsh and demands significant evolutionary changes to be habitable. Keeping warm, moving, seeing and birthing all present challenges and demand creative solutions.
On top of all the basic difficulties of a marine environment, habitats dominated by water are not uniform. Within each region of the world, there are differences, large and small, in temperature, chemistry and productivity. All of these factors can vary daily, yearly, or over millennia. That we have marine mammals at all is nothing short of amazing.
Mammals have, despite these challenges, successfully adapted to life at sea. Today, over 100 species of mammals can be found in marine environments, from rivers to coastlines, mangroves to oceans. This astonishing diversity is a reflection of the wide range of habitats and the many methods of adaptation marine mammals have discovered.
Marine mammals range from 50 pound sea otters to 100 ton blue whales. Some, like the manatee, are herbivores, grazing their way through the water. Others, like right whales, eat plankton. Some marine mammals, like bottlenose whales, may never see a coastline in their lives, while animals like seals always are near something solid, be it ice floe or beach.
Considering the richness of Stellwagen Bank, it is not surprising that an array of marine mammals is found here. Each species affects and is affected by this habitat in a unique way. Representatives from two large groups, pinnipeds (seals) and cetaceans (whales), make use of the Bank at some point during the course of the year.