Mammalian Marine Animals

Sea cow (1) is a mammal—it's a marine mammal that breathes air and nurses its young. Sea lion (3) is a mammal—pinnipeds are marine mammals with flippers. Sea horse (2) is NOT a mammal—it's a fish (order Syngnathidae) that lays eggs and has gills. The key distinction is that mammals have lungs (not gills), nurse offspring, and are warm-blooded. Sea horses, despite their deceptive name, are fully aquatic fish. > Sea horse = fish (deceptive name); Sea cow & Sea lion = true marine mammals. Answer: (b).