•what seven characteristics are unique only to marine mammals—not all mammals?
•what two suborders do we classify order carnivora into?

PART 1

1. They nurse their young with milk produced by mammary glands.
2. There are international laws and treaties that protect marine mammals.
3. Unfortunately, many marine mammals are considered endangered species and there are still threats to most of their populations, such as illegal hunting, pollution, climate change, and habitat loss. 
4. They have adapted to living all or part of their life in the ocean.
5. To keep warm in the ocean, most of them depend on a thick layer of blubber (or fat). 
6. To be able to stay under water for long periods, they store extra oxygen in their muscles and blood.
7. They also have more blood than land mammals in proportion to their body sizes, can direct their blood flow to only their vital organs (such as their heart and lungs), and can slow their heartbeat down so they are using less oxygen in a dive.

PART 2
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea                                                                                                                                                                                              The Order Cetacea is the group of marine mammals that includes the cetaceans - the whales, dolphins andporpoises.There are 86 species of cetaceans, and these are divided into two suborders - the mysticetes (baleen whales, 14 species) and odontocetes (toothed whales, 72 species).

Hope this helped...Good luck!