They are the biggest ray. Mantid Also called the praying mantid or praying mantis, this predatory insect eats garden pests. Marbled Murrelet A small seabird from the Pacific Northwest of North America. Marine Mammals Mammals that spend most of their lives in the seas. Marsupials Marsupials are mammals whose young are born very immature.
Most female marsupials have pouches.
Massospondylus An early plant-eating dinosaur with a long neck and long tail. The Mastiff is a huge, intelligent, and powerful dog that is often used as a guard dog. Mastodon Mastodons were shaggy, tusked herbivores. Meadowlark, Western A brightly-colored songbird from western and central North America. Megalodon A huge, extinct shark.