Simple invertebrates are basic animals that have no backbone, including sponges, jellyfish, anemones, starfish, sea urchins, sand dollars, and a few different types of worms (yes, worms) that prefer the ocean over your lawn or garden. Wiggle over to Chapter 9 for more in simple invertebrates.

       Mollusks (covered in Chapter 10) are soft-bodied invertebrates, most of which have recognizable shells but some of which don’t. You may know them better as snails, slugs, clams, oysters, mussels, octopus, and squid. And some of these are colossal.

       Crustaceans (Chapter 11) are more advanced invertebrates with hard external skeletons, such as crabs, lobsters, shrimp, and krill. Just think “crusty,” like a good baguette: hard on the outside, soft on the inside.

       Fish (bony and not) comprise the first group of vertebrates (animals with a backbone or something like it). You usually know a fish when you see one — most have a head and tail, fins, gills, and scales. We break them down into two groups: cartilaginous (the real softies, as in soft-boned) such as sharks and rays, and bony (hard boned, that is) which includes just about everyone else, such as tuna, salmon, and cod. Swim over to Chapter 12 for more details.

       Reptiles (chillin’ in Chapter 13) are scaly, cold-blooded, air-breathing vertebrates that lay soft eggs on land or give birth to live young. The ocean is home to only a handful of reptiles, including sea turtles, marine iguanas, saltwater crocodiles, and a few species of sea snakes (the latter of which you really don’t want on your airplane).

       Birds are warm-blooded, air-breathing vertebrates with two legs, two wings, feathers, and a beak. Most fly, though some, such as the penguin, don’t. Most marine birds have special adaptations, such as the ability to secrete salt, oily wings to keep them from getting waterlogged, and webbed feet. Some have solid bones that enable them to dive more easily. Seabirds that dive-bomb their prey are even equipped with internal airbags to cushion their crash landings. In Chapter 14, we divide marine birds into two groups — seabirds, which spend most of their time on or flying over the ocean, and shorebirds, which spend most of their time on or near land or wading in the shallows of estuaries or marshes.

       Mammals (covered in Chapter 15) are warm-blooded vertebrates that have at least some hair or fur and must surface to breathe air. Females have mammary glands and give birth to live young. Marine mammals include everyone’s favorites — whales, dolphins, walruses, seals, sea otters, sea lions, manatees, dugongs, and polar bears.

       Achieving net-zero greenhouse gas emissions: Human-caused greenhouse gas emissions include dioxide, methane, ozone, nitrous oxide, and chlorofluorocarbons. Achieving net-zero greenhouse gas emissions by 2050, at a minimum, is critical to slowing and stopping human-caused climate change, ocean acidification, and warming ocean temperatures.

       Reduce pollution: Pollution in the air, water, and even on land ends up in the ocean. Sources of pollution include plastics (which never really biodegrade), sewage, industrial chemicals, agricultural fertilizers and pesticides, land runoff (especially from streets and parking lots), oil spills, ocean mining, littering, and the use of certain sunscreens.

       Fish sustainably: Overfishing combined with destructive fishing methods are devastating marine wildlife populations risk. International legislation and enforcement are crucial for ensuring a sufficient supply of seafood for ourselves as well as marine ecosystems.

       Create marine protected areas (MPAs): MPAs are areas where certain consumptive or destructive activities are prohibited for the purpose of protecting ecosystems, sustaining fisheries production, or preserving cultural resources.

       Engage youth: The best way to make lasting change is from the ground up. It starts by educating the youth. They’re best equipped to change their own behaviors and influence the minds, hearts, and actions of parents, teachers, government representatives, community members, and business leaders.