Oceans For Dummies. Joseph Kraynak

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       Viruses are infectious agents that invade cells and use them to replicate. They’re not even classified as living beings (burn!).

       Bacteria are single-celled organisms that have a cell wall but no nucleus (a container for most of the cell’s genetic material) or organelles (specialized structures in a cell that perform various functions).

       Protists are single-celled organisms equipped with a nucleus and organelles. They’re not animals, plants, or fungi, but some are similar to plants in that they perform photosynthesis, some are similar to animals in that they move around and eat stuff, and some are more of a cross between the two — moving around, eating stuff, and performing photosynthesis.

       Fungi are single-celled or multicelled organisms that feed on organic matter. They include yeasts, molds, mushrooms, and toadstools.

       Phytoplankton are single-celled photosynthetic organisms sometimes described as “floating plants.” Most are single-cell algae (micro-algae), but phytoplankton also include a type of photosynthetic bacteria called cyanobacteria.

       Macro-algae are several species of macroscopic, multicellular marine algae commonly referred to as “seaweed.” They look like plants and can be very large, but they have no vascular system for distributing nutrients. All the cells that make up the seaweed absorb liquids and nutrients from the surrounding water.

       Seagrass is a plant, complete with a vascular system, leaves, roots, and rhizomes (just like lawn grass); they’re pollinated under water, and they produce seeds.

       Mangroves are highly salt-tolerant trees and shrubs that grow along shorelines in tropical locations. In addition to providing food, shelter, and breeding areas for other marine organisms, mangroves play an important role in protecting and even building land.

       Zooxanthellae: Pronounced zo-uh-zan-thel-ee, these are single-celled photosynthetic organisms that live inside the cells of many marine animals, including coral polyps and some jellyfish, nudibranchs (sea slugs), and sponges, providing them with food in exchange for a place to live.

       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.