| A | B |
|---|
| Adaptation | a part or behavior that makes a living thing better able to survive in its environment |
| Amphibian | a vertebrate that usually lives in water in the early part of its life: it breathes with gills and then later develops lungs |
| Arthropod | invertebrate animals, including the insects, crustaceans, and arachnids that have an exoskeleton and a segmented body to which jointed appendages are attached in pairs |
| Arachnids | Invertebrates such as such as spiders, scorpions, mites, and ticks that have four pairs of segmented legs and a body that is divided into two regions |
| Behavior | the way in which a living thing acts or responds to its environment |
| Bird | a vertebrate that has wings, is covered with feathers, and hatches from a hard-shelled egg |
| Carnivore | a consumer that eats only other animals |
| Cephalopods | marine mollusks, such as the octopus, squid, cuttlefish, or nautilus that have a large head, large eyes, tentacles, and, in most species, an ink sac containing a dark fluid used for protection or defense |
| Consumer | a living thing that obtains energy by eating other living things |
| Crustaceans | predominantly aquatic invertebrates such as lobsters, crabs, shrimps, and barnacles that have a segmented body, an exoskeleton, and paired, jointed limbs |
| Decomposer | a living thing that breaks down the remains of dead organisms |
| Echinoderms | symmetrical marine invertebrates, such as starfishes, sea urchins, and sea cucumbers that are often covered with spines |
| Endangered | in danger of becoming extinct |
| Exoskeleton | a hard outer structure, such as a shell that protects, or supports an animal’s body |
| Extinct | no longer living as species |
| Fish | a vertebrate that lives in water and has gills for breathing and fins for swimming |
| Food web | the overlapping food chains that link producers, consumers, and decomposers in an ecosystem |
| Gill | a feathery structure on each side of a fish’s head that lets the fish breathe underwater |
| Herbivore | a consumer that eats only plants |
| Insects | usually small arthropod invertebrate that have an adult stage characterized by three pairs of legs and a body segmented into head, thorax, and abdomen and usually having two pairs of wings |
| Instinctive behavior | a behavior that a living thing does naturally without having to learn it |
| Invertebrate | an animal that does not have a backbone |
| Learned behavior | a behavior that an organism is taught or learns from experience |
| Mammal | a vertebrate, such as a cat that has hair or fur and that feeds it young with milk |
| Mollusks | chiefly marine invertebrates that have a soft body and a mantle and/or a shell |
| Omnivore | a consumer that eats both plants and animals |
| Organism | a living thing that can be classified as belonging to one of five kingdoms |
| Population | a group of the same kind of organisms that live in an area |
| Producer | an organism that makes its own food through the process of photosynthesis |
| Reptile | a vertebrate, such as a lizard, that has dry scaly skin and lays eggs that have a leathery shell |
| Sponges | marine invertebrates, also known as Porifera, having a porous body and often found in irregularly shaped colonies attached to an underwater surface |
| Vertebrate | an animal that has a backbone |
| Worms | invertebrates that have a long, flexible, rounded, segmented, or flattened body without appendages |
