29.1 An Overview of Arthropods
| Arthropod - segmented invertebrate with jointed appendages and exoskeleton. |
| Exoskeleton - composed of protein bound to chitin. |
| During molting, arthropod is vulnerable to injury and predators. |
| Peripatus does not have hard exoskeleton or jointed appendages. |
| Millipedes have two pairs of legs on each body segment and don't have poisonous fangs. |
29.2 Crustaceans
| The only crustaceans tha live in terrestrial areas are pill bugs and few species of crabs. |
| Cephalothorax - fused head and chest region to which legs and other appendages are attached. |
| Mandibles - one pair of jawlike appendages that chew and crush food. |
| Gill bailers - pair of appendages that beat back and forth to move water across gills when crayfish isn't moving. |
| Green gland - it retains salt and removes excess water. |
| Copepods, main component of plankton, is a food source for many fish. |
| Isopods are well adapted to live on land. |
| They live in moist, dark areas where they eat dead organisms. |
29.3 Arachnids
| Pedipalps - second pair of mouthparts that help hold and chew food. |
| Book lungs - modified gills that hang down like the pages in a book. |
| Malpighian tubules - excretory organs that filter wastes from body fluids. |
| Spiders that weave webs to catch prey have long, slender legs and relatively poor eyesight. |
| Horseshoe crabs are neither crabs or arachnids, but are called chelicerates. |
29.4 Insects
| Sensing male moths can find a female by sensing pheromones. |
| Metamorphosis - series of changes during which young insects change into adults. |
| Pupal stage - once larva reaches certain size and finds a sheltered place it forms a protective case around itself. |
| Praying mantis resembles a twing in the environment. |
29.5 The Importance of Arthropods
| Krill - tiny shrimplike crustaceans that are sole diet of whales. |
| Native flowers would not have survived without the benefit of the honeybee. |
| Some plants and insects have coevolved where they need each other. |
| Examples are the yucca moth and yucca plant. |
| People raise silkworms to spin fine silken threads to make silk fabric. |