• Relate the structural and behavioral adaptations of arthropods to their ability to live in different habitats.

Section Objectives: 28.1

• Analyze the adaptations that make arthropods an evolutionarily successful phylum.

• A typical _______ is a segmented, _______ invertebrate animal with________ symmetry, an exoskeleton, and jointed structures called appendages.

• An _______ is any structure, such as a leg or an antenna, that grows out of the body of an animal.

• Arthropods are the earliest known _________ to exhibit jointed appendages.

• Joints are advantageous because they allow more flexibility in animals that have hard, rigid __________.

• Joints also allow powerful movements of appendages, and enable an appendage to be used in many different ways.

• The exoskeleton is a hard, thick, outer covering made of ______ and ____ (KI tun).

• In other species, the exoskeleton is made of separate ______ held together by hinges.

• In some species, the exoskeleton is a continuous covering over most of the body.

• In many aquatic species, the exoskeletons are reinforced with ________ ____.

• The exoskeleton protects and supports internal tissues and provides places for attachment of _______.

• First, they are relatively _____ structures. The larger an arthropod is, the ______ and heavier its exoskeleton must be to support its larger muscles.

• _________ have their disadvantages.

• A second and more important disadvantage is that exoskeletons cannot _____, so they must be ___ periodically. Shedding the old exoskeleton is called _______.

• When the new ________ is ready, the animal contracts muscles and takes in air or water.

• This causes the animal’s body to swell until the old exoskeleton splits open, usually along the back.

• Thus, the new exoskeleton hardens in a ________ size, allowing some room for the animal to continue to grow.

• Before the new exoskeleton hardens, the animal puffs up as a result of increased _______ circulation to all parts of its body.

• When the new exoskeleton is soft, arthropods cannot _____ themselves from danger because they move by bracing muscles against the _____ exoskeleton.

• Most arthropods ____ four to seven times in their lives before they become adults.

• In most groups of arthropods, segments have become fused into three body sections—_____, _____, and ______.

• In other groups, even these segments may be fused.

• Some __________ have a head and a fused thorax and abdomen.

• In other groups, there is an abdomen and a fused head and thorax called a ________________.

• Fusion of the body segments is related to movement and protection.

• This large oxygen demand is needed to sustain the high levels of ________ required for rapid movements.

• ________ have efficient respiratory structures that ensure rapid oxygen delivery to cells.

• Three types of respiratory structures have evolved in arthropods: ____, ___ tubes, and ____ lungs.

• _____ arthropods exchange gases through _____, which extract oxygen from water and release carbon dioxide into the water.

• Land arthropods have either a system of ______ tubes or _____ lungs.

• Most insects have _______ tubes, branching networks of hollow air passages that carry air throughout the body.

• Air enters and leaves the tracheal tubes through openings on the thorax and abdomen called _______.

• Muscle activity helps pump the air through the ______ tubes.

• Most _____ and their relatives have book lungs, air-filled chambers that contain leaflike plates.

• The stacked plates of a ____ lung are arranged like pages of a book.

• Movement, sound, and chemicals can be detected with great sensitivity by ______, stalk-like structures that detect changes in the environment.

• Antennae are also used for ____ and ____ communication among animals.

• The ants were able to work together as a group because they were communicating with each other by ______, chemical odor signals given off by animals.

• Have you ever watched as a group of ants carried home a small piece of food?

• Accurate vision is also important to the active lives of arthropods.

• Most arthropods have one pair of large _________eyes and three to eight ______ eyes.

• A simple eye is a visual structure with only one ____ that is used for detecting light.

• _________ sense the odors of pheromones.

• A ________ eye is a visual structure with many lenses.

• Each lens registers light from a tiny portion of the field of view.

• The total image that is formed is made up of thousands of parts.

• The nervous system consists of a double _______ nerve cord, an _____ brain, and several ______.

• Arthropods have ganglia that have become fused. These ganglia act as control centers for the body section in which they are located.

• Arthropod blood is pumped by a heart in an _____ circulatory system with vessels that carry blood away from the heart.

• The blood flows out of the ______, bathes the tissues of the body, and returns to the heart through open body spaces.

• Arthropods have a complete _______ system with a mouth, stomach, intestine, and anus, together with various glands that produce digestive ________.

• The mouthparts of most arthropod groups include one pair of jaws called ___________.

• The mandibles, together with other mouthparts are adapted for holding, chewing, sucking, or biting the various foods eaten by arthropods.

• Most ______ arthropods excrete wastes through _______ tubules.

• In insects, the tubules are all located in the _______ rather than in each segment.

• Malpighian tubules are attached to and empty into the _______.

• Another well-developed system in arthropods is the ______ system.

• In an arthropod limb, the muscles are attached to the inner surface of the ___________.

• An arthropod muscle is attached to the exoskeleton on both sides of the joint.

• Most arthropod species have separate males and females and reproduce _______.

• Fertilization is usually _______ in land species but is often _______ in aquatic species.

• Some species, including bees, ants, aphids, and wasps, exhibit ______________, a form of asexual reproduction in which a new individual develops from an unfertilized egg.

• Compare and contrast the similarities and differences among the major groups of arthropods.

Section Objectives: 28.2

• Explain the adaptations of insects that contribute to their success.

• ___ and ____ differ from spiders in that they have only one body section.

tick

• The head, thorax, and abdomen are completely fused.

• Ticks feed on ____ from reptiles, birds, and mammals.

• ___ feed on fungi, plants, and animals.

• They are so small that they often are not visible to the unaided human eye.

• Like ticks, mites can transmit ______.

• _______ are easily recognized by their many abdominal body segments and enlarged ________.

• They have a long tail with a _______ stinger at the tip.

• ______ (krus TAY shuns) are the only arthropods that have two pairs of antennae for sensing.

• All crustaceans have ________ for crushing food and typically have two compound eyes.

• Unlike the up-and-down movement of your jaws, crustacean mandibles open and close from ____ to _____.

• Many crustaceans have ____ pairs of walking legs.

• The first pair of walking legs are often modified into strong ______ for defense.

claw legs

• Members of the class _______ include crabs, lobsters, shrimps, crayfishes, water fleas, pill bugs, and barnacles.

• Most crustaceans are _____ and exchange gases as water flows over feathery ____.

• __ bugs and ___bugs, two of the few land crustaceans, must live where there is _______, which aids in gas exchange.

• Like spiders, ______ and ______ have Malpighian tubules for excreting wastes.

• In contrast to spiders, centipedes and millipedes have _______ tubes rather than book lungs for gas exchange.

• Centipedes are ___________ and eat soil arthropods, snails, slugs, and worms

• The ____ of some centipedes are painful to humans.

• A millipede eats mostly plants and dead material on damp forest floors.

• _______ do not bite, but they can spray foul-smelling fluids from their defensive _____ glands.

• __________ crabs are members of the class __________.

• Horshoe crabs are considered to be living fossils; Limulus fossils have remained relatively unchanged since the ______ Period about 220 million years ago.

• Horseshoe crabs are heavily protected by an extensive __________ and live in deep coastal waters.

• They forage on sandy or muddy ocean bottoms for algae, _______, and mollusks.

• Flies, grasshoppers, lice, butterflies, bees, and beetles are just a few members of the class _______.

• Insects have ____ body segments and ___ legs.

• There are more ______ of insects than all other classes of animals combined.

• Insects usually mate _____ during their lifetime.

• The eggs usually are ______ internally.

• Some insects exhibit ___________, reproducing from unfertilized eggs.

• Most insects lay a ____ number of eggs, which increase the chances that some offspring will survive long enough to reproduce.

• After eggs are laid, the insect _______ develops and the eggs hatch.

• In some _______ insects development is direct; the eggs hatch into miniature forms that look just like tiny adults.

• These insects go through successive ___ until the adult size is reached.

EggsNymph

Molt

Nymph

Molt

Adult

• In some cases, the adult insect bears little resemblance to its ________ stage.

AdultEgg

LarvaPupa

• Insects that undergo metamorphosis usually go through four stages on their way to adulthood: ___, _____, ____, and ______.

• This series of changes, controlled by chemical-substances in the animal, is called _______________.

• Other insects that undergo complete metamorphosis include ants, beetles, flies, and wasps.

• Many insect species, as well as other arthropods, undergo a gradual or incomplete metamorphosis, in which the insect goes through only _____ stages of development.

• These three stages are ___, ______, and adult.

• A _____, which hatches from an egg, has the same general appearance as the adult but is smaller.

EggsNymph

Molt

Nymph

Molt

Adult

• ________ cannot reproduce.

• As the nymph eats and grows, it molts several times. With each _____, it begins to resemble the adult more.

• Gradually, the nymph becomes an adult.

• Grasshoppers and cockroaches are insects that undergo ________ metamorphosis.

Incomplete metamorphosis of a harlequin bug

• The success of arthropods can be attributed in part to their varied life cycles, high reproductive output, and structural adaptations, such as small size, a hard exoskeleton, and jointed appendages.

• Arthropods most likely evolved from an ancestor of the _______.

• Segments in arthropods are more complex than in annelids, and arthropods have more developed _____ tissue and sensory organs, such as eyes.

• The exoskeleton of arthropods provides _______ for their soft bodies.

• Muscles in arthropods are arranged in _____ associated with particular segments and portions of appendages.

• The circular muscles of _______ do not exist in arthropods.

• Because arthropods have many hard parts, much is known about their evolutionary history.