1. Chapter 23 Animals I: Major Invertebrate Groups (Sections 23. 11 - 23

2. 23.11 Spiders and Their Relatives
Chelicerates include horseshoe crabs and arachnids
They are predators, parasites, or scavengers
chelicerates
Arthropod subgroup with specialized feeding structures (chelicerae) and no antennae
arachnids
Land-dwelling arthropods with four pairs of walking legs; spiders, scorpions, mites, and ticks

3. Tarantula, a Spider
Chelicerates have a body with a cephalothorax (fused head and thorax) and abdomen
Pedipalps, lie between the chelicerae and the first legs

4. Tarantula, a Spider abdomen cephalothorax pedipalps
Figure Examples of chelicerates. A Tarantula, a spider. B Horseshoe crab (Limulus). The long spine helps it steer as it swims. C Scorpion. Its last segment has a stinger and the pedipalps are claws that can seize prey. D A blood-engorged tick. E Dust mite, less than 0.5 millimeter in length.
pedipalps
four of eight walking legs
Fig a, p. 368

5. Horseshoe Crab
Horseshoe crabs are an ancient chelicerate lineage and the only one that is marine
Figure Examples of chelicerates. A Tarantula, a spider. B Horseshoe crab (Limulus). The long spine helps it steer as it swims. C Scorpion. Its last segment has a stinger and the pedipalps are claws that can seize prey. D A blood-engorged tick. E Dust mite, less than 0.5 millimeter in length.

6. Scorpions
Scorpions dispense venom through a stinger on their telson; their pedipalps evolved into large claws
Figure Examples of chelicerates. A Tarantula, a spider. B Horseshoe crab (Limulus). The long spine helps it steer as it swims. C Scorpion. Its last segment has a stinger and the pedipalps are claws that can seize prey. D A blood-engorged tick. E Dust mite, less than 0.5 millimeter in length.

7. Ticks and Mites All ticks are parasites
Mites include parasites, predators, scavengers
Figure Examples of chelicerates. A Tarantula, a spider. B Horseshoe crab (Limulus). The long spine helps it steer as it swims. C Scorpion. Its last segment has a stinger and the pedipalps are claws that can seize prey. D A blood-engorged tick. E Dust mite, less than 0.5 millimeter in length.

8. 23.12 Crustaceans
Small crustaceans reach great numbers in the seas and are an important food source for larger animals
Marine crustaceans include crabs, lobsters, barnacles, krill, and copepods
crustaceans
Mostly marine arthropod group with two pairs of antennae

9. Crustacean Diversity
Figure Examples of crustaceans. A Antarctic krill no more than 6 centimeters long. B Free-living female copepod from the Great Lakes, about 1 millimeter long. Note the eggs. C Goose barnacles capturing food with their jointed legs.

10. Decapod Crustaceans
Lobsters, crayfish, crabs, and shrimps all belong to the same crustacean subgroup (decapods)
All are bottom feeders with five pairs of walking legs – the first pair are often modified as claws
Like all arthropods, they molt as they grow

11. Lobster Body Plan

12. Lobster Body Plan abdomen segments cephalothorax (fused segments)
eyes (two)
antennae (two pairs)
food-handling appendages
(three pairs)
Figure Body plan of a clawed lobster (Homarus americanus).
tail fan
swimmerets
first leg
walking legs (five pairs)
Fig , p. 369

13. Crab Life Cycle

14. Crab Life Cycle egg adult female juvenile larva
Figure Crab life cycle. Larval and juvenile stages molt repeatedly and grow in size before they are mature adults.
larva
Fig , p. 369

15. ANIMATION: Crab life cycle
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16. 23.13 Insect Traits and Diversity
Insects are the most diverse arthropods, and include the only winged invertebrates
insects
Most diverse arthropod group
Members have six legs, two antennae and, in some groups, wings

17. Characteristic Features
Insects have a three-part body plan, with a head, thorax, and abdomen
Insects are mostly terrestrial; tracheal tubes carry air from surface openings to tissues deep inside the body
Some insects undergo metamorphosis in which tissues of a juvenile are reorganized
Some insects undergo incomplete metamorphosis, in which nymphs change a little with each molt

18. Basic Insect Body Plan
Structures of a bedbug head, thorax, and abdomen

19. Basic Insect Body Plan abdomen thorax with six legs
Figure A bedbug illustrates the basic insect body plan: a head, thorax, and abdomen. The bug is 7 millimeters long.
thorax with six legs
head with two eyes, and two antennae
Fig , p. 370

20. Metamorphosis

21. Metamorphosis A Incomplete metamorphosis egg nymphs adult
Figure Insect development. A Incomplete metamorphosis of a bug. Small changes occur with each molt. B Complete metamorphosis of a fruit fly. A larva develops into a pupa that undergoes a dramatic remodeling into the adult form.
egg
nymphs
adult
Fig a, p. 370

22. Metamorphosis B Complete metamorphosis egg larvae pupa adult
Figure Insect development. A Incomplete metamorphosis of a bug. Small changes occur with each molt. B Complete metamorphosis of a fruit fly. A larva develops into a pupa that undergoes a dramatic remodeling into the adult form.
egg
larvae
pupa
adult
Fig b, p. 370

23. Diversity and Abundance
The four most successful insect lineages all have wings and undergo complete metamorphosis:
Flies: ~150,00 species
Beetles: ~ 150,000 species
Hymenopterans (wasps, bees, ants): ~ 130,000 species
Moths and butterflies: ~ 120,000 species

24. Insect Diversity

25. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig a, p. 371

26. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig b, p. 371

27. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig c, p. 371

28. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig d, p. 371

29. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig e, p. 371

30. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig f, p. 371

31. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig g, p. 371

32. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig h, p. 371

33. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig i, p. 371

34. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig j, p. 371

35. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig k, p. 371

36. Insect Diversity Figure 23.32 A sampling of insect diversity.
A Silverfish, an ancient lineage that does not undergo metamorphosis. Insects that undergo incomplete metamorphosis: B European earwig, a common household pest. C Duck louse. It eats bits of feathers and skin. D Cicada. Male cicadas are among the loudest of all insects. E Damselfly, one of the insects that has aquatic larvae. F Termites. These sterile soldiers can shoot a gluelike substance from their head to protect their colony. G Grasshopper. Members of the four most diverse insect orders. All are winged and undergo complete metamorphosis: H A fly, dusted with pollen. I Ladybird beetles with a distinctive red and black spotted wing cover. J Staghorn beetle from New Guinea. K Bald-faced hornet, a type of wasp. This is a fertile female, or queen. She lives in a papery nest with her many offspring. L Swallowtail butterfly, a lovely lepidopteran, shown acting as pollinator.
Fig l, p. 371

37. ANIMATION: Insect Development
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38. 23.14 The Importance of Insects
It would be hard to overestimate the importance of insects, for either good or ill
Some perform ecological services as decomposers and pollinators; others harm crops and transmit diseases

39. Ecological Services
Most flowering plants are pollinated by members of the four most successful insect groups
Insects serve as food for a variety of wildlife (birds, fish, amphibians, reptiles, and even humans)
Insects dispose of wastes (feces) and remains (animal corpses)

40. Cleanup Crew A dung beetle gathers a ball of dung (feces)
The beetle will lay its eggs in the dung and the larval beetles will feed on it as they grow
Figure Cleanup crew. A dung beetle gathers a ball of dung (feces). The beetle will lay its eggs in the dung and the larval beetles will feed on it as they grow.

41. Competitors for Crops
Insects devour 1/4 to 1/3 of all crops grown in the United States
Mediterranean fruit fly (Med fly) lays eggs in fruits and vegetables
Figure Mediterranean fruit fly (Med fly), a major threat to fruit crops.

42. Vectors for Disease
Mosquito-borne diseases such as malaria kill more than 1 million people each year
Other disease vectors include flies, fleas, ticks and lice
The deadliest animal
Figure The deadliest animal. When it comes to bites, no animal is more dangerous than the mosquito. Mosquito-borne diseases kill more than 1 million people each year.

43. Key Concepts The Most Successful Animals
In terms of diversity, arthropods are the most successful animals
Crustaceans abound in the seas and insects are the most diverse animal group on land
Insects play essential roles in ecosystems
They also have economic and health effects

44. 23.15 Echinoderms
Echinoderms belong to the deuterostome lineage – adults are radial, but larvae are bilateral, implying bilateral ancestry
echinoderms
Invertebrates with a water–vascular system
Spines and other hard parts embedded in the skin support the body
Includes sea stars, sea urchins, sea cucumbers, brittle stars, and sand dollars

45. Echinoderms
Figure Echinoderms. A,B Sea star. C Sea urchin. D Sea cucumber. Other members of this group include brittle stars and sand dollars.

46. Sea Star Characteristics
Sea stars have no central nervous system; eyespots at the tips of the arms detect light and movement
Sea stars usually prey on bivalve mollusks; using a water-vascular system with tube feet
water–vascular system
Of echinoderms, a system of fluid-filled tubes and tube feet that function in locomotion

47. Sea Star Body Plan

48. ossicle (tiny skeletal structure)
Sea Star Body Plan
upper stomach
gonad
spine
anus
lower stomach
coelom
digestive gland
eyespot
Figure Echinoderms. A,B Sea star. C Sea urchin. D Sea cucumber. Other members of this group include brittle stars and sand dollars.
spine
ossicle (tiny skeletal structure)
ampullae
tube feet
Fig b, p. 373

49. Key Concepts On the Road to Chordates
Echinoderms are on the same branch of the animal family tree as the vertebrates (animals that have a backbone)
Echinoderm adults have a spiny skin and a radially symmetrical body
The larvae show bilateral symmetry, indicating descent from a bilateral ancestor

50. Old Genes, New Drugs (revisited)
Marine invertebrates are a treasure trove of molecules with potential in industrial applications or as medicines
Cone snails, sponges, corals, crabs, and sea cucumbers all make compounds that show promise as drugs
However, species are disappearing as a result of habitat destruction and overharvesting