3. Crustaceans are nearly all aquatic. They include crabs, shrimp, and barnacles, which feed with jointed appendages. 4. Insects are the fourth lineage of arthropods, addressed next Arthropods are segmented animals with jointed appendages and an exoskeleton © 2012 Pearson Education, Inc.

Figure 18.11F A ghost crab (body about 2.5 cm across) Goose barnacles (about 2 cm high)

Figure 18.11F_1 Goose barnacles (about 2 cm high)

Figure 18.11F_2 A ghost crab (body about 2.5 cm across)

 70% of all identified animal species are insects. –There may be as many as 30 million insect species.  The body of an insect typically includes –a head, –thorax, –abdomen, –three sets of legs, and –wings (with few exceptions) EVOLUTION CONNECTION: Insects are the most successful group of animals © 2012 Pearson Education, Inc.

 The extraordinary success of insects is due to –body segmentation, –an exoskeleton, –jointed appendages, –flight, –a waterproof cuticle, and –a complex life cycle with short generations and large numbers of offspring EVOLUTION CONNECTION: Insects are the most successful group of animals © 2012 Pearson Education, Inc.

 Insect life cycles often include metamorphosis, during which the animal takes on different body forms as it develops from larva to adult. –More than 80% of insect species undergo complete metamorphosis in which a free-living larva transforms from a pupa into an adult. –Other insect species undergo incomplete metamorphosis in which the transition from larva to adult is achieved through multiple molts, but without forming a pupa EVOLUTION CONNECTION: Insects are the most successful group of animals © 2012 Pearson Education, Inc. Video: Butterfly Emerging Video: Bee Pollinating

Figure 18.12A Larva (grub, up to 12 cm length) Pupa Adult (up to 4 cm length)

Figure 18.12A_1 Larva (grub, up to 12 cm length)

Figure 18.12A_2 Pupa

Figure 18.12A_3 Adult (up to 4 cm length)

Figure 18.12B Antenna HeadThoraxAbdomen Specialized jumping legs Eye Mouthparts Walking legs Wings (extensions of cuticle)

 Modular body plan –The adult body parts of insects are formed by the fusion of embryonic segments identical to each other. –The insect body plan is essentially modular in that each embryonic segment develops independently. –Homeotic genes act to modify the structure of insect segments and their appendages EVOLUTION CONNECTION: Insects are the most successful group of animals © 2012 Pearson Education, Inc.

 Insect mouthparts are adapted for various types of feeding, such as –chewing (grasshoppers), –biting and tearing prey (mantids), –lapping up fluids (houseflies), and –piercing and sucking fluids of plants (aphids) and animals (mosquitoes) EVOLUTION CONNECTION: Insects are the most successful group of animals © 2012 Pearson Education, Inc.

 Insects have three pairs of legs, which are adapted for –walking, –jumping, –grasping prey, –digging in soil, or –paddling on water EVOLUTION CONNECTION: Insects are the most successful group of animals © 2012 Pearson Education, Inc.

 Wings –Most adult insects have one or two pairs of wings, allowing dispersal and escape from predators. –Because wings are extensions of the cuticle, insects have acquired flight without sacrificing any legs.  Protective color patterns –Many insects have protective color patterns and disguises, including modifications to antennae, wings, and bodies EVOLUTION CONNECTION: Insects are the most successful group of animals © 2012 Pearson Education, Inc.

Figure 18.12C A stick insect A leaf-mimic katydid A caterpillar resembling a bird dropping

Figure 18.12C_1 A stick insect

Figure 18.12C_2 A leaf-mimic katydid

Figure 18.12C_3 A caterpillar resembling a bird dropping

Figure 18.12D

Figure 18.12E

Figure 18.12E_1

Figure 18.12E_2

 Echinoderms (phylum Echinodermata) are –a diverse group including sea stars, sand dollars, and sea urchins, –slow-moving or sessile, –all marine, –radially symmetrical, and –deuterostomes (along with the chordates) Echinoderms have spiny skin, an endoskeleton, and a water vascular system for movement © 2012 Pearson Education, Inc.

 Echinoderms have –an endoskeleton of hard calcareous plates under a thin skin, –a water vascular system based on a network of water- filled canals that branch into extensions called tube feet, and –the ability to regenerate lost arms Echinoderms have spiny skin, an endoskeleton, and a water vascular system for movement © 2012 Pearson Education, Inc. Video: Echinoderm Tube Feet

Figure 18.13A Anus Stomach Spines Tube feet Canals

Figure 18.13B Tube foot

Figure 18.13C Spines Tube feet

 Chordates (phylum Chordata) are defined by –a dorsal, hollow nerve cord, –a flexible, supportive notochord, –pharyngeal slits, and –a muscular post-anal tail Our own phylum, Chordata, is distinguished by four features © 2012 Pearson Education, Inc.

 The simplest chordates are tunicates and lancelets, which –do not have a backbone and –use their pharyngeal slits for suspension feeding. –Adult tunicates are stationary and attached, while the tunicate larva is a tadpole-like organism. –Lancelets are small, bladelike chordates that live in marine sands Our own phylum, Chordata, is distinguished by four features © 2012 Pearson Education, Inc.

Figure 18.14A Post-anal tail Dorsal, hollow nerve cord Notochord Mouth Muscle segments Pharyngeal slits Larva Adult (about 3 cm high) Excurrent siphon

Figure 18.14A_1 Adult (about 3 cm high) Excurrent siphon

Figure 18.14A_2 Post-anal tail Dorsal, hollow nerve cord Notochord Mouth Muscle segments Pharyngeal slits Larva

Figure 18.14B Head Mouth Pharynx Pharyngeal slits Dorsal, hollow nerve cord Notochord Post-anal tail Water exit Anus Segmental muscles Digestive tract

Figure 18.14B_1 Head Mouth Pharynx Pharyngeal slits Dorsal, hollow nerve cord Notochord Post-anal tail Water exit Anus Segmental muscles Digestive tract

Figure 18.14B_2

ANIMAL PHYLOGENY AND DIVERSITY REVISITED © 2012 Pearson Education, Inc.

 Biologists used evidence from the fossil record, morphology, and embryology to make hypotheses about the evolutionary history of animal groups.  Recently, scientists have accumulated molecular data such as DNA sequences that shed new light on these phylogenetic relationships.  Figure presents a slightly revised tree based on this new molecular data An animal phylogenetic tree is a work in progress © 2012 Pearson Education, Inc.

Figure No true tissues Ancestral colonial protist Radial symmetry True tissues Bilateral symmetry Sponges Cnidarians Flatworms Molluscs Annelids Nematodes Arthropods Echinoderms Chordates Deuterostomes Ecdysozoans Lophotrochozoans Bilaterians Eumetazoans

Figure 18.15_1 No true tissues Ancestral colonial protist Radial symmetry Sponges Cnidarians Eumetazoans True tissues

Figure 18.15_2 True tissues Bilateral symmetry Flatworms Molluscs Annelids Nematodes Arthropods Ecdysozoans Bilaterians Ancestral colonial protist Lophotrochozoans Eumetazoans

Figure 18.15_3 True tissues Bilateral symmetry Bilaterians Ancestral colonial protist Eumetazoans Echinoderms Chordates Deuterostomes

 Genes responsible for building animal bodies are shared by virtually every member of the animal kingdom.  These ancient genes are the master control genes called homeotic genes.  Changes in the regulation of homeotic gene expression have been significant factors in the evolution of animal diversity EVOLUTION CONNECTION: The genes that build animal bodies are ancient © 2012 Pearson Education, Inc.

Figure 18.16A

Figure 18.16B Antenna Appendages

Figure 18.16B_1 Antenna Appendages

Figure 18.16B_2 Antenna Appendages

1.Describe the defining characteristics of animals. 2.Describe the general animal life cycle and the basic animal body plan. 3.Describe the Cambrian “explosion” of animal diversity and two hypotheses that have been advanced to explain its occurrence. 4.Explain how a hydrostatic skeleton helps an animal keep its shape and move. You should now be able to © 2012 Pearson Education, Inc.

5.Characterize the nine animal phyla discussed in this chapter in terms of the following traits: a. presence or absence of true tissues, b. no symmetry, radial symmetry, or bilateral symmetry, c. no coelom, a pseudocoelom, or a true coelom, and d. protostomes or deuterostomes. 6.Describe the characteristics of and distinguish between each of the following phyla: Porifera, Cnidaria, Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda, Echinodermata, and Chordata. You should now be able to © 2012 Pearson Education, Inc.

7.Define segmentation, explain its functions, and note the animal phyla where it occurs. 8.Compare the characteristics of the four major arthropod lineages. 9.Describe the common characteristics of insects. 10.Compare the phylogenetic relationships in Figures 18.4 and 18.15, noting similarities and differences. 11.Explain what we have learned about the evolution of life from the study of “evo-devo.” You should now be able to © 2012 Pearson Education, Inc.

Figure 18.UN01