1. Chapter 33
Invertebrates

2. LE 33-2 Porifera Cnidaria Echinodermata Chordata
Other bilaterians (including
Nematoda, Arthropoda,
Mollusca, and Annelida)
Deuterostomia
Bilateria
Eumetazoa
Ancestral colonial
choanoflagellate

3. LE 33-3a A sponge A jelly 0.5 mm 250 µm A placozoan (LM)
A kinorhynch (LM)
A marine flatworm
A rotifer (LM)
Ectoprocts
Phoronids

4. LE 33-3b A brachiopod A ribbon worm 5 mm An acanthocephalan
A ctenophore, or comb jelly
An octopus
A marine annelid
50 µm
A loriciferan (LM)
A priapulan

5. LE 33-3c A roundworm A scorpion (an arachid) 100 µm 100 µm
A cycliophoran (colorized SEM)
Tardigrades (colorized SEM)
An onychophoran
An acorn worm
A sea urchin
A tunicate

6. Sponges Characteristics Structure Suspension feeders Hermaphrodites
Sessile
Structure
Spongocoel
Osculum
Choanocytes
Mesohyl
Amoebocytes

7. LE 33-4
Flagellum
Food particles
in mucus
Choanocyte
Choanocytes
Collar
Osculum
Azure vase sponge
(Callyspongia plicifera)
Spongocoel
Phagocytosis of
food particles
Amoebocyte
Porocytes
Spicules
Epidermis
Water
flow
Amoebocyte
Mesohyl

8. Cnidarians Characteristics Body plan Radial symmetry
Gastrovascular cavity
Cnidocytes, cnidae, and nematocysts
Carnivores
Body plan
Polyps
Medusa

9. Mouth/anus Tentacle Polyp Medusa Gastrovascular cavity Gastrodermis
Mesoglea
Body
stalk
Epidermis
Tentacle
Mouth/anus

10. Prey Tentacle “Trigger” Discharge of thread Nematocyst Coiled thread
Cnidocyte

11. Four classes of Cbidaria
Hydrozoans
Both polyp and medusa stages
Scyphozoans
Poly stage reduced, free-swimming
Cubozoans
Box-shaped medusae, complex eyes
Anthozoans
No medusa stage, most sessile

12. Table 33-1

13. LE 33-7 Scyphozoans (jellies) Cubozoan (sea wasp) Anthozoan
(sea anemone)
Hydrozoans

14. LE 33-8–3 Reproductive polyp Feeding polyp Medusa bud MEIOSIS Gonad
SEXUAL
REPRODUCTION
Egg
Sperm
ASEXUAL
REPRODUCTION
(BUDDING)
Portion of
a colony
of polyps
FERTILIZATION
Zygote
Developing
polyp
Mature
polyp
Planula
(larva)
Key
Haploid (n)
1 mm
Diploid (2n)

15. Clade Bilateria (Bilateral symmetry) Phyla:
Platyhelminthes (Flatworms)
Live in marine, freshwater and damp terrestrial habitats
Acoelomates, triplobastic development
Flat shape - adaptation
Rotifera
Live in marine, freshwater and damp soil
Alimentary canal replaces gastrovascular cavity
Pseudocoelomates
Parthenogenesis

16. Table 33-2

17. Pharynx Gastrovascular cavity Eyespots Ganglia Ventral nerve cords
LE 33-10
Pharynx
Gastrovascular
cavity
Eyespots
Ganglia
Ventral nerve cords

18. reproductive structures
LE 33-12
Proglottids with
reproductive structures
200 µm
Scolex
Hooks
Sucker

19. LE 33-13
0.1 mm

20. More Phyla of Bilateria
Lophophorates
Ectoprocta, Phoronida, and Brachiopoda
Have lophphore
U-shaped alimentary canal
No distinct head
Nemertea
Ribbon worms
Have alimentary canal (unlike flatworms)
Closed circulatory system (unlike flatworms)

21. LE 33-14
Lophophore
Lophophore
Ectoprocts
Phoronids
Brachiopods

22. Figure 33-15

23. Molluscs Snails, slugs, oysters, clams, octopi, squid Most marine
Soft-bodied, hard shell (most)
Similar body plan
Muscular foot
Visceral mass
Mantle
Many also have mantle cavity, radula
Life cycle – most have separate sexes, larval stage (trochophore)

24. Visceral mass Coelom Heart Intestine Nephridium Gonads Mantle Stomach
Radula
Mantle
cavity
Shell
Mouth
Radula
Anus
Gill
Mouth
Nerve
cords
Foot
Esophagus

25. Figure 33-17

26. A sea slug. Nudibranchs, or sea slugs,
LE 33-18
A land snail
A sea slug. Nudibranchs, or sea slugs,
lost their shell during their evolution.

27. LE 33-19
Stomach
Intestine
Mantle
cavity
Anus
Mouth

28. Figure 33-20

29. LE 33-21
Coelom
Hinge area
Mantle
Gut
Heart
Adductor
muscle
Shell
Anus
Mouth
Excurrent
siphon
Palp
Water
flow
Foot
Mantle
cavity
Incurrent
siphon
Gill

30. LE 33-22
Squids are speedy carnivores with beaklike jaws and well-developed eyes.
Chambered nautiluses are the only living cephalopods with an external shell.
Octopuses are considered among the most intelligent invertebrates.

31. Annelids – Segmented worms

32. Giant Australian earthworm Cerebral ganglia Gizzard Mouth
LE 33-23
Cuticle
Epidermis
Coelom
Septum (partition
between segments)
Circular muscle
Longitudinal muscle
Metanephridium
Anus
Dorsal vessel
Chaetae
Intestine
Ventral vessel
Nerve
cords
Nephrostome
Metanephridium
Clitellum
Esophagus
Crop
Pharynx
Intestine
Giant Australian earthworm
Cerebral ganglia
Gizzard
Mouth
Ventral nerve cords
with segmental
ganglia
Subpharyngeal
ganglion
Circulatory
system

33. Nematodes Roundworms No segmented body, cylindrical bodies
Pseudocoelomates
Have a cuticle
Mostly sexual reproduction
Examples:
C. elegans
Trichinella spiralis

34. LE 33-26
25 µm

35. Encysted juveniles Muscle tissue 50 µm

36. Arthropods General characteristics Segmented Coelomates Exoskeletons
Open circulatory systems
Specialized organs for gas exchange

37. Table 33-5

38. Cephalothorax Abdomen Thorax Head Antennae (sensory reception)
LE 33-29
Cephalothorax
Abdomen
Thorax
Head
Antennae
(sensory
reception)
Swimming
appendages
(two sets
located under
abdomen
Walking legs
Pincer (defense)
Mouthparts (feeding)

39. Figure 33-30

40. LE 33-31
50 µm
Scorpions have pedipalps that are pincers specialized for defense and the capture of food. The tip of the tail bears a poisonous stinger.
Dust mites are ubiquitous scavengers in human dwellings but are harmless except to those people who are allergic to them (colorized SEM).
Web-building spiders are generally most active during the daytime.

41. Stomach Intestine Heart Brain Digestive gland Eyes Ovary Poison gland
LE 33-32
Stomach
Intestine
Heart
Brain
Digestive
gland
Eyes
Ovary
Poison
gland
Anus
Book lung
Spinnerets
Gonopore
(exit for eggs)
Chelicera
Pedipalp
Sperm
receptacle
Silk gland

42. Figure 33-33

43. Figure 33-34

44. LE 33-35 Abdomen Thorax Head Compound eye Antennae Dorsal artery Crop
Cerebral ganglion
Anus
Heart
Vagina
Malpighian tubules
Ovary
Tracheal tubes
Mouthparts
Nerve cords

45. LE 33-36
Larva (caterpillar)
Pupa
Pupa
Emerging adult
Adult

46. LE 33-37aA APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Blattodea
4,000
Cockroaches have a dorsoventrally flattened body, with legs modified for rapid running. Forewings, when present, are leathery, whereas hind wings are fanlike. Fewer than 40 cockroach species live in houses; the rest exploit habitats ranging from tropical forest floors to caves and deserts.
German
cockroach

47. LE 33-37bA APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Coleoptera
350,000
Beetles comprise the most species-rich order of insects. They have two pairs of wings, one of which is thick and leathery, the other membranous. They have an armored exoskeleton and mouthparts adapted for biting and chewing. Beetles undergo complete metamorphosis.
Japanese
beetle

48. LE 33-37cA APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Dermaptera
1,200
Earwigs are generally nocturnal scavengers. While some species are wingless, others have two pairs of wings, one of which is thick and leathery, the other membranous. Earwigs have biting mouthparts and large posterior pincers. They undergo incomplete metamorphosis.
Earwig

49. LE 33-37dA APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Diptera
151,000
Dipterans have one pair of wings; the second pair has become modified into balancing organs called halteres. Their head is large and mobile; their mouthparts are adapted for sucking, piercing, or lapping. Dipterans undergo complete metamorphosis. Flies and mosquitoes are among the best-known dipterans, which live as scavengers, predetors, and parasites.
Horsefly

50. LE 33-37eA APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Hemiptera
85,000
Hemipterans are so-called “true bugs,” including bed bugs, assassin bugs, and chinch bugs. (Insects in other orders are sometimes erroneously called bugs.) Hemipterans have two pairs of wings, one pair partly leathery, the other membranous. They have piercing or sucking mouthparts and undergo incomplete metamorphosis.
Leaf-
footed
bug

51. LE 33-37fA APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Hymenoptera
125,000
Ants, bees, and wasps are generally highly social insects. They have two pairs of membranous wings, a mobile head, and chewing or sucking mouthparts. The females of many species have a posterior stinging organ. Hymenopterans undergo complete metamorphosis.
Cicada-killer wasp

52. LE 33-37gA APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Isoptera
2,000
Termites are widespread social insects that produce enormous colonies. It had been estimated that there are 700 kg of termites for every person on Earth! Some termites have two pairs of membranous wings, while others are wingless. They feed on wood with the aid of microbial symbionts carried in specialized chambers in their hindgut.
Termite

53. LE 33-37aB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Lepidoptera
120,000
Butterflies and moths are among the best-known insects. They have two pairs of wings covered with tiny scales. To feed, they uncoil a long proboscis. Most feed on nectar, but some species feed on other substances, including animal blood or tears.
Swallowtail
butterfly

54. LE 33-37bB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Odonata
5,000
Dragonflies and damselflies have two pairs of large, membranous wings. They have an elongated abdomen, large, compound eyes, and chewing mouthparts. They undergo incomplete metamorphosis and are active predators.
Dragonfly

55. LE 33-37cB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Orthoptera
13,000
Grasshoppers, crickets, and their relatives are mostly herbivorous. They have large hind legs adapted for jumping, two pairs of wings (one leathery, one membranous), and biting or chewing mouthparts. Males commonly make courtship sounds by rubbing together body parts, such as a ridge of their hind leg. Orthopterans undergo incomplete metamorphosis.
Katydid

56. LE 33-37dB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Phasmida
2,600
Stick insects and leaf insects are exquisite mimics of plants. The eggs of some species even mimic seeds of the plants on which the insects live. Their body is cylindrical or flattened dorsoventrally. They lack forewings but have fanlike hind wings. Their mouthparts are adapted for biting or chewing.
Stick insect

57. LE 33-37eB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Phthiraptera
2,400
Commonly called sucking lice, these insects spend their entire life as an ectoparasite feeding on the hair or feathers of a single host. Their legs, equipped with clawlike tarsi, are adapted for clinging to their hosts. They lack wings and have reduced eyes. Sucking lice undergo incomplete metamorphosis.
Human
body
louse

58. LE 33-37fB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Siphonaptera
2,400
Fleas are bloodsucking ectoparasites on birds and mammals. Their body is wingless and laterally compressed. Their legs are modified for clinging to their hosts and for long-distance jumping. They undergo complete metamorphosis.
Flea

59. LE 33-37gB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Thysanura
450
Silverfish are small, wingless insects with a flattened body and reduced eyes. They live in leaf litter or under bark. They can also infest buildings, where they can become pests.
Silverfish

60. LE 33-37hB APPROXIMATE NUMBER OF SPECIES ORDER MAIN CHARACTERISTICS
EXAMPLES
Trichoptera
7,100
The larvae of caddisflies live in streams, where they make houses from sand grains, wood fragments, or other material held together by silk, Adults have two pairs of hairy wings and chewing or lapping mouthparts. They undergo complete metamorphosis.
Caddisfly

61. Figure 33-38a

62. Figure 33-38b

63. Figure 33-38c

64. Echinoderms Deuterostomes (like chordates) Slow-moving or sessile
Endoskeletons
Water vascular system and tube feet
Sexual reproduction
Larvae – bilateral, adults – radial symmetry

65. Table 33-6

66. LE 33-40 A sea star (class Asteroidea)
A brittle star (class Ophiuroidea)
A sea urchin (class Echinoidea)
A feather star (class Crinoidea)
A sea cucumber (class Holothuroidea)
A sea daisy (class Concentricycloidea)

67. Table 33-7