Chapter 33 Invertebrates. LE 33-2 Deuterostomia Bilateria Eumetazoa Ancestral colonial choanoflagellate Porifera Cnidaria Other bilaterians (including.

Chapter 33Chapter 33

InvertebratesInvertebrates

LE 33-2

Deuterostomia

Bilateria

Eumetazoa

Ancestral colonialchoanoflagellate

Po

rife

ra

Cn

idar

ia

Oth

er b

ilate

rian

s (i

ncl

ud

ing

Nem

ato

da,

Art

hro

po

da,

Mo

llusc

a, a

nd

An

nel

ida)

Ch

ord

ata

Ech

ino

der

mat

a

LE 33-3a

250 µm

A sponge A jelly

A placozoan (LM) A kinorhynch (LM)

0.5 mm

A marine flatworm A rotifer (LM)

Ectoprocts Phoronids

LE 33-3b

A brachiopod A ribbon worm

5 mm

An acanthocephalan A ctenophore, or comb jelly

A marine annelidAn octopus

A loriciferan (LM)

50 µm

A priapulan

LE 33-3c

A roundworm A scorpion(an arachid)

100 µm

A cycliophoran (colorized SEM)

100 µm

Tardigrades (colorized SEM)

An onychophoran An acorn worm

A sea urchin A tunicate

SpongesSponges

CharacteristicsCharacteristics– Suspension feedersSuspension feeders– HermaphroditesHermaphrodites– SessileSessile

StructureStructure– SpongocoelSpongocoel– OsculumOsculum– ChoanocytesChoanocytes– MesohylMesohyl– AmoebocytesAmoebocytes

LE 33-4

Choanocytes

Flagellum

Osculum

Phagocytosis offood particles

Food particlesin mucus Choanocyte

Amoebocyte

Collar

Spicules

Amoebocyte

Waterflow

Mesohyl

Epidermis

Porocytes

Spongocoel

Azure vase sponge(Callyspongia plicifera)

CnidariansCnidarians

CharacteristicsCharacteristics– Radial symmetryRadial symmetry– Gastrovascular cavityGastrovascular cavity– Cnidocytes, cnidae, and nematocystsCnidocytes, cnidae, and nematocysts– CarnivoresCarnivores

Body planBody plan– PolypsPolyps– MedusaMedusa

LE 33-5

Tentacle

Gastrovascularcavity

Gastrodermis

Mesoglea

Epidermis

TentacleMouth/anus

Mouth/anusPolyp

Bodystalk

Medusa

LE 33-6

Tentacle

“Trigger”

Nematocyst

Coiled threadCnidocyte

Prey

Dischargeof thread

Four classes of CbidariaFour classes of Cbidaria

HydrozoansHydrozoans– Both polyp and medusa stagesBoth polyp and medusa stages

ScyphozoansScyphozoans– Poly stage reduced, free-swimmingPoly stage reduced, free-swimming

CubozoansCubozoans– Box-shaped medusae, complex eyesBox-shaped medusae, complex eyes

AnthozoansAnthozoans– No medusa stage, most sessileNo medusa stage, most sessile

Table 33-1

LE 33-7

Hydrozoans

Scyphozoans (jellies) Cubozoan (sea wasp) Anthozoan (sea anemone)

LE 33-8–3

Key

Feedingpolyp

Reproductivepolyp

Medusabud

Gonad

Medusa

Haploid (n)Diploid (2n)

ASEXUALREPRODUCTION(BUDDING)Portion of

a colonyof polyps

1 mm

MEIOSIS

FERTILIZATION

Egg Sperm

Zygote

SEXUALREPRODUCTION

Developingpolyp

Planula(larva)

Maturepolyp

Clade Bilateria (Bilateral symmetry)Clade Bilateria (Bilateral symmetry)Phyla:Phyla:

Platyhelminthes (Flatworms)Platyhelminthes (Flatworms)– Live in marine, freshwater and damp terrestrial habitatsLive in marine, freshwater and damp terrestrial habitats– Acoelomates, triplobastic developmentAcoelomates, triplobastic development– Flat shape - adaptationFlat shape - adaptation

RotiferaRotifera– Live in marine, freshwater and damp soilLive in marine, freshwater and damp soil– Alimentary canal replaces gastrovascular cavityAlimentary canal replaces gastrovascular cavity– PseudocoelomatesPseudocoelomates– ParthenogenesisParthenogenesis

Table 33-2

LE 33-10

Gastrovascularcavity

Pharynx

Ganglia

Eyespots

Ventral nerve cords

LE 33-12

Proglottids withreproductive structures

Scolex Hooks

Sucker

200 µm

LE 33-13

0.1 mm

More Phyla of BilateriaMore Phyla of Bilateria

LophophoratesLophophorates– Ectoprocta, Phoronida, and BrachiopodaEctoprocta, Phoronida, and Brachiopoda– Have lophphoreHave lophphore– U-shaped alimentary canalU-shaped alimentary canal– No distinct headNo distinct head

NemerteaNemertea– Ribbon wormsRibbon worms– Have alimentary canal (unlike flatworms)Have alimentary canal (unlike flatworms)– Closed circulatory system (unlike flatworms)Closed circulatory system (unlike flatworms)

LE 33-14

Lophophore

Ectoprocts Phoronids Brachiopods

Lophophore

Figure 33-15

MolluscsMolluscs

Snails, slugs, oysters, clams, octopi, squidSnails, slugs, oysters, clams, octopi, squid Most marineMost marine Soft-bodied, hard shell (most)Soft-bodied, hard shell (most) Similar body planSimilar body plan

– Muscular footMuscular foot– Visceral massVisceral mass– MantleMantle– Many also have mantle cavity, radulaMany also have mantle cavity, radula

Life cycle – most have separate sexes, larval Life cycle – most have separate sexes, larval stage (trochophore)stage (trochophore)

LE 33-16

NephridiumCoelom

Mantle

Heart

Anus

Mantlecavity

RadulaShell

Stomach

Intestine

Nervecords

EsophagusMouth

Gill

Foot

RadulaMouth

Visceral mass

Gonads

Figure 33-17

LE 33-18

A land snail

A sea slug. Nudibranchs, or sea slugs, lost their shell during their evolution.

LE 33-19

Stomach Intestine

Mouth

Anus

Mantlecavity

Figure 33-20

LE 33-21

Mouth

Anus

Mantle

Shell

Gut

Hinge areaCoelom

Heart

Excurrentsiphon

Adductormuscle

Waterflow

IncurrentsiphonGill

Mantlecavity

Foot

Palp

LE 33-22LE 33-22

Octopuses are considered among the most intelligent invertebrates.

Squids are speedy carnivores with beaklike jaws and well-developed eyes.

Chambered nautiluses are the only living cephalopods with an external shell.

Annelids – Segmented wormsAnnelids – Segmented worms

LE 33-23

Epidermis Coelom

Circular muscle

Longitudinal muscle

Dorsal vessel

Chaetae

Cuticle

Septum (partitionbetween segments)

Metanephridium

Anus

Clitellum

Crop

Ventral vessel

Nephrostome

Nervecords

Intestine

EsophagusPharynx

Cerebral ganglia

Mouth

Giant Australian earthworm

Subpharyngealganglion

Circulatorysystem

Ventral nerve cordswith segmentalganglia

Gizzard

Intestine

Metanephridium

NematodesNematodes

RoundwormsRoundworms No segmented body, cylindrical bodiesNo segmented body, cylindrical bodies PseudocoelomatesPseudocoelomates Have a cuticleHave a cuticle Mostly sexual reproductionMostly sexual reproduction Examples: Examples:

– C. elegansC. elegans– Trichinella spiralisTrichinella spiralis

LE 33-26

25 µm

LE 33-27

50 µmEncysted juveniles Muscle tissue

ArthropodsArthropods

General characteristicsGeneral characteristics– SegmentedSegmented– CoelomatesCoelomates– ExoskeletonsExoskeletons– Open circulatory systemsOpen circulatory systems– Specialized organs for gas exchangeSpecialized organs for gas exchange

Table 33-5

LE 33-29

Antennae(sensoryreception)

HeadThorax

Cephalothorax Abdomen

Swimmingappendages(two setslocated underabdomen

Walking legs

Mouthparts (feeding)Pincer (defense)

Figure 33-30

LE 33-31

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.

50 µm

LE 33-32

Intestine

Silk gland

Gonopore(exit for eggs) Sperm

receptacle

Book lung

Chelicera Pedipalp

Poisongland

Eyes

Brain

Stomach

Heart

Spinnerets

Anus

Ovary

Digestivegland

Figure 33-33

Figure 33-34

LE 33-35

Compound eye

Antennae

Abdomen Thorax Head

Anus

Vagina

Heart

Malpighian tubules

Ovary

Tracheal tubesNerve cords

Mouthparts

Cerebral ganglionCrop

Dorsalartery

LE 33-36

Larva (caterpillar)Pupa

Pupa

Emerging adult

Adult

LE 33-37aA

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Germancockroach

LE 33-37bA

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Japanesebeetle

LE 33-37cA

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Earwig

LE 33-37dA

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Horsefly

LE 33-37eA

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Leaf-footedbug

LE 33-37fA

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Cicada-killer wasp

LE 33-37gA

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Termite

LE 33-37aB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Swallowtailbutterfly

LE 33-37bB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Dragonfly

LE 33-37cB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Katydid

LE 33-37dB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Stick insect

LE 33-37eB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Humanbodylouse

LE 33-37fB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Flea

LE 33-37gB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Silverfish

LE 33-37hB

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.

ORDERAPPROXIMATE

NUMBER OFSPECIES

MAIN CHARACTERISTICS EXAMPLES

Caddisfly

Figure 33-38a

Figure 33-38b

Figure 33-38c

EchinodermsEchinoderms

Deuterostomes (like chordates)Deuterostomes (like chordates) Slow-moving or sessileSlow-moving or sessile EndoskeletonsEndoskeletons Water vascular system and tube feetWater vascular system and tube feet Sexual reproductionSexual reproduction Larvae – bilateral, adults – radial symmetryLarvae – bilateral, adults – radial symmetry

Table 33-6

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)

Table 33-7