Post on 26-Dec-2015
Animals: The InvertebratesAnimals: The Invertebrates
Chapter 25Chapter 25
Characteristics of AnimalsCharacteristics of Animals
• Multicelled heterotrophic eukaryotesMulticelled heterotrophic eukaryotes
• Require oxygen for aerobic respirationRequire oxygen for aerobic respiration
• Reproduce sexually, and perhaps Reproduce sexually, and perhaps asexuallyasexually
• Motile at some stageMotile at some stage
• Develop from embryosDevelop from embryos
Major Major Animal Animal Phyla Phyla
Chordates
Echinoderms
Arthropods
Annelids
Mollusks
Rotifers
Roundworms
Flatworms
Cnidarians
SpongesMulticelled Ancestry
Radial Ancestry
Bilateral Ancestry
Coelomate Ancestry
Single-celled, protistanlike ancestorsFigure 25.2Page 415
SymmetrySymmetry
Radial Bilateral Figure 25.3Figure 25.3Page 416Page 416
dorsal
posterior
ventral
anterior
The GutThe Gut
• Region where food is digested and Region where food is digested and then absorbedthen absorbed
• Saclike gutSaclike gut– One opening for taking in food and One opening for taking in food and
expelling wasteexpelling waste
• Complete digestive systemComplete digestive system– Opening at both ends; mouth and anusOpening at both ends; mouth and anus
Body Cavities - AcoelomateBody Cavities - Acoelomate
epidermisgut cavity
no body cavity; region between gut and body wall packed with organs
Figure 25.4aPage 417
Body Cavities - PseudocoelBody Cavities - Pseudocoel
epidermis gut cavity
unlined body cavity (pseudocoel) around gut
Figure 25.4bPage 417
Body Cavities - CoelomBody Cavities - Coelom
gut cavity
peritoneumlined body cavity (coelom) Figure 25.4c
Page 417
SegmentationSegmentation
• Repeating series of body unitsRepeating series of body units
• Units may or may not be similar to Units may or may not be similar to one anotherone another
• Earthworms - segments appear Earthworms - segments appear similarsimilar
• Insects - segments may be fused Insects - segments may be fused and/or have specialized functionsand/or have specialized functions
Animal Origins Animal Origins
• Originated during the Precambrian Originated during the Precambrian
(1.2 billion - 670 million years ago)(1.2 billion - 670 million years ago)
• From what? Two hypotheses:From what? Two hypotheses:– Multinucleated ciliate became Multinucleated ciliate became
compartmentalizedcompartmentalized
– Cells in a colonial flagellate became Cells in a colonial flagellate became
specializedspecialized
Phylum PlacozoaPhylum Placozoa
• One living species, One living species,
Tricoplax adherensTricoplax adherens
• Simplest known Simplest known
animalanimal
• Two-layer body, Two-layer body,
3 mm across3 mm across
Figure 25.5Page 418
Sponges - Phylum Porifera Sponges - Phylum Porifera
• No symmetryNo symmetry
• No tissuesNo tissues
• No organsNo organs
• Reproduce sexuallyReproduce sexually
• Microscopic swimming larval stageMicroscopic swimming larval stage
Sponge StructureSponge Structure
central cavity
water out
water in
flagellum microvilli nucleus
glasslike structural elements
amoeboid cell
pore
semifluid matrix
flattened surface cells
Figure 25.7aPage 419
Phylum Cnidaria Phylum Cnidaria
• Only Only animals that animals that produce produce nematocystnematocystss
• Nerve netNerve net
• Hydrostatic Hydrostatic skeletonskeleton
• Saclike gutSaclike gutFigure 25.8Page 420
barbed thread inside capsule
capsule’s lid at free surface of epidermal cell
trigger
nematocyst
Cnidarian DiversityCnidarian Diversity
• ScyphozoansScyphozoans– JellyfishJellyfish
• AnthozoansAnthozoans– Sea anemonesSea anemones
– CoralsCorals
• HydrozoansHydrozoans
Two Main Body PlansTwo Main Body Plans
Figure 25.9 Page 420
outer epithelium (epidermis)
mesoglea(matrix)
inner epithelium (gastrodermis)
Medusa
Polyp
ObeliaObelia Life Cycle Life Cycle (Hydrozoan)(Hydrozoan)
reproductivepolyp
female medusa male medusa
sperm
zygote
ovum
planula
polyp forming
feeding polyp
Figure 25.10Page 421
Flatworms: Flatworms: Phylum Platyhelminthes Phylum Platyhelminthes
• Acoelomate, bilateral, Acoelomate, bilateral, cephalized animals cephalized animals
• All have simple or complex All have simple or complex organ systemsorgan systems
• Most are hermaphroditesMost are hermaphrodites
Three Classes Three Classes
• Turbellarians (Turbellaria)Turbellarians (Turbellaria)
• Flukes (Trematoda)Flukes (Trematoda)
• Tapeworms (Cestoda)Tapeworms (Cestoda)
Planarian Organ SystemsPlanarian Organ Systems
pharynx
protonephridia
flame cellnucleus
cilia
fluid filters through membrane foldsflame cell
opening of tubule at body surface
Fig. Fig. 25.11a,b25.11a,bPage 422Page 422
Planarian Organ SystemsPlanarian Organ Systems
brain nerve cord
genital poreoviducttestisovary
penis
Fig. 25.11cdFig. 25.11cdPage 422Page 422
Roundworms (Nematoda)Roundworms (Nematoda)
• False coelomFalse coelom• Complete digestive systemComplete digestive system
gonadpharynx intestine
false coelom
eggs in uterus anus
muscularized body wall
Figure Figure 25.1325.13Page 423Page 423
Flukes: Class TrematodaFlukes: Class Trematoda
• Parasitic wormsParasitic worms
• Complicated life Complicated life
cyclecycle
– Larval stage Larval stage
infects a mollusk infects a mollusk
– Adult infects a Adult infects a
vertebrate vertebrate
Ciliated larva
Worms mate in human host
Fertilized egg
Asexual reproduction in intermediate host
Larvae form, leave snail
Larvae bore into human skin
Southeast Asian blood fluke Figure 25.14Page 424
Tapeworms: Class CestodaTapeworms: Class Cestoda
Larvae encysted in muscle tissue
Intermediate host Mature proglottid with fertilized eggs
Scolex attaches to host intestinal wall
Definitive host
Figure 25.15Page 424
RotifersRotifers
• BilateralBilateral
• CephalizedCephalized
• False coelomFalse coelom
• Crown of cilia at Crown of cilia at
head endhead end
• Complete gutComplete gut
Figure 25.17Page 425
Two Coelomate LineagesTwo Coelomate Lineages
ProtostomesProtostomes
• MollusksMollusks
• AnnelidsAnnelids
• ArthropodsArthropods
DeuterostomesDeuterostomes
• EchinodermsEchinoderms
• Chordates Chordates
Cleavage PatternsCleavage Patterns
Protostome embryo(spiral cleavage)
Deuterostome embryo(radial cleavage)
In-text In-text figurefigurePage 426Page 426
• Bilateral, soft-bodied, coelomateBilateral, soft-bodied, coelomate
• Most have a shell or reduced version Most have a shell or reduced version of oneof one
• Mantle drapes over body and secretes Mantle drapes over body and secretes shellshell
• Most have a fleshy footMost have a fleshy foot
• Many have a radula for shredding foodMany have a radula for shredding food
Mollusks: Phylum MolluscaMollusks: Phylum Mollusca
• Gastropods Gastropods
• ChitinsChitins
• BivalvesBivalves
• CephalopodsCephalopods
Molluscan DiversityMolluscan Diversity
• Twisting of body Twisting of body parts during parts during larval larval development development
• Occurs only in Occurs only in gastropodsgastropods
TorsionTorsion
mouth
anusgill
Figure 25.18Page 426
Body Plan of a SnailBody Plan of a Snail
gillanus
radula
foot
mantle cavity
digestive gland
mantle
heart
Figure Figure 25.1825.18Page 426Page 426
Body Plan of a ClamBody Plan of a Clam
mouthretractor muscle
left mantle
retractor muscle
foot
palpsleft gill shell
Figure Figure 25.2125.21Page 429Page 429
CephalopodsCephalopods
• Only the nautilus retains external shellOnly the nautilus retains external shell
• Other cephalopods are streamlined, Other cephalopods are streamlined, active swimmersactive swimmers
• All move by jet propulsionAll move by jet propulsion– Water is forced out of mantle cavity Water is forced out of mantle cavity
through a funnel-shaped siphonthrough a funnel-shaped siphon
• Have large brains relative to body sizeHave large brains relative to body size
Cuttlefish Body PlanCuttlefish Body Plan
Closed circulatory system with heart Closed circulatory system with heart and accessory heartand accessory heart
stomachkidneyesophagus
digestive gland
brain
arm
jaw
tentacle radula
siphon
anusink sac
gillheart accessory
heart
reproductive organ
mantleinternal
shell
Figure 25.22Page 429
Segmented, coelomate wormsSegmented, coelomate worms
• Class Polychaeta Class Polychaeta
• Class Oligochaeta Class Oligochaeta
• Class Hirudinea Class Hirudinea
Annelids: Phylum AnnelidaAnnelids: Phylum Annelida
PolychaetesPolychaetes
• Most are marineMost are marine• Bristles extend Bristles extend
from paired, from paired, fleshy parapods fleshy parapods on each on each segment segment
• Head end is Head end is specialized specialized
Fig. 25.24cFig. 25.24cPage 430Page 430
“jaws”
toothlike structurespharynx (everted)antenna
palp (food handling)
tentacle
eyes
chemical-sensing pit
parapod
• Predators and parasitesPredators and parasites
• Less obvious body Less obvious body
segmentationsegmentation
• Most have sharp jaws Most have sharp jaws
Leeches - Class HirudineaLeeches - Class Hirudinea
No parapodia, few bristles per segmentNo parapodia, few bristles per segment
Earthworm - An OligochaeteEarthworm - An Oligochaete
Nerve cord
Nerve cord
Dorsal blood vessel
Nephridium
Coelom
Circular muscle
Longitudinal muscle
Seta (retracted)Figure Figure 25.25a25.25aPage 431Page 431
Earthworm NephridiumEarthworm Nephridiumbladderlike storage region of nephridium
nephridium’s thin loop reabsorbs some solutes, relinquishes them to blood
blood vessels
body wall
external pore (fluid containing wastes discharged here)
funnel (coelomic fluid with waste enters here)
Figure Figure 25.25b25.25bPage 431Page 431
Earthworm Circulatory Earthworm Circulatory SystemSystem
Hearts
Figure Figure 25.25c25.25cPage 431Page 431
Earthworm Digestive Earthworm Digestive SystemSystem
PharynxEsophagus
Crop Gizzard
Coelomic chambers
Mouth
Figure 25.25dFigure 25.25dPage 431Page 431
Earthworm Nervous SystemEarthworm Nervous System
Brain
Nerve cord Figure Figure 25.25e25.25ePage Page 431431
• The phylum with the greatest number The phylum with the greatest number of speciesof species
• Four lineages:Four lineages:– Trilobites (all extinct)Trilobites (all extinct)
– Chelicerates (spiders, mites, scorpions)Chelicerates (spiders, mites, scorpions)
– Crustaceans (crabs, shrimps, barnacles)Crustaceans (crabs, shrimps, barnacles)
– Uniramians (insects, centipedes, millipedes)Uniramians (insects, centipedes, millipedes)
Arthropods: Arthropods: Phylum ArthropodaPhylum Arthropoda
Adaptations for SuccessAdaptations for Success
• Hardened exoskeletonHardened exoskeleton
• Jointed appendagesJointed appendages
• Fused and modified segmentsFused and modified segments
• Respiratory structuresRespiratory structures
• Specialized sensory structuresSpecialized sensory structures
• Division of laborDivision of labor
Do not post on Internet
Figure 25.26Page 432
• Originated in seasOriginated in seas
• A few are still marine: horseshoe A few are still marine: horseshoe crabs, sea spiders crabs, sea spiders
• The arachnids are all terrestrialThe arachnids are all terrestrialSpiders Mites Spiders Mites
Scorpions ChiggersScorpions Chiggers
““Daddy longlegs” TicksDaddy longlegs” Ticks
CheliceratesChelicerates
Body Plan of a SpiderBody Plan of a Spider
eye
poison gland
chelicera
mouth
book lung
sperm receptacle
ovary silk gland
spinners
anus
Malpighian tubuledigestive glandheartbrain
pedipalp
Figure 25.28Page 433
• Most are marine, Most are marine, some freshwater, a some freshwater, a few terrestrialfew terrestrial
• Head has two pairs of Head has two pairs of
antenna, three pairs of antenna, three pairs of
food-handling food-handling
appendagesappendages
CrustaceansCrustaceans
Copepods
Crayfish
Barnacles
Lobsters
Shrimps
Crabs
Isopods (pillbugs)
Lobster Body PlanLobster Body Plan
antennae (two pairs)
one of two eyes
fused segments of cephalothorax
segments of abdomen
tail fin
swimmerets
five walking legs (five pairs total)
first leg
food-handling appendages (three pairs)
Figure 25.29aPage 434
Crab Life Crab Life CycleCycle
Larval and juvenile stages molt repeatedly and grow in size
egg
Figure 25.30Page 435
Millipedes and CentipedesMillipedes and Centipedes
• Segmented bodies with many legsSegmented bodies with many legs• MillipedesMillipedes
– Two pairs of legs per “segment”Two pairs of legs per “segment”– ScavengersScavengers
• CentipedesCentipedes– Flattened, with one pair of legs per Flattened, with one pair of legs per
segmentsegment– PredatorsPredators
Insect Body PlanInsect Body Plan
• Thorax usually has three pairs of Thorax usually has three pairs of legs and one or two pairs of wingslegs and one or two pairs of wings
• Abdomen contains most internal Abdomen contains most internal organs and specialized structure for organs and specialized structure for reproduction reproduction
• Three-part gutThree-part gut
• Malpighian tubules attach to midgut Malpighian tubules attach to midgut
and serve in elimination of wastesand serve in elimination of wastes
Insect HeadpartsInsect Headparts
antenna labrum
palps
maxilla
labium
mandible
GrasshopperButterfly
Fly
Mosquito
Figure Figure 25.3225.32Page 436Page 436
Insect DiversityInsect Diversity
• The only winged invertebratesThe only winged invertebrates
• More than 800,000 known speciesMore than 800,000 known species
• Most successful species are small Most successful species are small in size and have a great in size and have a great reproductive capacityreproductive capacity
adult
adult
adult
youngegg
nymphsegg
egg
Growth and molting
Incomplete metamorphosis
Complete metamorphosis
Types ofTypes ofInsect Insect DevelopmenDevelopmentt
larvae pupa
Different stages exploit different resources at different times
Unwelcome ArthropodsUnwelcome Arthropods
• Poisonous Poisonous spidersspiders
• Disease-carrying Disease-carrying ticksticks
• Venomous Venomous scorpionsscorpions
• Agricultural pests Agricultural pests Corn rootworm (Diabrotica virgifera)
Do not post on Internet
Figure 25.38Page 439
EchinodermsEchinoderms
• Deuterostomes Deuterostomes
• Body wall has spines Body wall has spines
or plates or plates
• No brainNo brain
• Adults are radial with Adults are radial with
bilateral featuresbilateral features
Do not post
photos on
Internet
Figure 25.39Page 440
Sea urchin
Sea cucumber
Brittle star
Echinoderm DiversityEchinoderm Diversity
• Crinoids (sea lilies and feather stars)Crinoids (sea lilies and feather stars)
• Sea starsSea stars
• Brittle starsBrittle stars
• Sea urchins, heart urchins, sand Sea urchins, heart urchins, sand
dollarsdollars
• Sea cucumbers Sea cucumbers
Body Plan of a Sea StarBody Plan of a Sea Star
eyespot
digestive gland
gonad
anus
lower stomach
upper stomach
coelomsieve plate
Figure 25.40aPage 441
Water Vascular SystemWater Vascular System
sieve plate
ampulla
Figure Figure 25.40b25.40bPage 441Page 441