Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

1:​ ​INTRODUCTION

2

2:​ ​NATURAL​ ​SELECTION

2

2:​ ​CLASSIFICATION

3

2:​ ​PHYLOGENIES​ ​AND​ ​LINKING​ ​PHYLOGENY​ ​WITH​ ​CLASSIFICATION

3

2:​ ​THREE​ ​DOMAINS

5

3:​ ​PROKARYOTES

5

3:​ ​EUKARYOTES

7

3:​ ​SERIAL​ ​ENDOSYMBIONT​ ​THEORY​ ​(SET)

7

3:​ ​PROTISTS

8

4:​ ​ANIMAL​ ​DIVERSITY

9

18:​ ​THE​ ​GREAT​ ​ANIMAL​ ​RADIATION

11

5:​ ​PORIFERA

14

5:​ ​CTENOPHORA

14

5:​ ​CNIDARIA

15

5:​ ​ACOELA

16

6:​ ​LOPHOTROCHOZOA

16

6:​ ​PLATYHELMINTHES

16

7:​ ​ROTIFERA

18

7:​ ​ECTOPROCTA

19

7:​ ​BRACHIOPODA

20

8&9:​ ​MOLLUSCA

20

10:​ ​ANNELIDA

28

12:​ ​ECHINODERMATA

31

13,15,16,17,18,&19:​ ​ARTHROPODA

35

17:​ ​NEMATODA

52

Joanna​ ​Griffith​ ​(2017)

1:​ ​INTRODUCTION
Why​ ​study​ ​invertebrates?
○ There​ ​are​ ​5​ ​million​ ​different​ ​species,​ ​and​ ​only​ ​5%​ ​of​ ​them​ ​are​ ​vertebrates
○ Invertebrates​ ​are​ ​more​ ​diverse​ ​than​ ​vertebrates​ ​in​ ​form,​ ​ecology,​ ​and
morphological​ ​function
● Zoology:​ ​the​ ​study​ ​of​ ​animals
○ Animals​ ​are​ ​usually​ ​multicellular,​ ​heterotrophic,​ ​and​ ​eukaryotic,​ ​with​ ​tissues
that​ ​develop​ ​from​ ​embryonic​ ​layers,​ ​and​ ​they​ ​do​ ​not​ ​have​ ​cells​ ​with
supporting​ ​cell​ ​walls
■ Definition​ ​is​ ​not​ ​straightforward,​ ​there​ ​are​ ​always​ ​exceptions
○ The​ ​form​ ​of​ ​an​ ​animal​ ​can​ ​relate​ ​to:
■ Type​ ​of​ ​environment
■ Size​ ​of​ ​animal
■ Mode​ ​of​ ​existence
● Adaptation:​ ​animal​ ​form​ ​and​ ​function​ ​is​ ​correlated​ ​with​ ​the​ ​environment​ ​at​ ​all​ ​levels
of​ ​organisation
○ Convergent​ ​evolution:​ ​different​ ​evolutionary​ ​history,​ ​but​ ​similar​ ​solution
developed​ ​for​ ​the​ ​same​ ​problem​ ​(eg
...
​ ​Panthera​ ​leo)
○ Genus​ ​is​ ​always​ ​capitalised,​ ​whole​ ​binomial​ ​name​ ​in​ ​italics​ ​or​ ​underlined​ ​if
handwritten
○ Name​ ​tends​ ​to​ ​be​ ​informative​ ​about​ ​the​ ​distinguishing​ ​features​ ​of​ ​the
organism
● Hierarchical​ ​classifications
○ Domain
■ Kingdom
● Phylum
○ Class
■ Order
● Family
○ Genus
■ Species
● Taxon:​ ​taxonomic​ ​unit​ ​at​ ​each​ ​level
● Classification​ ​is​ ​informed​ ​by​ ​phylogenetics,​ ​but​ ​they​ ​are​ ​not​ ​the​ ​same​ ​thing
Cladistics
● Classification​ ​based​ ​on​ ​phylogeny​ ​(the​ ​evolutionary​ ​development​ ​of​ ​a​ ​species)
● Clades​ ​contain​ ​ancestral​ ​species​ ​and​ ​all​ ​of​ ​their​ ​descendants
○ Helps​ ​to​ ​identify​ ​groups​ ​that​ ​share​ ​a​ ​unique​ ​common​ ​ancestor
○ Nestled​ ​within​ ​larger​ ​clades
● A​ ​taxon​ ​from​ ​the​ ​Linnaean​ ​system​ ​is​ ​only​ ​equivalent​ ​to​ ​a​ ​clade​ ​if​ ​the​ ​clade​ ​is
monophyletic​ ​(a​ ​group​ ​of​ ​organisms​ ​all​ ​descended​ ​from​ ​a​ ​common​ ​ancestor)
● Monophyletic​ ​group:​ ​an​ ​ancestral​ ​species​ ​and​ ​all​ ​of​ ​its​ ​descendants
● Paraphyletic​ ​group:​ ​an​ ​ancestral​ ​species​ ​and​ ​some​ ​of​ ​its​ ​descendants
● Polyphyletic​ ​group:​ ​taxa​ ​with​ ​different​ ​ancestors
● Clades​ ​are​ ​inferred​ ​from​ ​shared​ ​derived​ ​characters​ ​(characteristics​ ​that​ ​differentiate
them​ ​from​ ​other​ ​clades,​ ​such​ ​as​ ​hair​ ​in​ ​mammals)
○ Not​ ​to​ ​be​ ​confused​ ​with​ ​shared​ ​ancestral​ ​characters​ ​(characteristics​ ​passed
on​ ​by​ ​the​ ​common​ ​ancestor,​ ​such​ ​as​ ​a​ ​backbone)
■ However,​ ​these​ ​shared​ ​ancestral​ ​characters​ ​can​ ​be​ ​used​ ​to
differentiate​ ​between​ ​larger​ ​clades​ ​(eg
...
​ ​wings​ ​in
bats​ ​and​ ​birds​ ​are​ ​homologous​ ​as​ ​flight​ ​structures)
■ Synapomorphies:​ ​characteristics​ ​present​ ​in​ ​an​ ​ancestral​ ​species​ ​and
shared​ ​exclusively​ ​(in​ ​more​ ​or​ ​less​ ​modified​ ​forms)​ ​by​ ​its​ ​evolutionary
descendants
○ Analogous​ ​structures:​ ​features​ ​in​ ​different​ ​organisms​ ​that​ ​appear​ ​similar​ ​but
are​ ​actually​ ​the​ ​result​ ​of​ ​convergent​ ​evolution​ ​(eg
...
​ ​brachiopods​ ​or
ectoprocts)​ ​or​ ​have​ ​a​ ​distinctive​ ​development​ ​stage​ ​as
trochophore​ ​larvae​ ​(eg
...
​ ​thermophiles,​ ​halophiles
○ Eukarya
■ All​ ​organisms​ ​with​ ​eukaryotic​ ​cells
● Cells​ ​with​ ​a​ ​nucleus
● Unicellular​ ​organisms,​ ​multicellular​ ​organisms,​ ​plants,​ ​animals,
fungi
○ Reflects​ ​that​ ​life​ ​is​ ​dominated​ ​by​ ​single-celled​ ​organisms
○ Kingdoms​ ​of​ ​Protista​ ​and​ ​Monera​ ​are​ ​no​ ​longer​ ​recognised
--------------------------------------------------------------------------------------------------------------------------●

3:​ ​PROKARYOTES
●

Collective​ ​biomass​ ​is​ ​10x​ ​that​ ​of​ ​eukaryotes
Joanna​ ​Griffith​ ​(2017)

●
●
●
●

●

●

●
●

●

Huge​ ​genetic​ ​diversity
Most​ ​are​ ​unicellular,​ ​some​ ​are​ ​colonial
Lack​ ​membrane-bound​ ​organelles
Range​ ​of​ ​nutritional​ ​modes
○ Autotrophs
■ Photoautotrophs
● Light​ ​as​ ​an​ ​energy​ ​source,​ ​CO​2​​ ​as​ ​a​ ​carbon​ ​source
● Eg
...
​ ​certain​ ​prokaryotes​ ​such​ ​as​ ​Sulfolobus
■ Heterotrophs
● Photoheterotrophs
○ Light​ ​as​ ​an​ ​energy​ ​source,​ ​organic​ ​compounds​ ​as​ ​a
carbon​ ​source
○ Eg
...
​ ​many​ ​prokaryotes​ ​such​ ​as​ ​Clostridium
Three​ ​main​ ​shapes
○ Rods​ ​(bacilli),​ ​eg
...
​ ​Staphylococcus​ ​aureus
○ Spirals​ ​(spirilla),​ ​eg
...
​ ​Giardia),​ ​Parabasalids​ ​(eg
...
​ ​Trypanosoma)
○ Chromalveolata
■ Based​ ​on​ ​DNA​ ​sequencing
■ Originated​ ​a​ ​billion​ ​years​ ​ago
■ Split​ ​into​ ​Alveolates​ ​and​ ​Stramenopiles
○ Rhizaria
○ Archaeplastida
■ Based​ ​on​ ​molecular​ ​systematics​ ​and​ ​cell​ ​structure
■ Eg
...
​ ​surface​ ​of​ ​embryo,​ ​outer​ ​layer​ ​of​ ​the​ ​animal,​ ​the​ ​central​ ​nervous
systems​ ​of​ ​some​ ​phyla
○ Endoderm
■ Eg
...
​ ​jellies
○ Triploblastic
■ Has​ ​three​ ​germ​ ​layers
■ Eg
...
​ ​earthworms
■ Pseudocoelomates
● Formed​ ​from​ ​mesoderm​ ​and​ ​ectoderm
● Eg
...
​ ​flatworms
Development
○ Protostome
■ Eg
...
​ ​echinoderms​ ​and​ ​chordates
■ Radial​ ​and​ ​indeterminate​ ​cleavage​ ​in​ ​the​ ​eight-cell​ ​stage​ ​(removing​ ​a
single​ ​cell​ ​has​ ​no​ ​effect​ ​on​ ​the​ ​finished​ ​organism​ ​and​ ​can​ ​even​ ​lead​ ​to
several​ ​blastopores​ ​developing)
■ Folds​ ​of​ ​archenteron​ ​form​ ​the​ ​coelom
Joanna​ ​Griffith​ ​(2017)

■ The​ ​blastopore​ ​develops​ ​into​ ​the​ ​anus,​ ​the​ ​mouth​ ​is​ ​secondary
Why​ ​is​ ​there​ ​so​ ​much​ ​functional​ ​diversity?
● Regulatory​ ​genes​ ​contain​ ​sets​ ​of​ ​DNA​ ​sequences​ ​called​ ​homeoboxes,​ ​which​ ​have
been​ ​very​ ​well​ ​conserved​ ​throughout​ ​evolution,​ ​and​ ​similar​ ​versions​ ​are​ ​present​ ​in​ ​all
animals
○ Despite​ ​this,​ ​the​ ​animal​ ​kingdom​ ​is​ ​very​ ​diverse
● mass/surface​ ​area​ ​ratios
○ V=pir​2​h
■ Assuming​ ​constant​ ​shape,​ ​volume​ ​is​ ​proportional​ ​to​ ​length​3​,​ ​and
surface​ ​area​ ​is​ ​proportional​ ​to​ ​length​2
■ Need​ ​for​ ​oxygen​ ​is​ ​proportional​ ​to​ ​volume,​ ​which​ ​is​ ​proportional​ ​to
length​3
■ External​ ​surface​ ​area​ ​available​ ​to​ ​absorb​ ​oxygen​ ​is​ ​proportional​ ​to
length​2
○ Surface​ ​area​ ​must​ ​keep​ ​pace​ ​with​ ​volume
■ Larger​ ​animals​ ​must​ ​be​ ​more​ ​morphologically​ ​complex​ ​in​ ​order​ ​to
absorb​ ​enough​ ​oxygen
● Tensile​ ​strength
○ Mass​ ​=​ ​load,​ ​which​ ​is​ ​proportional​ ​to​ ​length​3
○ Tensile​ ​strength​ ​is​ ​proportional​ ​to​ ​cross-sectional​ ​area,​ ​which​ ​is​ ​proportional
to​ ​length​2
● Compound​ ​eyes
○ Not​ ​primitive,​ ​just​ ​suited​ ​to​ ​smaller​ ​animals
■ Reduces​ ​refraction​ ​of​ ​light​ ​by​ ​providing​ ​a​ ​larger​ ​aperture
● Scale​ ​laws
○ Size​ ​affects​ ​speed/ability​ ​to​ ​jump/ability​ ​to​ ​fly/etc
...
5bya
● Tappania​ ​(eukaryote​ ​-​ ​protist)​ ​1
...
6bya
● Marella​ ​(eukaryote​ ​-​ ​animalia),​ ​0
...
​ ​Charniodiscus​ ​and
the​ ​sea​ ​pen),​ ​some​ ​don’t
○ Probably​ ​surface​ ​grazers
■ Bottom​ ​of​ ​ocean​ ​thought​ ​to​ ​be​ ​a​ ​microbial​ ​mat​ ​on​ ​top​ ​of​ ​anoxic
sediments
■ Trace​ ​fossils​ ​from​ ​550​ ​mya​ ​show​ ​no​ ​sign​ ​of​ ​burrowing
● The​ ​Cambrian​ ​explosion​ ​(Paleozoic​ ​era,​ ​542-251​ ​mya)
○ Rapid​ ​diversification​ ​between​ ​535​ ​and​ ​525​ ​mya
○ 50%​ ​of​ ​all​ ​extant​ ​phyla​ ​emerged​ ​in​ ​this​ ​period
○ Soft-bodied​ ​fossils​ ​found​ ​in​ ​the​ ​Burgess​ ​Shale​ ​(eg
...
7​ ​-​ ​2
...
​ ​Ediacaran​ ​fossils​ ​from​ ​Dengying​ ​formation​ ​(555​ ​mya)
● Inferred​ ​increase​ ​in​ ​O​2​​ ​accompanies​ ​the​ ​evolution​ ​of​ ​complex​ ​life
○ Aerobic​ ​respiration​ ​(36​ ​ATP​ ​molecules​ ​per​ ​glucose)​ ​is​ ​more​ ​productive​ ​than
anaerobic​ ​respiration​ ​(2​ ​ATP​ ​molecules​ ​per​ ​glucose)​ ​and​ ​is​ ​now​ ​easier
○ More​ ​oxygen​ ​=​ ​more​ ​energetic​ ​lifestyles
■ More​ ​predation,​ ​larger​ ​organisms
● Evidence​ ​for​ ​increased​ ​oxygen
○ Increase​ ​in​ ​carbon​ ​burial
○ The​ ​solubility​ ​of​ ​rare​ ​minerals​ ​changes​ ​in​ ​the​ ​presence​ ​of​ ​oxygen​ ​(eg
...
​ ​shells,​ ​hard​ ​exoskeletons
(eg
...
​ ​Treptichnus​ ​pedum)
○ Oxygen​ ​produces​ ​ozone,​ ​which​ ​reduces​ ​the​ ​incidence​ ​of​ ​UV​ ​in​ ​surface
waters​ ​and​ ​makes​ ​colonisation​ ​of​ ​land​ ​possible
The​ ​snowball​ ​Earth​ ​hypothesis
● Growing​ ​polar​ ​ice​ ​caps​ ​cause​ ​the​ ​Earth​ ​to​ ​freeze​ ​over,​ ​volcanic​ ​outgassing​ ​leads​ ​to​ ​a
build-up​ ​of​ ​volcanic​ ​CO​2​​ ​which​ ​melts​ ​the​ ​ice,​ ​high​ ​phosphorus​ ​levels​ ​in​ ​oceans​ ​cause
a​ ​huge​ ​global​ ​algal​ ​bloom
○ Photosynthesis​ ​of​ ​blue-green​ ​algae​ ​=​ ​O​2​​ ​levels​ ​increase
● Positive​ ​feedback​ ​(cooling)
○ Ice​ ​formation​ ​at​ ​poles​ ​increases​ ​the​ ​albedo​ ​effect,​ ​greater​ ​heat​ ​reflection,
runaway​ ​cooling​ ​exacerbated​ ​by​ ​having​ ​land​ ​masses​ ​at​ ​the​ ​equator,
weathering​ ​keeps​ ​removing​ ​CO​2​​ ​from​ ​the​ ​atmosphere​ ​even​ ​with​ ​icy​ ​poles
● Negative​ ​feedback​ ​(warming)
○ Volcanoes​ ​vent​ ​CO​2​,​ ​no​ ​removal​ ​by​ ​rain
○ When​ ​icy,​ ​no​ ​rock​ ​weathering​ ​to​ ​bind​ ​CO​2​​ ​to​ ​silica
○ Melting​ ​predicted​ ​to​ ​be​ ​rapid
The​ ​fossil​ ​record
● Many​ ​phyla​ ​appear​ ​suddenly​ ​as​ ​well-differentiated​ ​classes,​ ​eg
...

scorpions)
○ Paleozoic​ ​era​ ​finishes​ ​with​ ​the​ ​Permian​ ​mass​ ​extinction​ ​event,​ ​‘the​ ​great
dying’
● The​ ​Mesozoic​ ​era​ ​(251-65
...
5-present)
○ Mass​ ​extinction​ ​event​ ​at​ ​Cretaceous/Tertiary​ ​boundary
■ Dinosaurs​ ​disappeared,​ ​frogs​ ​survived
○ Rise​ ​of​ ​the​ ​mammals,​ ​exploited​ ​vacant​ ​niches
--------------------------------------------------------------------------------------------------------------------------5:​ ​PORIFERA
● About​ ​5000​ ​species​ ​of​ ​sponges
● marine/freshwater
● Large​ ​size​ ​range,​ ​from​ ​mm​ ​to​ ​m
Body​ ​plan
● Diploblastic​ ​(only​ ​two​ ​embryonic​ ​cell​ ​layers)
● Radially​ ​symmetrical​ ​or​ ​asymmetrical
● Lack​ ​true​ ​tissues,​ ​unlike​ ​other​ ​animals
○ True​ ​tissues:​ ​groups​ ​of​ ​similar​ ​cells​ ​that​ ​act​ ​as​ ​functional​ ​units​ ​and​ ​are
isolated​ ​from​ ​other​ ​groups​ ​of​ ​cells​ ​by​ ​membranous​ ​layers
○ Allows​ ​for​ ​a​ ​process​ ​called​ ​reaggregation,​ ​where​ ​the​ ​sponge​ ​can​ ​reform​ ​even
after​ ​having​ ​been​ ​destroyed​ ​(eg
...
​ ​sea​ ​gooseberry​ ​(Pleurobrachia),​ ​warty​ ​sea​ ​walnut​ ​(Mnemiopsis​ ​leidyi),
venus​ ​girdle​ ​(Cestum​ ​veneris)
About​ ​100​ ​species,​ ​all​ ​marine
Joanna​ ​Griffith​ ​(2017)

Body​ ​plan
● Radially​ ​symmetrical
● Diploblastic
● Ciliated​ ​longitudinal​ ​rows​ ​used​ ​for​ ​propulsion
● Long,​ ​branched,​ ​contractile​ ​tentacles
○ Have​ ​sticky​ ​cells​ ​called​ ​colloblasts
■ Used​ ​to​ ​trap​ ​prey
● Many​ ​species​ ​are​ ​bioluminescent
Reproduction/development
● All​ ​species​ ​are​ ​hermaphroditic
--------------------------------------------------------------------------------------------------------------------------5:​ ​CNIDARIA
● Sister​ ​group​ ​to​ ​Eumetazoa
● Wide​ ​range​ ​of​ ​motile​ ​and​ ​sessile​ ​forms
● About​ ​10,000​ ​species,​ ​including​ ​corals,​ ​anemones​ ​and​ ​jellies
Body​ ​plan
● Has​ ​true​ ​tissues
● Diploblastic
● Radially​ ​symmetrical
● Gastrovascular​ ​cavity​ ​is​ ​also​ ​known​ ​as​ ​a​ ​coelenteron
Nutrition/digestion
● Carnivorous,​ ​predatory​ ​lifestyle
● Extensible​ ​tentacles​ ​capture​ ​prey​ ​and​ ​pass​ ​it​ ​into​ ​the​ ​gastrovascular​ ​cavity
○ Some​ ​Cnidarians​ ​can​ ​also​ ​perform​ ​extracellular​ ​digestion
● Tentacles​ ​may​ ​be​ ​armed​ ​with​ ​cnidocytes​ ​(stinging​ ​cells​ ​unique​ ​to​ ​Cnidaria)
○ Cnidae​ ​are​ ​capsule-like​ ​organelles
■ Nematocysts​ ​are​ ​specialised​ ​cnidae​ ​with​ ​stinging​ ​threads​ ​that
penetrate​ ​the​ ​body​ ​of​ ​prey
■ Other​ ​types​ ​of​ ​cnidae​ ​produce​ ​sticky/tangling​ ​threads
Nervous​ ​system/sense​ ​organs
● Muscle​ ​and​ ​nerve​ ​net
○ Bundles​ ​of​ ​microfilaments​ ​are​ ​arranged​ ​into​ ​contractile​ ​fibres​ ​in​ ​the​ ​epidermis
and​ ​gastrodermis
● No​ ​brain,​ ​simple​ ​reflex​ ​pathways
● Nerve​ ​cells​ ​interact​ ​with​ ​sensory​ ​and​ ​contractile​ ​cells​ ​to​ ​coordinate​ ​movement
Hydrozoa
● Commonly​ ​colonial​ ​organisms
○ Multiple​ ​individuals​ ​combine​ ​to​ ​make​ ​“one”​ ​organism
● Have​ ​both​ ​polyp​ ​and​ ​medusa​ ​stages,​ ​and​ ​normally​ ​alternate​ ​between​ ​them
Scyphozoa
● “True​ ​jellies”,​ ​sea​ ​nettles
● All​ ​marine
● Mostly​ ​larger​ ​jellies
○ Many​ ​are​ ​bioluminescent
Joanna​ ​Griffith​ ​(2017)

● Predominant​ ​medusa​ ​stage
Cubozoa
● Box​ ​jellies​ ​and​ ​sea​ ​wasps
○ Box-shaped​ ​medusa​ ​stage
● All​ ​marine,​ ​in​ ​the​ ​topics
● Strong​ ​swimmers
● Extremely​ ​potent​ ​venom
● Active​ ​hunters,​ ​prey​ ​mainly​ ​on​ ​fish
● Complex​ ​eyes​ ​along​ ​fringe​ ​of​ ​tentacles
Anthozoa
● “Flower​ ​animals”,​ ​such​ ​as​ ​sea​ ​anemones,​ ​most​ ​corals,​ ​sea​ ​fans
● Only​ ​occur​ ​as​ ​polyps
Myxozoa
● Parasitic​ ​class
● Unicellular,​ ​“protist”
● Highly​ ​reduced​ ​genome
● Has​ ​a​ ​polar​ ​capsule​ ​that​ ​is​ ​very​ ​similar​ ​to​ ​nematocysts
○ Evolution​ ​can​ ​simplify​ ​animal​ ​organisation
--------------------------------------------------------------------------------------------------------------------------5:​ ​ACOELA
--------------------------------------------------------------------------------------------------------------------------6:​ ​LOPHOTROCHOZOA
Bilateral​ ​symmetry
Triploblastic
Clade​ ​identified​ ​by​ ​molecular​ ​data
○ Wide​ ​range​ ​of​ ​animal​ ​body​ ​forms
■ 18​ ​phyla
■ No​ ​unique​ ​morphological​ ​features​ ​shared​ ​by​ ​all​ ​members
● Named​ ​after​ ​lophophores,​ ​crowns​ ​of​ ​ciliated​ ​tentacles,​ ​found​ ​in​ ​some​ ​members​ ​of
the​ ​clade,​ ​and​ ​trochophore​ ​larvae,​ ​which​ ​as​ ​small,​ ​translucent,​ ​spinning-top-shaped
larvae​ ​with​ ​a​ ​prominent​ ​circle​ ​of​ ​cilia,​ ​also​ ​found​ ​in​ ​some​ ​members​ ​of​ ​the​ ​clade
○ Some​ ​members​ ​of​ ​the​ ​clade​ ​lack​ ​both​ ​of​ ​these​ ​features
--------------------------------------------------------------------------------------------------------------------------●
●
●

6:​ ​PLATYHELMINTHES
●
●
●

Flatworms,​ ​flukes,​ ​and​ ​tapeworms
About​ ​20,000​ ​species
Consist​ ​of​ ​two​ ​lineages
○ Catenulida
■ Chain​ ​worms
■ Clade​ ​of​ ​100​ ​species
○ Rhabditophora
Joanna​ ​Griffith​ ​(2017)

■
■
■
■

Clade​ ​of​ ​about​ ​20,000​ ​species
Includes​ ​free-living​ ​and​ ​parasitic​ ​species
Both​ ​marine​ ​and​ ​freshwater​ ​species
Eg
...
​ ​schistosoma
○ Causes​ ​schistosomiasis​ ​(200​ ​million​ ​people​ ​infected)
○ Live​ ​in​ ​blood​ ​vessels​ ​for​ ​about​ ​40​ ​years
○ Reproduce​ ​sexually​ ​in​ ​a​ ​human​ ​host,​ ​eggs​ ​exit​ ​the​ ​host​ ​in​ ​faeces​ ​and
develop​ ​into​ ​ciliated​ ​larvae​ ​in​ ​an​ ​intermediate​ ​snail​ ​host,​ ​undergo​ ​asexual
reproduction​ ​and​ ​become​ ​motile​ ​larvae​ ​that​ ​can​ ​penetrate​ ​human​ ​skin
Cestoda
● Tapeworms
● About​ ​4000​ ​species
● All​ ​species​ ​are​ ​parasitic
○ Normally​ ​infect​ ​two​ ​host​ ​species​ ​in​ ​their​ ​lifecycles,​ ​mainly​ ​infect​ ​vertebrates
● No​ ​gastrovascular​ ​cavity,​ ​as​ ​they​ ​absorb​ ​nutrients​ ​through​ ​their​ ​skin
● Have​ ​a​ ​scolex​ ​with​ ​hooks​ ​and​ ​suckers
● Have​ ​proglottids​ ​with​ ​reproductive​ ​units
● Common​ ​cestodes​ ​in​ ​humans:
○ Beef​ ​tapeworm​ ​(Taenia​ ​saginata)
○ Pork​ ​tapeworm​ ​(Taenia​ ​solium)
○ Fish​ ​tapeworm​ ​(Diphyllobothrium)
○ Dog​ ​tapeworm​ ​(Dipylidium​ ​canium)
○ Dwarf​ ​tapeworm​ ​(Hymenolepis​ ​nana)
--------------------------------------------------------------------------------------------------------------------------7:​ ​ROTIFERA
● Multicellular,​ ​have​ ​a​ ​fixed​ ​number​ ​of​ ​highly​ ​differentiated​ ​cells
Body​ ​plan
● Pseudocoelomates
● Have​ ​a​ ​crown​ ​of​ ​cilia​ ​(a​ ​characteristic​ ​that​ ​allows​ ​them​ ​to​ ​be​ ​classified​ ​as
Lophotrochozoans)
Joanna​ ​Griffith​ ​(2017)

● Specialised​ ​organ​ ​systems
● Trunk​ ​contains​ ​visceral​ ​organs
● Cloacal​ ​bladder​ ​collects​ ​excretory/digestive​ ​waste
Nutrition/digestion
● Alimentary​ ​canal​ ​with​ ​two​ ​openings
● Pharynx​ ​(called​ ​a​ ​mastax)​ ​with​ ​intricate​ ​jaws
● The​ ​corona​ ​channels​ ​water​ ​currents​ ​into​ ​the​ ​mouth,​ ​used​ ​for​ ​feeding​ ​(and
locomotion)
● Rotifers​ ​rotate​ ​around​ ​their​ ​segmented,​ ​telescopic​ ​foot​ ​(1-4​ ​toes)​ ​to​ ​feed
Respiration/circulatory​ ​system/excretion
● Protonephridia​ ​(flame​ ​bulbs)​ ​used​ ​for​ ​osmoregulation​ ​and​ ​excretion
Reproduction/development
● Life​ ​cycles​ ​of​ ​the​ ​three​ ​Rotifera​ ​classes
○ Gonochoristic​ ​(separate​ ​male​ ​and​ ​female​ ​sexes)​ ​reproduction​ ​in​ ​Seisonidea
○ Parthenogenesis​ ​(reproduction​ ​from​ ​an​ ​ovum​ ​without​ ​fertilisation)​ ​alternating
with​ ​sexual​ ​reproduction​ ​in​ ​Monogononta
○ Obligate​ ​parthenogenesis​ ​in​ ​Bdelloidea
■ Exclusively​ ​asexual​ ​reproduction
● Nearly​ ​all​ ​other​ ​organisms​ ​have​ ​a​ ​sexual​ ​phase​ ​in​ ​their​ ​life
cycle
○ Asexual​ ​lineages​ ​often​ ​arise,​ ​but​ ​they​ ​are​ ​normally
short-lived​ ​due​ ​to​ ​a​ ​slower​ ​rate​ ​of​ ​evolution​ ​compared
to​ ​parasites​ ​and​ ​an​ ​accumulation​ ​of​ ​deleterious
mutations
○ Interactions​ ​with​ ​parasites​ ​are​ ​thought​ ​to​ ​provide
selective​ ​pressure​ ​to​ ​maintain​ ​sex
○ Bdelloidea​ ​may​ ​escape​ ​fungal​ ​pathogens​ ​by​ ​using​ ​a
dessicated​ ​resting​ ​stage​ ​(anhydrobiosis)​ ​and​ ​dispersal
--------------------------------------------------------------------------------------------------------------------------7:​ ​ECTOPROCTA
“Moss​ ​animals”
About​ ​4000​ ​species
Small​ ​(about​ ​0
...
​ ​the​ ​trembling​ ​sea​ ​mat,​ ​Victorella​ ​pavida
○ Only​ ​found​ ​in​ ​Swanpool,​ ​Falmouth
Body​ ​plan
● Lophophore​ ​(crown​ ​of​ ​ciliated​ ​tentacles)
● Coelomates
●
●
●
●
●
●
●

Joanna​ ​Griffith​ ​(2017)

Having​ ​a​ ​coelom​ ​is​ ​advantageous​ ​as​ ​it​ ​provides​ ​a​ ​hydrostatic​ ​skeleton​ ​and
allows​ ​for​ ​more​ ​efficient​ ​circulation​ ​of​ ​nutrients
○ U-shaped​ ​alimentary​ ​canal
○ No​ ​head
○ Hard​ ​exoskeleton
--------------------------------------------------------------------------------------------------------------------------○

7:​ ​BRACHIOPODA
About​ ​350​ ​species
All​ ​marine
Sessile​ ​bottom​ ​dwellers
Eg
...
​ ​clams,​ ​oysters,​ ​squids,​ ​octopuses,​ ​snails
● One​ ​of​ ​the​ ​largest​ ​phyla​ ​(about​ ​93,000​ ​species)
● Huge​ ​size​ ​range,​ ​from​ ​microscopic​ ​to​ ​18m
● Marine,​ ​freshwater,​ ​terrestrial
Body​ ​plan
● Despite​ ​external​ ​differences,​ ​they​ ​are​ ​all​ ​built​ ​with​ ​the​ ​same​ ​body​ ​plan
○ All​ ​are​ ​soft-bodied​ ​(no​ ​skeleton)​ ​and​ ​most​ ​secrete​ ​a​ ​hard​ ​shell
● Coelomates
● Mantle
○ The​ ​dorsal​ ​surface​ ​is​ ​covered​ ​by​ ​a​ ​shell​ ​that​ ​protects​ ​the​ ​internal​ ​organs
○ The​ ​mantle​ ​(epidermis)​ ​secretes​ ​the​ ​shell
●

Joanna​ ​Griffith​ ​(2017)

Epidermal​ ​secretions​ ​are​ ​continuous​ ​so​ ​the​ ​shell​ ​increases​ ​in​ ​size​ ​and
repairs​ ​itself​ ​throughout​ ​the​ ​mollusc’s​ ​life
● Retractor​ ​muscles
○ Retractor​ ​muscles​ ​are​ ​organised​ ​in​ ​pairs,​ ​and​ ​each​ ​pair​ ​is​ ​attached​ ​to​ ​the
inner​ ​surface​ ​of​ ​the​ ​shell​ ​and​ ​foot
● Mantle​ ​cavity
○ The​ ​shell​ ​and​ ​underlying​ ​mantle​ ​overhang​ ​the​ ​body,​ ​creating​ ​the​ ​mantle
cavity
○ Contains​ ​a​ ​pair​ ​of​ ​gills​ ​and​ ​a​ ​pair​ ​of​ ​nephridia
Nutrition/digestion
● Grazers,​ ​carnivores,​ ​and​ ​filter​ ​feeders
● The​ ​mouth​ ​contains​ ​a​ ​feeding​ ​organ​ ​called​ ​a​ ​radula,​ ​which​ ​allows​ ​most​ ​molluscs​ ​to
graze
Respiration/circulatory​ ​system/excretion
● Gills
○ Water​ ​enters​ ​the​ ​lower​ ​mantle​ ​cavity,​ ​passes​ ​through​ ​the​ ​gills​ ​and​ ​back,
pushed​ ​by​ ​the​ ​beating​ ​of​ ​cilia
■ Two​ ​blood​ ​vessels​ ​run​ ​over​ ​the​ ​gills​ ​and​ ​are​ ​oxygenated
● The​ ​heart
○ Open​ ​circulatory​ ​system​ ​(except​ ​in​ ​Cephalopods)
■ The​ ​coelomic​ ​cavity​ ​surrounds​ ​the​ ​heart
○ The​ ​heart​ ​consists​ ​of​ ​a​ ​pair​ ​of​ ​posterior​ ​auricles​ ​and​ ​a​ ​single​ ​anterior​ ​ventricle
● Excretory​ ​organs
○ Pair​ ​of​ ​tubular​ ​metanephridia​ ​(kidneys)
■ One​ ​end​ ​connected​ ​to​ ​the​ ​pericardial​ ​cavity,​ ​the​ ​other​ ​connected​ ​to​ ​a
nephridium
● The​ ​pericardial​ ​cavity​ ​receives​ ​waste​ ​from​ ​the​ ​heart,​ ​waste
then​ ​passes​ ​into​ ​the​ ​nephridium​ ​and​ ​urine​ ​exits​ ​through​ ​the
mantle​ ​cavity
Nervous​ ​system/sense​ ​organs
● A​ ​nerve​ ​ring​ ​loop​ ​around​ ​the​ ​oesophagus
● Pairs​ ​of​ ​nerve​ ​cords​ ​extend​ ​ventrally​ ​and​ ​dorsally
○ Ventral​ ​pair​ ​innervates​ ​the​ ​muscles​ ​of​ ​the​ ​foot
○ Dorsal​ ​pair​ ​innervates​ ​the​ ​mantle​ ​and​ ​visceral​ ​organs
● Sense​ ​organs​ ​include​ ​tentacles,​ ​eyes,​ ​touch​ ​receptors,​ ​and​ ​chemoreceptors
Reproduction/development
● Most​ ​are​ ​gonochoristic,​ ​some​ ​are​ ​hermaphroditic
● Gonads​ ​present​ ​on​ ​either​ ​side​ ​of​ ​the​ ​coelom
○ ‘Ripe’​ ​eggs​ ​and​ ​sperm​ ​break​ ​into​ ​the​ ​coelomic​ ​cavity​ ​and​ ​are​ ​transported​ ​to
the​ ​external​ ​environment​ ​through​ ​the​ ​nephridia
■ Fertilisation​ ​occurs​ ​in​ ​seawater
● Most​ ​marine​ ​and​ ​aquatic​ ​molluscs​ ​have​ ​planktonic​ ​trochophore​ ​and​ ​veliger​ ​larval
stages
Locomotion
● The​ ​epidermis​ ​is​ ​covered​ ​by​ ​cilia​ ​and​ ​mucous​ ​gland​ ​cells
○ Mucus​ ​lubricates​ ​the​ ​substratum​ ​under​ ​the​ ​foot​ ​for​ ​locomotion
■

Joanna​ ​Griffith​ ​(2017)

Formation​ ​of​ ​pearls
● Pearls​ ​form​ ​inside​ ​the​ ​shells​ ​of​ ​certain​ ​molluscs​ ​as​ ​a​ ​defense​ ​mechanism​ ​against​ ​a
potentially​ ​threatening​ ​irritant​ ​(eg
...
​ ​snails,​ ​slugs,​ ​limpets,​ ​whelks,​ ​conch,​ ​sea​ ​hares,​ ​periwinkles,​ ​sea​ ​butterflies
● 75%​ ​of​ ​all​ ​mollusc​ ​species​ ​are​ ​gastropods
Joanna​ ​Griffith​ ​(2017)

●
●

●

●

The​ ​only​ ​molluscs​ ​to​ ​have​ ​colonised​ ​land
Body​ ​plan
○ Shell​ ​morphology
■ Have​ ​a​ ​heavy,​ ​univalve,​ ​coiled​ ​shell​ ​(coils​ ​may​ ​reduce​ ​or​ ​disappear​ ​in
adult​ ​stages)
■ Planispiral​ ​to​ ​asymmetrical​ ​shell​ ​coiling
● Ancestral​ ​planispiral​ ​shells​ ​were​ ​huge​ ​and​ ​heavy,​ ​leading​ ​to
the​ ​development​ ​of​ ​asymmetrical​ ​coiling
■ Shell​ ​consists​ ​of​ ​four​ ​layers
● Outer​ ​layer​ ​is​ ​conchiolin​ ​or​ ​conchin
● Inner​ ​layers​ ​consist​ ​of​ ​calcium​ ​carbonate
■ Shell​ ​colours​ ​result​ ​from​ ​pigment​ ​in​ ​the​ ​calcareous​ ​layers​ ​of​ ​the​ ​shell
■ Retractor​ ​muscles​ ​close​ ​the​ ​shell​ ​and​ ​the​ ​operculum​ ​acts​ ​as​ ​a​ ​door​ ​or
lid
○ The​ ​anus​ ​and​ ​the​ ​nephridiopore​ ​open​ ​near​ ​the​ ​pneumostome​ ​(lung​ ​opening)
○ Torsion
■ Process​ ​of​ ​moving​ ​the​ ​mantle​ ​cavity​ ​to​ ​the​ ​front​ ​of​ ​the​ ​body
■ Pre-torsion:​ ​anterior​ ​head​ ​and​ ​posterior​ ​anus
■ During​ ​torsion​ ​(during​ ​the​ ​veliger​ ​larval​ ​stage),​ ​the​ ​visceral​ ​mass
twists​ ​180°
■ Only​ ​occurs​ ​in​ ​gastropods
■ Post-torsion:​ ​left​ ​gill,​ ​kidney,​ ​and​ ​heart​ ​auricle​ ​are​ ​all​ ​on​ ​the​ ​right-hand
side​ ​and​ ​vice-versa
● Modern​ ​gastropods​ ​have​ ​lost​ ​their​ ​right​ ​gill,​ ​kidney,​ ​and​ ​heart
auricle
● Mantle​ ​cavity​ ​and​ ​anus​ ​open​ ​above​ ​the​ ​head​ ​and​ ​mouth
■ Advantages​ ​(heavily​ ​debated)
● The​ ​head​ ​can​ ​enter​ ​the​ ​shell​ ​first,​ ​then​ ​the​ ​foot​ ​with​ ​the
operculum​ ​to​ ​close​ ​the​ ​shell
● Allows​ ​entry​ ​of​ ​clean​ ​water​ ​onto​ ​gills
● Inhalant​ ​current​ ​can​ ​be​ ​sampled​ ​by​ ​osphradia​ ​sensory​ ​organs
in​ ​the​ ​mantle
■ Some​ ​nudibranchs​ ​undergo​ ​90°​ ​detorsion​ ​as​ ​adults,​ ​likely​ ​for
sanitation​ ​issues
nutrition/digestion
○ Highly​ ​varied​ ​diets
○ Most​ ​are​ ​herbivorous​ ​(grazers/browsers)
○ Ciliary​ ​feeders​ ​(eg
...
​ ​the​ ​textile​ ​cone​ ​shell​ ​(Conus​ ​textile)​ ​uses​ ​its​ ​radula​ ​as​ ​a
venomous​ ​harpoon
respiration/circulatory​ ​system/excretion
○ Respiration​ ​via​ ​gills/skin
■ Terrestrial​ ​snails​ ​and​ ​slugs​ ​have​ ​a​ ​pallial​ ​lung
○ Well-developed​ ​circulatory​ ​system
Joanna​ ​Griffith​ ​(2017)

Nervous​ ​system/sense​ ​organs
○ Well-developed​ ​nervous​ ​system
● reproduction/development
○ Gonochoristic​ ​and​ ​hermaphroditic​ ​species
■ Elaborate​ ​courtship​ ​rituals,​ ​eg
...
​ ​copulation​ ​of​ ​shelled​ ​Helicidea
■ Vagina​ ​contains​ ​an​ ​oval​ ​dart​ ​sac​ ​which​ ​secretes​ ​a​ ​calcareous​ ​spicule
● When​ ​the​ ​snails​ ​are​ ​intertwined,​ ​one​ ​pushes​ ​the​ ​dart​ ​into​ ​the
body​ ​wall​ ​of​ ​the​ ​other
● Subclasses
○ Prosobranchia
■ Eg
...
​ ​sea​ ​hares​ ​(vestigial​ ​shell),​ ​sea​ ​slugs,​ ​nudibranchs​ ​(have​ ​cerata),
canoe​ ​shells
○ Pulmonata
■ Eg
...
​ ​mussels,​ ​clams,​ ​scallops,​ ​oysters
● Most​ ​marine,​ ​a​ ​few​ ​brackish​ ​water​ ​and​ ​freshwater
● Diverse​ ​size​ ​range,​ ​from​ ​about​ ​2mm​ ​to​ ​1
...
​ ​by​ ​razor​ ​clams​ ​to​ ​burrow
■ Foot​ ​can​ ​be​ ​inflated​ ​to​ ​anchor​ ​the​ ​bivalve​ ​into​ ​sediment
○ Eg
...
​ ​octopus,​ ​squid,​ ​cuttlefish,​ ​nautilus
○

Joanna​ ​Griffith​ ​(2017)

●
●

●
●

●

All​ ​marine,​ ​found​ ​in​ ​all​ ​oceans
Normally​ ​2-70cm,​ ​but​ ​the​ ​giant​ ​squid​ ​(Architeuthis​ ​dux)​ ​can​ ​grow​ ​to​ ​up​ ​to​ ​18m
○ The​ ​colossal​ ​squid​ ​(Mesonychoteuthis​ ​hamiltoni)​ ​is​ ​the​ ​heaviest​ ​known
invertebrate,​ ​at​ ​500kg
Ammonites​ ​were​ ​dominant​ ​in​ ​the​ ​Mesozoic​ ​era​ ​until​ ​their​ ​Cretaceous​ ​extinction
Body​ ​plan
○ Tentacles
■ Nautilus​ ​have​ ​38​ ​tentacles,​ ​no​ ​suckers
■ Squid​ ​and​ ​cuttlefish​ ​have​ ​4​ ​pairs​ ​of​ ​arms​ ​and​ ​1​ ​pair​ ​of​ ​tentacles
● The​ ​inner​ ​arm​ ​is​ ​flattened​ ​and​ ​covered​ ​with​ ​stalked​ ​suckers
that​ ​are​ ​horny​ ​and​ ​toothed
■ Octopods​ ​have​ ​8​ ​arms​ ​and​ ​suckers
● Self-recognition​ ​mechanism​ ​between​ ​skin​ ​and​ ​suckers
prevents​ ​octopus​ ​arms​ ​from​ ​interfering​ ​with​ ​each​ ​other
○ “Spaghetti​ ​holding”​ ​behaviour
○ Form​ ​and​ ​function​ ​of​ ​the​ ​nautilus’​ ​shell
■ All​ ​cephalopods​ ​have​ ​undergone​ ​a​ ​progressive​ ​loss​ ​of​ ​shell,​ ​except
nautilus,​ ​which​ ​still​ ​have​ ​an​ ​external​ ​shell
■ Nautilus​ ​shells​ ​are​ ​divided​ ​by​ ​transverse​ ​septa​ ​into​ ​internal​ ​chambers
● The​ ​septum​ ​is​ ​perforated​ ​in​ ​the​ ​middle​ ​by​ ​a​ ​cord​ ​of​ ​tissue
called​ ​the​ ​siphuncle
○ The​ ​siphuncle​ ​secretes​ ​gas​ ​into​ ​the​ ​empty​ ​chambers
and​ ​makes​ ​the​ ​shell​ ​buoyant
■ Limitations
● The​ ​nautilus​ ​can​ ​only​ ​reach​ ​certain​ ​depths​ ​before​ ​pressure
causes​ ​the​ ​shell​ ​to​ ​implode
● Not​ ​aquadynamic,​ ​creates​ ​drag​ ​through​ ​the​ ​water
■ The​ ​ancestor​ ​of​ ​all​ ​cephalopods​ ​had​ ​a​ ​shell
● Cuttlefish​ ​and​ ​squid​ ​have​ ​internal​ ​shells
● Octopods​ ​have​ ​no​ ​shells
● Nautiluses​ ​are​ ​the​ ​only​ ​cephalopods​ ​that​ ​have​ ​maintained​ ​an
external​ ​shell
○ Colour​ ​change
■ Chromatophores​ ​are​ ​present​ ​in​ ​the​ ​integument​ ​(protective​ ​outer​ ​layer)
● Small​ ​muscles​ ​are​ ​attached​ ​to​ ​the​ ​edges​ ​of​ ​the
chromatophores
● Different​ ​cephalopod​ ​species​ ​have​ ​chromatophores​ ​of​ ​different
colours
● The​ ​effect​ ​is​ ​enhanced​ ​by​ ​iridocytes​ ​or​ ​reflector​ ​cells
■ Some​ ​colour​ ​changes​ ​are​ ​associated​ ​with​ ​behaviour
● Camouflage
● Squid​ ​and​ ​octopods​ ​may​ ​darken​ ​when​ ​they​ ​are​ ​alarmed
● Colour​ ​displays​ ​associated​ ​with​ ​courtship
nutrition/digestion
○ All​ ​cephalopods​ ​are​ ​active​ ​predators,​ ​hunt​ ​a​ ​wide​ ​range​ ​of​ ​prey
○ Prey​ ​are​ ​captured​ ​using​ ​tentacles​ ​or​ ​arms
Joanna​ ​Griffith​ ​(2017)

Radula​ ​is​ ​present,​ ​but​ ​the​ ​jaws​ ​in​ ​the​ ​buccal​ ​cavity​ ​are​ ​more​ ​important
■ Tissue​ ​is​ ​pulled​ ​into​ ​the​ ​buccal​ ​cavity​ ​by​ ​the​ ​radula,​ ​and​ ​a​ ​pair​ ​of
salivary​ ​glands​ ​empty​ ​into​ ​the​ ​cavity
● Octopods​ ​also​ ​secretes​ ​poison​ ​and​ ​enzymes​ ​into​ ​prey
○ Cephalopod​ ​diets​ ​depend​ ​on​ ​their​ ​habitats
■ Squid​ ​feed​ ​on​ ​fish,​ ​crustaceans,​ ​and​ ​other​ ​squid
■ Cuttlefish​ ​swim​ ​along​ ​the​ ​bottom​ ​and​ ​feed​ ​on​ ​invertebrates​ ​such​ ​as
shrimp​ ​and​ ​crabs
■ Octopods​ ​tend​ ​to​ ​live​ ​in​ ​dens,​ ​so​ ​they​ ​can​ ​search​ ​for​ ​food​ ​or​ ​lie​ ​in​ ​wait
● They​ ​can​ ​capture​ ​clams,​ ​snails,​ ​crustaceans,​ ​and​ ​fish,​ ​and
paralyze​ ​them
respiration/circulatory​ ​system/excretion
○ Cephalopods​ ​are​ ​the​ ​only​ ​molluscs​ ​with​ ​a​ ​closed​ ​circulatory​ ​system
■ Blood​ ​remains​ ​separate​ ​from​ ​the​ ​fluid​ ​in​ ​the​ ​body​ ​cavity
Nervous​ ​system/sense​ ​organs
○ In​ ​cephalopods,​ ​the​ ​ganglia​ ​are​ ​concentrated​ ​and​ ​fused​ ​to​ ​form​ ​the​ ​brain
■ A​ ​cartilaginous​ ​cranium​ ​protects​ ​the​ ​brain
■ Separate​ ​regions​ ​of​ ​the​ ​brain​ ​control​ ​different​ ​areas
● Eg
...
​ ​Lumbricus​ ​terrestris​ ​(common​ ​earthworm)
○ Eg
...
​ ​Arenicola​ ​marina​ ​(lugworm)
○ Eg
...
​ ​Spirobranchus​ ​giganteus​ ​(Christmas​ ​tree​ ​worm)
○ Eg
...
​ ​Florida​ ​mudflats
○ Re-emergence​ ​in​ ​medicinal​ ​use
● Traditionally​ ​divided​ ​into​ ​7​ ​classes​ ​and​ ​subclasses
○ Phylogenetic​ ​analysis​ ​indicates​ ​most​ ​of​ ​these​ ​are​ ​either​ ​paraphyletic​ ​or
polyphyletic
Body​ ​plan
● Metameric​ ​(segmented)
○ Metameric​ ​structures​ ​confined​ ​to​ ​the​ ​trunk
○ The​ ​prostomium​ ​(head),​ ​peristomium​ ​(behind​ ​prostomium)​ ​and​ ​pygidium
(terminal​ ​part)​ ​are​ ​not​ ​segments
○ The​ ​formation​ ​of​ ​new​ ​segments​ ​takes​ ​place​ ​just​ ​before​ ​the​ ​pygidium
● Coelomates
○ The​ ​coelomic​ ​fluid​ ​functions​ ​as​ ​a​ ​hydrostatic​ ​skeleton
Locomotion
● Movement​ ​by​ ​peristalsis
○ Two​ ​sets​ ​of​ ​muscles,​ ​longitudinal​ ​and​ ​circular
○ Widening​ ​and​ ​elongation​ ​can​ ​be​ ​restricted​ ​to​ ​certain​ ​segments
○ Waves​ ​of​ ​peristaltic​ ​contraction​ ​pass​ ​down​ ​the​ ​length​ ​of​ ​the​ ​body​ ​and​ ​cause
elongation​ ​and​ ​shortening​ ​in​ ​each​ ​segment
○ Chitinous,​ ​paired,​ ​lateral​ ​bristles​ ​(chaetae)​ ​increase​ ​traction​ ​with​ ​the​ ​substrate
Polychaetes
● Largest​ ​class,​ ​about​ ​10,000​ ​species
● Most​ ​range​ ​from​ ​5-10cm
● Mostly​ ​marine
● Wide​ ​range​ ​of​ ​lifestyles
○ Tube​ ​dwelling,​ ​burrowing,​ ​pelagic
● Body​ ​plan
○ Segmented​ ​worms​ ​with​ ​“legs”​ ​(chaetae/parapodia)
●

Joanna​ ​Griffith​ ​(2017)

●

●

●

■ Have​ ​many​ ​chaetae
○ Prostomium
■ Well​ ​differentiated
■ Specialised​ ​sense​ ​organs
■ Chitinous​ ​jaws​ ​(light​ ​and​ ​strong)
■ Bears​ ​eyes,​ ​antennae,​ ​and​ ​palps
■ Sometimes​ ​retractile
○ Peristomium
■ Surrounds​ ​mouth
○ Pygidium
■ Carries​ ​the​ ​anus
○ Have​ ​characteristic​ ​parapodia​ ​topped​ ​with​ ​chaetae
■ Paired,​ ​fleshy​ ​appendages​ ​that​ ​extend​ ​from​ ​the​ ​body​ ​segments
■ Sweep​ ​ground/water​ ​for​ ​locomotion
■ Can​ ​be​ ​converted​ ​into​ ​respiratory​ ​organs​ ​in​ ​larger​ ​worms
Nervous​ ​system/sense​ ​organs
○ Brain
■ Lies​ ​in​ ​the​ ​prostomium
■ Supplies​ ​nerves​ ​to​ ​the​ ​palps,​ ​antennae​ ​and​ ​eyes
■ The​ ​ventral​ ​nerve​ ​cord​ ​is​ ​doubled​ ​through​ ​the​ ​segments,​ ​although​ ​the
two​ ​cords​ ​are​ ​often​ ​fused
■ Presence​ ​of​ ​giant​ ​axons​ ​(1
...
​ ​in​ ​peacock
worms
● Increases​ ​reaction​ ​time​ ​by​ ​40x
○ Retinal​ ​cup​ ​eye
■ Detects​ ​light​ ​intensity​ ​and​ ​source
○ Nuchal​ ​organs​ ​on​ ​head​ ​region
■ Detect​ ​food
○ Statocytes
■ Found​ ​in​ ​burrowers
■ Detect​ ​changes​ ​in​ ​orientation
Reproduction
○ Asexual​ ​reproduction​ ​occurs,​ ​but​ ​sexual​ ​reproduction​ ​is​ ​more​ ​common
○ Most​ ​species​ ​are​ ​gonochoristic
○ No​ ​permanent​ ​sex​ ​organs
■ When​ ​the​ ​worm​ ​is​ ​mature,​ ​it​ ​is​ ​packed​ ​with​ ​sperm​ ​and​ ​eggs
○ External​ ​fertilisation
○ Eg
...
​ ​sea​ ​mouse
● Chaetae​ ​scatter​ ​light,​ ​creating​ ​patterns​ ​of​ ​colours
■ Live​ ​beneath​ ​stones,​ ​in​ ​coral​ ​crevices,​ ​and​ ​in​ ​algae
○ Pelagic​ ​dwellers
Joanna​ ​Griffith​ ​(2017)

○

○

■ Similar​ ​to​ ​surface​ ​dwellers,​ ​but​ ​transparent
Burrowers
■ Occupy​ ​vertical​ ​or​ ​U-shaped​ ​burrows
■ Prostomial​ ​sensory​ ​appendages​ ​are​ ​generally​ ​absent
Tubicolous
■ Live​ ​in​ ​tubes,​ ​tubes​ ​may​ ​be​ ​composed​ ​of​ ​secreted​ ​material

Oligochaetes
● Eg
...
​ ​crown​ ​of​ ​thorns),​ ​oyster​ ​beds
(eg
...
​ ​orange​ ​sea​ ​cucumber
● respiration/circulatory​ ​system/excretion
○ Unique​ ​respiratory​ ​tree
■ Branching​ ​tube​ ​inside​ ​anus​ ​for​ ​gas​ ​exchange
● Trunks​ ​of​ ​trees​ ​merge​ ​with​ ​the​ ​cloaca
● Water​ ​circulates​ ​through​ ​the​ ​tubules​ ​by​ ​the​ ​pumping​ ​action​ ​of
the​ ​cloaca​ ​and​ ​respiratory​ ​tree
● Gases​ ​are​ ​exchanged​ ​with​ ​the​ ​coelomic​ ​fluid
● Defence
○ Cuvierian​ ​tubules​ ​discharge
■ Long,​ ​sticky,​ ​toxic​ ​threads
■ Tubes​ ​of​ ​Cuvier​ ​regenerate
○ The​ ​most​ ​extreme​ ​defence​ ​mechanism​ ​is​ ​evisceration
■ Discharge​ ​of​ ​digestive​ ​tract,​ ​respiratory​ ​tract,​ ​and​ ​gonads
■ May​ ​also​ ​be​ ​used​ ​to​ ​purge​ ​the​ ​gut​ ​of​ ​waste
Crinoidea
● Primitive​ ​sessile​ ​class​ ​(similar​ ​to​ ​500​ ​million​ ​year​ ​old​ ​fossils)
● Sea​ ​lilies,​ ​feather​ ​stars
● Pentaradial​ ​symmetry
○ Five​ ​or​ ​more​ ​flexible​ ​arms
● U-shaped​ ​gut,​ ​anus​ ​next​ ​to​ ​mouth
● No​ ​madreporite,​ ​pedicellariae,​ ​and​ ​spines
● Suspension​ ​feeders
Concentricycloidea
● Primitive​ ​sessile​ ​class
● Sea​ ​daisies
● First​ ​discovered​ ​in​ ​1986​ ​in​ ​New​ ​Zealand
○ Three​ ​species​ ​in​ ​the​ ​Bahamas​ ​and​ ​North​ ​Pacific
○ Relationships​ ​to​ ​other​ ​Echinoderms​ ​is​ ​unclear
● No​ ​arms
● Pentaradial​ ​symmetry
● Tube​ ​feet​ ​on​ ​the​ ​periphery​ ​of​ ​the​ ​disc
● No​ ​anus,​ ​no​ ​intestine
--------------------------------------------------------------------------------------------------------------------------Joanna​ ​Griffith​ ​(2017)

13,15,16,17,18,&19:​ ​ARTHROPODA
Most​ ​invertebrate​ ​species​ ​are​ ​arthropods
Ecdysozoans
○ Animals​ ​that​ ​shed​ ​an​ ​external​ ​‘coat’​ ​(cuticle)​ ​when​ ​they​ ​moult​ ​(ecdysis)
○ Most​ ​successful​ ​and​ ​abundant​ ​animal​ ​group
Body​ ​plan
● All​ ​arthropods​ ​have​ ​a​ ​fairly​ ​similar​ ​body​ ​plan
● Exoskeleton
○ Chitinous​ ​exoskeleton​ ​or​ ​cuticle
■ Cuticle​ ​is​ ​soft​ ​until​ ​it​ ​is​ ​sclerotised
■ Cuticle​ ​is​ ​divided​ ​into​ ​several​ ​plates
● Plates​ ​are​ ​connected​ ​by​ ​articular​ ​membranes
○ Many​ ​arthropods​ ​also​ ​have​ ​articular​ ​condyles​ ​and
sockets​ ​(eg
...
​ ​in​ ​arachnids)
● Malpighian​ ​tubules
○ Involved​ ​in​ ​the​ ​removal​ ​of​ ​nitrogenous​ ​waste​ ​from​ ​the​ ​blood​ ​in​ ​terrestrial​ ​taxa
○ Lie​ ​in​ ​hemolymph​ ​alongside​ ​the​ ​gut​ ​in​ ​arachnids​ ​and​ ​hexapods
○ Secrete​ ​uric​ ​acid​ ​into​ ​the​ ​hindgut
● Aquatic​ ​taxa​ ​use​ ​saccate​ ​nephridia​ ​that​ ​secrete​ ​ammonia,​ ​typically​ ​across​ ​the​ ​gills
○ Ammonia​ ​is​ ​toxic​ ​and​ ​must​ ​be​ ​diluted​ ​in​ ​water​ ​during​ ​excretion
■ Terrestrial​ ​taxa​ ​secrete​ ​uric​ ​acid,​ ​which​ ​is​ ​less​ ​toxic​ ​and​ ​therefore
does​ ​not​ ​require​ ​as​ ​much​ ​water
Nervous​ ​system/sense​ ​organs
● Like​ ​other​ ​animals,​ ​the​ ​basic​ ​units​ ​of​ ​a​ ​neuron​ ​are​ ​the​ ​dendrite​ ​and​ ​axon
○ Neurons​ ​are​ ​interconnected​ ​to​ ​form​ ​nerve​ ​centres​ ​(ganglia)
● Brain
○ Anterior​ ​protocerebrum
○ Medium​ ​deutocerebrum
○ Posterior​ ​tritocerebrum
● Arthropod​ ​nervous​ ​systems​ ​are​ ​a​ ​major​ ​target​ ​for​ ​insecticides
○ DDT​ ​and​ ​pyrethroid:​ ​target​ ​sodium​ ​channels​ ​in​ ​axons,​ ​blocked​ ​channels
cause​ ​paralysis
○ Organophosphates:​ ​target​ ​acetylcholinesterase,​ ​the​ ​deactivated​ ​enzyme
means​ ​that​ ​neurotransmitters​ ​are​ ​not​ ​removed​ ​from​ ​the​ ​synaptic​ ​cleft
○ Neonicotinoids:​ ​target​ ​acetylcholine​ ​receptors,​ ​blocking​ ​the​ ​receptors​ ​means
that​ ​the​ ​neurotransmitter​ ​cannot​ ​function
● Sense​ ​organs
○ Having​ ​an​ ​exoskeleton​ ​can​ ​make​ ​it​ ​more​ ​difficult​ ​to​ ​sense​ ​the​ ​environment
○ Sensilla
■ Have​ ​chemo-​ ​or​ ​mechano-receptors​ ​that​ ​detect​ ​external​ ​stimuli
○ Eyes
■ Vary​ ​in​ ​complexity
● Can​ ​be​ ​simple​ ​eyes​ ​with​ ​a​ ​few​ ​photoreceptors​ ​or​ ​complex
eyes​ ​with​ ​thousands​ ​of​ ​photoreceptors
■ Images​ ​produced​ ​are​ ​crude
■ Poor​ ​distance​ ​vision
■ High​ ​flicker-fusion​ ​rate
■ Eg
...
​ ​pheromones​ ​in​ ​moths​ ​(fluffy​ ​antennae)
Locomotion
● Musculature
○ Striated​ ​muscle​ ​bundles
○ Not​ ​attached​ ​directly​ ​to​ ​the​ ​hard​ ​part​ ​of​ ​the​ ​exoskeleton,​ ​instead​ ​attached​ ​to
the​ ​epidermis,​ ​which​ ​is​ ​then​ ​attached​ ​to​ ​the​ ​hard​ ​cuticle​ ​by​ ​microtubules
■ Allows​ ​the​ ​organism​ ​to​ ​still​ ​use​ ​its​ ​muscles​ ​to​ ​escape​ ​predators​ ​after
moulting
○ Specialised​ ​for​ ​rapid​ ​movement
● Movement
○ The​ ​muscles​ ​and​ ​skeleton​ ​work​ ​together
○ Typically,​ ​muscles​ ​work​ ​in​ ​pairs​ ​(extensors​ ​and​ ​flexors)
○ Increase​ ​in​ ​blood​ ​pressure​ ​can​ ​extend​ ​plates​ ​in​ ​the​ ​thorax/abdomen
○ Generally,​ ​jointed​ ​appendages​ ​are​ ​used
○ Speed​ ​of​ ​movement​ ​is​ ​dependent​ ​on​ ​appendage​ ​length
○ Gait
■ Wave​ ​of​ ​leg​ ​movement
● Legs​ ​on​ ​opposite​ ​sides​ ​of​ ​the​ ​body​ ​alternate
● Undulation
○ Efficient​ ​locomotor-skeletal​ ​system
■ Tubular​ ​structure​ ​resists​ ​bending
■ But,​ ​if​ ​the​ ​animal​ ​were​ ​to​ ​grow​ ​too​ ​large,​ ​the​ ​soft​ ​exoskeleton​ ​would
buckle​ ​after​ ​moulting
Key​ ​adaptations​ ​for​ ​life​ ​on​ ​land
● Hard​ ​exoskeleton​ ​with​ ​waxy​ ​epicuticle
○ Small​ ​organisms​ ​have​ ​a​ ​large​ ​surface​ ​area​ ​to​ ​volume,​ ​so​ ​the​ ​exoskeleton
helps​ ​to​ ​trap​ ​water
● Jointed​ ​limbs​ ​with​ ​opposing​ ​muscles
● Efficient​ ​nitrogenous​ ​waste​ ​excretion​ ​via​ ​uric​ ​acid
● Gas​ ​exchange​ ​systems​ ​that​ ​can​ ​function​ ​in​ ​air​ ​(trachea​ ​or​ ​book​ ​lungs)
● Hindgut​ ​to​ ​recover​ ​water​ ​from​ ​food
● Internal​ ​fertilisation
● Pre-adaptation:​ ​a​ ​shift​ ​in​ ​the​ ​function​ ​of​ ​a​ ​trait​ ​during​ ​evolution
○ A​ ​trait​ ​may​ ​evolve​ ​because​ ​it​ ​serves​ ​one​ ​particular​ ​function,​ ​but​ ​subsequently
it​ ​may​ ​come​ ​to​ ​serve​ ​another
Trilobitomorpha
Joanna​ ​Griffith​ ​(2017)

Antennae,​ ​legs
10​ ​orders,​ ​150+​ ​families,​ ​5,000​ ​genera,​ ​20,000​ ​described​ ​species
○ Useful​ ​for​ ​dating​ ​rocks
● Trilobite​ ​means​ ​‘three-lobed’
○ Describes​ ​body​ ​segments
● Modern​ ​arthropods
○ The​ ​earliest​ ​fossils​ ​with​ ​an​ ​arthropod-type​ ​body​ ​plan​ ​are​ ​from​ ​the​ ​Cambrian
explosion
■ Body​ ​segments​ ​were​ ​equal​ ​to​ ​each​ ​other
● Through​ ​evolution,​ ​the​ ​segments​ ​became​ ​specialised
Chelicerata
● Body​ ​plan
○ Clawlike​ ​appendages​ ​called​ ​chelicerae
○ Cephalothorax​ ​and​ ​abdomen
○ No​ ​antennae
○ Simple​ ​eyes​ ​(single​ ​lens)
○ Chelicerae,​ ​pedipalps,​ ​legs
● Eurypterids
○ Sea​ ​scorpions
○ Extinct​ ​in​ ​Permian​ ​period
■ Ancestors​ ​of​ ​arachnida?
○ Top​ ​marine​ ​predators​ ​(1-2ft​ ​long)
● Xiphosura
○ Most​ ​are​ ​extinct,​ ​only​ ​horseshoe​ ​crabs​ ​remain
■ ‘Living​ ​fossils’
■ Characteristic​ ​trisegmented​ ​chelicerae​ ​on​ ​either​ ​side​ ​of​ ​the​ ​upper​ ​lip
■ 5​ ​pairs​ ​of​ ​walking​ ​legs,​ ​posterior​ ​to​ ​the​ ​chelicerae
● Bases​ ​of​ ​legs​ ​have​ ​gnathobases,​ ​which​ ​aid​ ​in​ ​food​ ​processing
■ Blue​ ​blood
● Contains​ ​copper​ ​(hemocyanin)​ ​rather​ ​than​ ​iron
● Arachnida
○ Includes​ ​scorpions,​ ​spiders,​ ​harvestmen,​ ​mites,​ ​and​ ​ticks
○ Body​ ​plan
■ Probably​ ​evolved​ ​from​ ​aquatic​ ​environments
● Epicuticle​ ​became​ ​waxy​ ​to​ ​reduce​ ​water​ ​loss
● Gills​ ​became​ ​modified​ ​for​ ​use​ ​in​ ​air​ ​(book​ ​lungs​ ​and​ ​trachea)
● Appendages​ ​became​ ​better​ ​adapted​ ​for​ ​terrestrial​ ​locomotion
■ Poison​ ​and​ ​silk​ ​glands
○ nutrition/digestion
■ Most​ ​arachnids​ ​are​ ​carnivorous
■ Prey​ ​are​ ​captured​ ​and​ ​killed​ ​using​ ​the​ ​chelicerae
■ Food​ ​is​ ​rapidly​ ​digested​ ​externally
● Food​ ​‘broth’​ ​is​ ​sucked​ ​up​ ​into​ ​the​ ​prebuccal​ ​cavity
○ respiration/circulatory​ ​system/excretion
■ Book​ ​lungs​ ​(invaginations)
● The​ ​book​ ​lungs​ ​in​ ​Xiphosura​ ​are​ ​exvaginations
●
●

Joanna​ ​Griffith​ ​(2017)

Trachaea​ ​and​ ​malpighian​ ​tubules​ ​evolved​ ​independently​ ​twice​ ​in
arthropods
Order​ ​Scorpiones
■ Among​ ​the​ ​oldest​ ​terrestrial​ ​arthropods
■ Generally​ ​nocturnal
● Fluorescent​ ​under​ ​UV​ ​light
■ Relatively​ ​large,​ ​can​ ​be​ ​between​ ​3-9cm
■ Body​ ​plan
● Body​ ​consists​ ​of​ ​a​ ​cephalothorax​ ​covered​ ​by​ ​a​ ​carapace,​ ​a
long​ ​abdomen,​ ​and​ ​a​ ​sting
○ In​ ​the​ ​middle​ ​of​ ​the​ ​carapace​ ​are​ ​a​ ​pair​ ​of​ ​large​ ​median
eyes
● Small​ ​anterior​ ​chelicerae​ ​and​ ​enlarged​ ​pedipalps​ ​that​ ​form
pincers
● The​ ​abdomen​ ​has​ ​7​ ​pre-abdomen​ ​segments​ ​and​ ​5
post-abdomen​ ​narrow​ ​segments
● An​ ​opercular​ ​plate​ ​covers​ ​the​ ​genital​ ​opening
● Posterior​ ​to​ ​the​ ​opercular​ ​plate​ ​are​ ​sensory​ ​pectine​ ​near​ ​the
ventral​ ​midline
■ nutrition/digestion
● Most​ ​species​ ​are​ ​sit​ ​and​ ​wait​ ​predators
● Use​ ​their​ ​stings​ ​and/or​ ​pedipalps​ ​(pincers)
■ reproduction/development
● Males​ ​initiate​ ​courtship
○ Courtship​ ​may​ ​take​ ​minutes​ ​or​ ​hours
● Male​ ​deposits​ ​a​ ​spermatophore​ ​on​ ​the​ ​ground​ ​and​ ​positions
the​ ​female​ ​over​ ​it
● All​ ​scorpions​ ​brood​ ​eggs​ ​in​ ​the​ ​female​ ​reproductive​ ​tract
○ Aplacental​ ​viviparous​ ​species
● Development​ ​takes​ ​place​ ​in​ ​the​ ​ovaries
● After​ ​up​ ​to​ ​a​ ​year,​ ​1-90​ ​offspring​ ​are​ ​produced
Order​ ​Thelyphonida
■ Whip​ ​scorpions
■ Eg
...
​ ​compound​ ​eyes,​ ​colour​ ​vision​ ​(jumping
spiders)
■ Silk
● Each​ ​spinneret​ ​has​ ​many​ ​openings​ ​from​ ​the​ ​silk​ ​gland
● Silk​ ​is​ ​a​ ​protein,​ ​secreted​ ​as​ ​a​ ​liquid
● Many​ ​uses​ ​for​ ​silk,​ ​eg
...
25-0
...
​ ​Eriophyidae
○ Family​ ​of​ ​200+​ ​genera​ ​of​ ​mites
○ Worm-like,​ ​only​ ​have​ ​2​ ​pairs​ ​of​ ​legs
○ Chelicerae​ ​are​ ​modified​ ​into​ ​needle-like​ ​stylets​ ​to
pierce​ ​and​ ​suck​ ​out​ ​plant​ ​cell​ ​contents
○ Eg
...
​ ​Varroa​ ​destructor
○ Parasitic​ ​mite​ ​that​ ​attacks​ ​honey​ ​bees​ ​and​ ​causes​ ​the
disease​ ​Varroatosis
■ Female​ ​mites​ ​enter​ ​the​ ​honey​ ​bee​ ​brood​ ​cells
and​ ​lay​ ​eggs​ ​on​ ​the​ ​larvae
● When​ ​the​ ​larvae​ ​hatch,​ ​they​ ​suck​ ​the
bee​ ​larvae​ ​hemolymph,​ ​weakening​ ​them
● Eg
...
​ ​Ixodes
○ Lyme​ ​disease,​ ​carried​ ​by​ ​a​ ​bacterium​ ​belonging​ ​to​ ​the
genus​ ​Borrelia
■ Carried​ ​by​ ​ticks​ ​in​ ​the​ ​Ixodes​ ​genus
● Tick​ ​has​ ​a​ ​2-year​ ​lifestyle
● As​ ​it​ ​feeds,​ ​it​ ​transmits​ ​the​ ​disease
● Eg
...
​ ​Illacme​ ​plenipes​ ​has​ ​750​ ​legs
● respiration/circulatory​ ​system/excretion
○ Gas​ ​exchange​ ​is​ ​through​ ​a​ ​tracheal​ ​system
○ Spiracles​ ​are​ ​always​ ​open,​ ​leads​ ​to​ ​water​ ​loss
○ The​ ​heart​ ​is​ ​a​ ​dorsal​ ​tube​ ​that​ ​extends​ ​through​ ​the​ ​body
○ Have​ ​hemocyanin​ ​(copper​ ​instead​ ​of​ ​iron)
● Nervous​ ​system/sense​ ​organs
○ Nervous​ ​system​ ​isn’t​ ​centralised
● Chilopoda
○ Centipedes
○ Most​ ​North​ ​American​ ​and​ ​European​ ​species​ ​are​ ​3-6cm​ ​long,​ ​tropical​ ​species
can​ ​be​ ​up​ ​to​ ​30cm​ ​long​ ​(Scolopendra​ ​gigantea)
Joanna​ ​Griffith​ ​(2017)

Temperate​ ​zone​ ​centipedes​ ​tend​ ​to​ ​be​ ​reddish​ ​brown,​ ​but​ ​tropical​ ​species
can​ ​be​ ​any​ ​combination​ ​of​ ​colours
○ Body​ ​plan
■ Antennae​ ​on​ ​the​ ​front​ ​margins
■ Mandibles​ ​bear​ ​teeth​ ​and​ ​a​ ​fringe​ ​of​ ​setae
■ Covering​ ​the​ ​mandibles​ ​are​ ​a​ ​pair​ ​of​ ​forcipules​ ​(poison​ ​claws)
● At​ ​the​ ​terminal​ ​end​ ​of​ ​each​ ​forcipule​ ​is​ ​a​ ​fang
○ nutrition/digestion
■ Predators,​ ​many​ ​eat​ ​small​ ​arthropods
■ Prey​ ​is​ ​detected​ ​with​ ​the​ ​antennae
■ Prey​ ​is​ ​killed​ ​or​ ​stunned​ ​with​ ​the​ ​forcipules
● The​ ​neurotoxic​ ​venom​ ​is​ ​often​ ​painful​ ​but​ ​not​ ​always​ ​deadly​ ​to
humans
○ reproduction/development
■ Females​ ​have​ ​one​ ​ovary,​ ​and​ ​males​ ​have​ ​one​ ​or​ ​more​ ​testis
■ Females​ ​and​ ​males​ ​have​ ​a​ ​gonopod​ ​which​ ​aids​ ​in​ ​handling​ ​of​ ​the
spermatophore
■ Sperm​ ​transfer​ ​is​ ​indirect​ ​(via​ ​a​ ​spermatophore)
■ Some​ ​centipedes​ ​brood​ ​their​ ​eggs​ ​in​ ​clusters​ ​of​ ​15+
■ The​ ​female​ ​winds​ ​her​ ​body​ ​around​ ​the​ ​eggs​ ​or​ ​carries​ ​the​ ​eggs
between​ ​her​ ​gonopods​ ​for​ ​a​ ​short​ ​time​ ​before​ ​depositing​ ​them
○ Locomotion
■ Centipedes​ ​that​ ​are​ ​adapted​ ​to​ ​run​ ​have​ ​longer​ ​legs
■ Centipedes​ ​that​ ​have​ ​adapted​ ​for​ ​burrowing​ ​through​ ​soil​ ​and​ ​humus
have​ ​short​ ​legs​ ​that​ ​anchor​ ​the​ ​body
■ Eg
...
​ ​by​ ​tapping,​ ​drumming,
releasing​ ​pheromones
■ The​ ​eggs​ ​are​ ​fertilised​ ​from​ ​stored​ ​sperm​ ​and​ ​laid​ ​(up​ ​to​ ​300​ ​eggs​ ​at​ ​a
time)
● Some​ ​deposit​ ​eggs​ ​in​ ​soil​ ​or​ ​humus,​ ​others​ ​construct​ ​a​ ​“nest”
○ Locomotion
■ Most​ ​move​ ​slowly
■ Adapted​ ​for​ ​pushing​ ​through​ ​humus​ ​and​ ​leaves
■ The​ ​backward,​ ​pushing​ ​stroke​ ​is​ ​activated​ ​in​ ​waves​ ​along​ ​the​ ​length
of​ ​the​ ​body
■ pushing/burrowing​ ​is​ ​facilitated​ ​by​ ​the​ ​body​ ​plan
○ Defence
■ Compensate​ ​for​ ​slow​ ​gait​ ​with​ ​a​ ​calcareous​ ​exoskeleton
■ Some​ ​can​ ​roll​ ​up​ ​into​ ​a​ ​ball
■ Use​ ​repugnatorial​ ​glands​ ​to​ ​repel​ ​small​ ​animals
■ Bioluminescence​ ​may​ ​result​ ​in​ ​some​ ​millipedes​ ​being​ ​attacked​ ​less
Symphyla
○ Small​ ​class​ ​(about​ ​160​ ​species)
○ Live​ ​in​ ​soil​ ​and​ ​leaf​ ​mould,​ ​in​ ​most​ ​parts​ ​of​ ​the​ ​world
○ Very​ ​small,​ ​only​ ​about​ ​2-10mm​ ​long
○ Body​ ​plan
■ Trunk​ ​has​ ​12​ ​leg-bearing​ ​segments
■ The​ ​last​ ​segment​ ​carries​ ​a​ ​pair​ ​of​ ​spinnerets​ ​or​ ​cerci​ ​(usually​ ​act​ ​as
sensory​ ​organs)​ ​and​ ​long​ ​sensory​ ​hairs
■ Mouthparts​ ​are​ ​similar​ ​to​ ​insects
○ reproduction/development
■ Genital​ ​opening​ ​is​ ​on​ ​the​ ​ventral​ ​side​ ​of​ ​the​ ​4th​ ​segment
■ Male​ ​deposits​ ​150-450​ ​spermatophores​ ​on​ ​stalks,​ ​and​ ​the​ ​female
finds​ ​and​ ​eats​ ​them
○ Locomotion
■ Very​ ​fast,​ ​can​ ​twist​ ​and​ ​loop​ ​their​ ​bodies​ ​as​ ​they​ ​move​ ​through​ ​the
humus
● Probably​ ​an​ ​adaptation​ ​to​ ​avoid​ ​predators
Pauropoda
○ Fairly​ ​abundant​ ​class​ ​(about​ ​380​ ​species)
○ Widespread​ ​in​ ​temperate​ ​and​ ​tropical​ ​regions
Joanna​ ​Griffith​ ​(2017)

○
○
○

○

Minute,​ ​about​ ​0
...
​ ​in​ ​the​ ​southern​ ​ocean,​ ​dust​ ​blowing​ ​in​ ​from​ ​islands​ ​feeds​ ​plankton
blooms,​ ​increasing​ ​crustacean​ ​populations,​ ​increasing​ ​prey​ ​for​ ​many​ ​marine
mammals​ ​and​ ​birds
● Body​ ​plan
○ Two​ ​pairs​ ​of​ ​antennae​ ​(defining​ ​feature),​ ​mandibles,​ ​two​ ​pairs​ ​of​ ​maxillae
○ Highly​ ​specialised​ ​appendages
○ Walking​ ​legs​ ​on​ ​thorax​ ​and​ ​abdomen
○ Trunk​ ​anatomy
■ Composed​ ​of​ ​distinct​ ​and​ ​similar​ ​segments,​ ​and​ ​a​ ​telson
● Basic​ ​design​ ​is​ ​often​ ​modified​ ​by​ ​the​ ​fusion​ ​of​ ​segments
■ In​ ​some​ ​groups,​ ​the​ ​trunk​ ​is​ ​divided​ ​into​ ​the​ ​thorax​ ​and​ ​abdomen​ ​with
various​ ​numbers​ ​of​ ​segments
■ The​ ​thorax​ ​or​ ​anterior​ ​trunk​ ​segments​ ​are​ ​covered​ ​by​ ​a​ ​dorsal
carapace
● Often,​ ​the​ ​lateral​ ​margins​ ​of​ ​the​ ​carapace​ ​overhang​ ​the​ ​sides
of​ ​the​ ​body
○ Appendages
■ Biramous​ ​(divide​ ​to​ ​form​ ​two​ ​branches)
● There​ ​is​ ​a​ ​basal​ ​protopodite​ ​composed​ ​of​ ​a​ ​coxa​ ​and​ ​basis
○ Cuticle
■ Calcified​ ​(in​ ​contrast​ ​to​ ​most​ ​arthropods)
■ Epicuticle​ ​and​ ​procuticle​ ​contain​ ​deposits​ ​of​ ​calcium​ ​salts
■ The​ ​outer​ ​layer​ ​of​ ​the​ ​procuticle​ ​is​ ​pigmented​ ​and​ ​contains​ ​tanned
proteins
● nutrition/digestion
○ Large​ ​range​ ​of​ ​diets​ ​and​ ​feeding​ ​mechanisms
■ Eg
...
​ ​woodlice)
■ Have​ ​gills,​ ​which​ ​must​ ​remain​ ​moist
Hexapoda
● Includes​ ​animals​ ​that:
○ Shed​ ​an​ ​external​ ​cuticle​ ​when​ ​they​ ​moult​ ​(ecdysis)
○ Have​ ​an​ ​exoskeleton
○ Have​ ​a​ ​three-part​ ​segmented​ ​body
○ Have​ ​six​ ​(hex)​ ​jointed,​ ​paired​ ​appendages
● Body​ ​plan
○ Amalgamation​ ​of​ ​segments​ ​into​ ​functional​ ​units​ ​(tagmosis)
■ Three​ ​main​ ​regions​ ​called​ ​tagmata
○ Huge​ ​diversity​ ​of​ ​morphology​ ​from​ ​the​ ​same​ ​basic​ ​body​ ​structure
● Insecta
○ Largest​ ​group​ ​(about​ ​750,000​ ​species)
○ Very​ ​successful
■ Occupy​ ​most​ ​environments
■ Very​ ​ecologically​ ​important
○ Body​ ​plan
■ One​ ​pair​ ​of​ ​antennae,​ ​one​ ​pair​ ​of​ ​mandibles,​ ​two​ ​pairs​ ​of​ ​maxillae,
three​ ​pairs​ ​of​ ​legs
■ Three​ ​body​ ​sections​ ​(tagmata)
● Thorax​ ​is​ ​split​ ​into​ ​pro-,​ ​mesa-,​ ​as​ ​well​ ​as​ ​notum/tergum,
sternum,​ ​and​ ​pleurons
Joanna​ ​Griffith​ ​(2017)

○

○

○

○

● Abdomen​ ​is​ ​made​ ​up​ ​of​ ​9-11​ ​segments
■ Usually,​ ​there​ ​are​ ​two​ ​pairs​ ​of​ ​wings​ ​on​ ​the​ ​thorax
■ One​ ​pair​ ​of​ ​compound​ ​eyes
nutrition/digestion
■ Adapted​ ​to​ ​many​ ​diets
■ Modifications​ ​of​ ​mouthparts​ ​reflect​ ​how​ ​food​ ​is​ ​ingested
● Mandibles​ ​function​ ​in​ ​cutting​ ​and​ ​tearing
● Maxillae​ ​and​ ​labium​ ​function​ ​in​ ​food​ ​handling
● Piercing​ ​mouthparts
● Sucking​ ​mouthparts​ ​(eg
...
​ ​horseflies)
● Sponging​ ​mouthparts​ ​(eg
...
​ ​Cellembola​ ​(springtails),​ ​Zygentoma/Thysanura​ ​(silverfish)
Joanna​ ​Griffith​ ​(2017)

exite/endite​ ​hypothesis
● Wings​ ​evolved​ ​from​ ​a​ ​gill​ ​branch​ ​and​ ​a​ ​leg​ ​segment
● Eg
...
​ ​dragonflies)
● The​ ​evolution​ ​of​ ​sclerites​ ​has​ ​enabled​ ​insects​ ​to​ ​fold​ ​the​ ​wings
over​ ​the​ ​abdomen
■ Insect​ ​flight​ ​muscles​ ​are​ ​very​ ​powerful
● Huge​ ​mitochondria​ ​within​ ​the​ ​muscle​ ​cells
● At​ ​low​ ​body​ ​temperature,​ ​metabolic​ ​rate​ ​is​ ​low,​ ​so​ ​many​ ​flying
insects​ ​have​ ​to​ ​‘warm​ ​up’​ ​to​ ​enable​ ​flight
Coevolution​ ​of​ ​plants​ ​and​ ​insects
■ Two​ ​interacting​ ​partners​ ​change​ ​in​ ​relation​ ​to​ ​each​ ​other
■ Eg
...
​ ​strong​ ​selection​ ​placed​ ​on​ ​the​ ​ability​ ​to​ ​produce​ ​cyanide
for​ ​defence
■ Implies​ ​reciprocal​ ​linked​ ​interactions,​ ​which​ ​are​ ​difficult​ ​to​ ​prove
■ The​ ​evolution​ ​of​ ​flowering​ ​plants​ ​created​ ​a​ ​huge​ ​diversity​ ​of​ ​new
niches​ ​for​ ​insects
● About​ ​50%​ ​of​ ​insects​ ​are​ ​herbivores,​ ​but​ ​only​ ​9/30​ ​orders​ ​are
primarily​ ​plant-eaters
Order​ ​Coleoptera
■ Beetles
■ “Sheath​ ​wing”
■ Contains​ ​more​ ​species​ ​than​ ​any​ ​other​ ​insect​ ​order
● 40%​ ​of​ ​all​ ​insects​ ​are​ ​coleoptera
● 25%​ ​of​ ​all​ ​species​ ​are​ ​coleoptera
● 400,000​ ​named​ ​species,​ ​but​ ​estimates​ ​go​ ​up​ ​to​ ​8​ ​million
■ Older​ ​than​ ​the​ ​dinosaurs​ ​(the​ ​first​ ​“true”​ ​coleoptera​ ​appeared​ ​230mya,
in​ ​the​ ​Triassic​ ​period)
■ Body​ ​plan
● Coxae​ ​(first​ ​leg​ ​segments)​ ​are​ ​housed​ ​in​ ​a​ ​special​ ​cavity,
which​ ​makes​ ​beetle​ ​bodies​ ​very​ ​compact
○ Makes​ ​hind​ ​coxae​ ​immovable
● Elytra
○ Modified​ ​forewing
○ Protects​ ​the​ ​wings​ ​and​ ​body​ ​from​ ​damage​ ​and​ ​infection
(eg
...
6mph
Eg
...
​ ​mealworms​ ​are​ ​capable​ ​of​ ​degrading​ ​polystyrene
into​ ​usable​ ​organic​ ​matter​ ​at​ ​a​ ​rate​ ​of​ ​about​ ​35-40mg
per​ ​day
■ reproduction/development
● Some​ ​species​ ​(eg
...
​ ​leaf​ ​beetles​ ​(family​ ​Chrysomelidae)
○ Over​ ​37,000​ ​species​ ​in​ ​over​ ​2,500​ ​genera
● Beetles​ ​were​ ​among​ ​the​ ​first​ ​insects​ ​to​ ​visit​ ​flowers
○ Remain​ ​essential​ ​pollinators,​ ​especially​ ​for​ ​ancient
species​ ​such​ ​as​ ​magnolias​ ​and​ ​spice​ ​bush
Order​ ​Hymenoptera
■ “Married​ ​wing”
■ Known​ ​for​ ​extreme​ ​cooperation
● Build​ ​huge​ ​nests
■ Body​ ​plan
● Large​ ​diversity​ ​of​ ​sucking/chewing​ ​mouthparts
● Hind​ ​wings​ ​are​ ​connected​ ​to​ ​forewings​ ​by​ ​a​ ​series​ ​of​ ​hooks
● “Nipped​ ​waist”​ ​due​ ​to​ ​fusion​ ​of​ ​first​ ​abdominal​ ​segment​ ​to
thorax
■ Social​ ​complexity
● Hymenoptera​ ​contains​ ​the​ ​largest​ ​group​ ​of​ ​eusocial​ ​insects
○ Some​ ​are​ ​only​ ​primitively​ ​social,​ ​eg
...
​ ​queens,​ ​soldiers,​ ​workers
● Basic​ ​modifications​ ​to​ ​the​ ​body​ ​plan​ ​promote​ ​task
specialisation
○ Tending​ ​eggs​ ​and​ ​young
○ Providing​ ​for​ ​the​ ​colony​ ​(trophallaxis,​ ​the​ ​social​ ​sharing
of​ ​liquid​ ​food​ ​-​ ​also​ ​used​ ​to​ ​pass​ ​chemical​ ​signals
among​ ​each​ ​other​ ​and​ ​maintain​ ​a​ ​cohesive​ ​colony
identifying​ ​odour)
○ Defending​ ​the​ ​colony
■ Soldiers​ ​may​ ​have​ ​massively​ ​distorted
defensive​ ​structures,​ ​which​ ​may​ ​result​ ​in​ ​them
losing​ ​the​ ​ability​ ​to​ ​feed​ ​themselves
■ Eg
...
​ ​wax​ ​moth​ ​larvae​ ​(Galleria​ ​mellonella)
○ Eg
...
​ ​vampire​ ​moth​ ​(Calyptra​ ​minuticormis)
● Can​ ​be​ ​highly​ ​damaging​ ​pests
○ Four​ ​lepidoptera​ ​species​ ​are​ ​in​ ​the​ ​top​ ​ten
insecticide-resistant​ ​insect​ ​species
■ reproduction/development
● Holometabolous​ ​(complete​ ​metamorphosis)
● Mating​ ​and​ ​egg-laying​ ​occurs​ ​on​ ​a​ ​host​ ​plant
● Larvae​ ​are​ ​grub-like
■ Colouration
● Eyespots​ ​can​ ​deter​ ​vertebrate​ ​predators​ ​(proven​ ​to​ ​drastically
reduce​ ​mortality)
● Many​ ​species​ ​feed​ ​on​ ​toxic​ ​plants​ ​(eg
...
​ ​Heliconius​ ​melpomene​ ​and
Heliconius​ ​erato
■ Batesian​ ​mimicry:​ ​non-toxic​ ​species​ ​copying​ ​a
toxic​ ​species
● Only​ ​works​ ​if​ ​the​ ​toxic​ ​species​ ​is
common​ ​and​ ​the​ ​mimic​ ​species​ ​is​ ​rare
Order​ ​Diptera
■ flies
■ Highly​ ​variable​ ​ecology
■ Body​ ​plan
● Functional​ ​forewings
○ Rapid​ ​and​ ​agile​ ​flight​ ​in​ ​some​ ​species
○

○

Joanna​ ​Griffith​ ​(2017)

Variable​ ​mouthparts​ ​and​ ​body​ ​form
Halteres
○ Reduced​ ​hindwings
○ Beat​ ​in​ ​time​ ​with​ ​forewings
○ As​ ​the​ ​body​ ​turns​ ​in​ ​flight,​ ​gyroscopic​ ​forces​ ​are
exerted​ ​on​ ​the​ ​halteres
■ Sensitive​ ​hairs​ ​sense​ ​these​ ​forces
■ Allow​ ​the​ ​fly​ ​to​ ​make​ ​adjustments​ ​and​ ​stabilise
the​ ​body​ ​rapidly​ ​during​ ​flight
nutrition/digestion
● Some​ ​herbivorous​ ​species
● Many​ ​parasitic​ ​species
● Most​ ​feed​ ​on​ ​decaying​ ​organic​ ​matter
reproduction/development
● Holometabolous​ ​development​ ​(complete​ ​metamorphosis)
pests/disease​ ​vectors
● Order​ ​contains​ ​many​ ​of​ ​the​ ​most​ ​important​ ​disease​ ​vectors
○ Eg
...
​ ​Culex​ ​pipiens
■ Wings​ ​clear/membranous
■ Short​ ​palps
■ Body​ ​horizontal​ ​when​ ​feeding
■ Transmits​ ​encephalitis​ ​and​ ​filariasis
○ Eg
...
​ ​Cochliomyia​ ​hominivorax​ ​(the​ ​new-world​ ​screwworm)
○ Larvae​ ​feed​ ​in​ ​open​ ​wounds​ ​and​ ​living​ ​flesh
○ Infested​ ​wounds​ ​attract​ ​more​ ​oviposition
■ Thousands​ ​of​ ​eggs​ ​in​ ​one​ ​wound​ ​can​ ​kill​ ​cattle
within​ ​7-10​ ​days
○ Alternative​ ​hosts​ ​include​ ​humans​ ​and​ ​wild​ ​animals
○ Sterile​ ​insect​ ​technique​ ​(mass​ ​sterilisation​ ​and​ ​release
of​ ​male​ ​individuals)​ ​has​ ​been​ ​successful​ ​in​ ​reducing
the​ ​population
■ Barrier​ ​to​ ​reinvasion​ ​maintained​ ​by​ ​releasing​ ​50
million​ ​flies​ ​per​ ​week
● Flies​ ​can​ ​also​ ​be​ ​beneficial​ ​to​ ​humans
○ Eg
...
​ ​Tachinidae
■ Lay​ ​eggs​ ​on​ ​top​ ​of​ ​common​ ​pest​ ​insects,​ ​larvae
feed​ ​off​ ​the​ ​host​ ​and​ ​eventually​ ​kill​ ​them
● Biological​ ​control​ ​of​ ​winter​ ​moths​ ​in
North​ ​America
○ Pollinators
○ Waste​ ​disposal
■ Eg
...
​ ​Scathophaga​ ​stercoraria​ ​(yellow​ ​dung​ ​fly)
■ Eg
...
​ ​Strongyloides​ ​(threadworms)
Eg
...
​ ​Dictyocaulus​ ​viviparus​ ​(lungworms)
○ Vertebrate​ ​parasites
● Eg
...
​ ​Myrmeconema​ ​neotropicum
○ Induces​ ​fruit​ ​mimicry​ ​in​ ​the​ ​tropical​ ​ant​ ​Cephalotes​ ​atratus
Body​ ​plan
● Cylindrical​ ​bodies
● Body​ ​is​ ​covered​ ​by​ ​a​ ​tough​ ​cuticle,​ ​which​ ​they​ ​moult
● No​ ​circulatory​ ​system
○ Nutrients​ ​are​ ​transported​ ​via​ ​fluid​ ​in​ ​the​ ​pseudocoelom
● Body​ ​wall​ ​muscles​ ​are​ ​longitudinal
○ Contractions​ ​produce​ ​a​ ​thrashing​ ​motion
● Can​ ​infect​ ​humans​ ​and​ ​animals

Joanna​ ​Griffith​ ​(2017)



---