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BIODIVERSITY SEMESTER ONE NOTES
INTRODUCTION
Can refer to:
 Genetic diversity
 Taxonomic diversity (number of species, genera, families)
 A taxonomic unit could be a species, genus, family etc
Biological species concept (BSC)
 A species consists of populations of organisms
 They can reproduce with one another
 Reproductively isolated from other such populations
BSC problems
 Often impossible to find out whether two individuals can mate
 Some clearly distinct species can occasionally reproduce (captivity)
 Offspring may be sterile e
...
ligar, mule, tion
 Cannot apply to fossils
 Difficult to define species for prokaryotes (archaea and bacteria)
 Single celled organisms with very simple cells
 Different prokaryote ‘species’ regularly exchange DNA via horizontal gene transfer or lateral
gene transfer (antibiotic resistance)
 Bacterial species DNA similarity of 97% or more
Eukaryotic species
 Organisms with complex cells
 Multicellular organisms, plants, animals and fungi
 Between 5-9million species (estimates)
Variation in shape/scale
 Morphology
 Etruscan pygmy shrew ‘vs’ blue whale ~ 6x107 mass difference
 Ecoli bacterium ‘vs’ blue whale ~ 1
...
g
...
g
...
25 million
>400,000
Non radiometric  Magnetostratigraphy
>500,000
Geological Timescales
 Precambrian  4
...
5 billion years ago
 Formation of the earth  ~ 4
...
7 billion years ago (microbial mats)
 Palaeozoic Era  541 – 252 million years ago
 Cambrian explosion  520 – 540 million years ago
 The Cambrian explosion saw the relatively rapid appearance of the major animal phyla
 Chordata, Mollusca, Arthropoda

Mass extinctions
End – Permian extinction 252 million years ago
 Boundary between Palazoic and Mesozoic era
 96% of marine and 70% of terrestrial vertebrate species became extinct
 Cause was unclear, possibly due to volcanism in Siberia, leading to global warming
Mesozoic era 252 – 66 million years ago
 Dinosaurs, pterosaurs, mammals
KPg (KT) mass extinction event 66 million years ago
 Between cretaceous (end of Mesozoic era) and the Paleogene
 75% of species went extinct, non-avian dinosaurs, peterosaurs, animonites, plesiosaurs
 Massive comet/asteroid impact
 Widespread environmental devastation, firestorms, dust clouds blocking out sunlight, mega
tsunamis, at the same time there was a giant volcanic eruptions in India (Deccan traps) and major
changes in sea level
Cenozoic era 66 million years ago – present
 Radiation of modern mammals
 Origin of primates (purgatorus ~ 65million years ago)
 Radiation of modern birds

PROKARYOTES AND THE ORIGINS AND DIVERSITY OF EUKARYOTES
Structure of prokaryotes
 Structurally simple
 Metabolically complex
 Cell wall
 No nucleus
 Circular DNA
 No membrane bound organelles
 Simple cells, a single compartment containing cytoplasm bound by a cell membrane (Lipid Bilayer)
Cell wall
 Gives the prokaryotic cell its characteristic shape
 Three common shapes include
 Coccus/cocci  round or spherical (Streptococcus, Staphylococcus)
 Bacillus, rod shaped cells (Bactillus, Lactobactillus)
 Spiral/helical, spiral or helical shaped (Heliobacterpylari)
 Several other cell shapes
Size



Most prokaryotes cells are 1-10um
Most eukaryotes are 10 – 100um (10x larger)

Two broad classes of bacteria and gram staining
 Can be distinguished based on structure of the cell wall
 Gram staining, invented by Hans Christian 1884
 Gram positive bacteria have a thick layer (outer) of substance called peptidoglycan in their cell
walls
...

 Gram negative bacteria have much thinner peptidoglycan layer that is inside and outer
lipopolysaccharide membrane not stained by crystal violet, stained by a ‘counter stain’ which is
usually pink
How antibiotics work…
 Inhibiting peptidoglycan formation
 Penicillin works by preventing formation of the peptide crosslink
 The cell wall degrades and the ‘naked cell’ eventually bursts due to osmotic pressure

Antibiotic resistance
 The surface of bacteria may have projections known as pili
 There are several distinct types used for adhesion (sticking to surfaces) and for transferring
between bacteria
DNA and no nucleus
 Unlike eukaryotic cells, a prokaryotic cell has no nucleus
 The genome, usually a single, circular chromosome, lies in cytoplasm
 DNA replication, transcription and translation occur in the same compartment
 Additional small circular DNA molecules, plasmids, may also be present in the cytoplasm
 Most prokaryotes have singular circle chromosomes, with a genome size of ~0
...
Cell elongates and DNA is replicated
2
...
Cross wall forms completely around divided DNA
4
...
Mutation – change in DNA sequence
 2
...
MRSA)
 Also includes lactic acid bacteria

Archaea (Prokaryotes)
 Many but not all are extremophiles, they live in extreme environments
 Extreme Halophiles
 Salty water
 Such as ponds in San Fransisco Bay, calafornia
 Archaea looks red due to red pigments, making the water red
 Hyperthermophiles
 Love high heat
 Live in very hot water such as boiling water of hot springs in yellow stone national park
 Thermal vents due to high heat, high pressure
 Acidophiles
 Love acid
 Live in very acidic environments such as acid mine drainage
 Some can even survive in environments with negative pH values
 Many are also hyperthermophiles
Archaea are different from prokaryotes
 Peptoglycan absent from cell wall
 Chemical composition of cell membrane is different from bacteria
Eukaryotes
 Oldest definitive fossil evidence is 1
...
e
...
2 billion years ago
 around 500 million years agpo small plants, fungi and animals emerged on land
 since colonizing land plants have diversified into 290,000 species
Concept: land plants evolved from green algae
 green algae are the closest relatives of land plants
 photoautotrophs are capable of synthesizing their own food from organic substances using light as
an energy source
 green plants, algae and photosynthetic bacteria are photoautotrophs
Evolution of photoautotrophs
 likely evolved from chemoautotrophs (survive in hot springs)
 fossils of photosynthetic Archean bacteria
 photosynthetic species are found in both prokaryotes and eukaryotes
 eukaryote distribution includes algae and plants
 prokaryote distribution is throughout bacteria/archaea
Plastids are needed for photosynthesis
 they often contain pigments used in photosynthesis
 types of pigments change
 land plants and green algae share features
 chloroplasts containing chlorophyll
 starch as the photosynthetic storage product as they have cellulose in the cell walls
Chloroplasts
 found in cells of algae/plants/algal protists only
 the site of photosynthesis in eukaryotes
 contain their own DNA and 70S ribosomes
 decend from cyanobacteria that were eaten but not digester by a eukaryotic ancestor (that already
had its mitochondria)  Endosymbiosis
 chloroplast DNA is much more similar to the DNA in cyanobacteria than the DNA of the cells of
nucleus
Algae
 informal term for a large diverse group of photosynthetic organisms which are not necessarily
closely related
 polyphyletic, derived from more than one common evolutionary ancestor
 included organisms range from unicellular genera such as chorella, to multicellular forms such as
giant kelp (a large brown algae which may grow up to 50m in length)
 most are aquatic and autotrophic and lack many of the distinct cell and tissue types such as
stomata, Xylem, Phloem which are found in land plants
Chlorella
 unicellular
 contains the green photosynthetic pigments (chlorophyll – a) and ( - b) in its chloroplasts
 type of algae, the colour comes from the chlorophyll pigment
Phaeophyta (brown algae)
 photosynthetic
 pigment fucoxanthin
 gel-like cell walls (Algin) to cushion and prevent dehydration
 multicellular
 example includes kelp forest

Rhodophyta (red algae)
 multicellular
 red pigment (phycoerythrin)
 photosynthetic
 absorb blue/green light that penetrated deep water
 can be found down to 260m deep
 complex life cycles
 alternations of generations
Chlorophyta (green Algae)
 considered to be the closest ancestors of truw plants
 over 7000 species
 some colonial (volvox) with 1000 of flagellated cells
 some multicellular (ulva, sea lettuce)
 some live symbiotically with fungi to form lichens
 close relatives of land plants
What is a plant?
 Land plants form a monophyletic clade, Decend from a single common ancestor
Clade  a group of organisms believed to comprise all the evolutionary desendants of a common ancestor
LAND PLANTS
How are they different from algae?
 First vascular plants were successful on land because of the cuticle, positive layers for the
gametangia and the absence of herbivores
 Fossils from the saurian age (443
...
5 million years ago)
Rhyniophytes (Silurian)
 Earliest vascular plants, now extinct
 Had dichotomous branching but lacked leaves and roots
 Anchored by ribosomes (horizontal portions of stem) and rhizoids (water absorbing filaments)
Land plants History
 First appeared on land between 400/500 million years ago
 Adaptations were needed to survive in a dry environment
 Large plants also needed support and methods to disperse gametes, including ways to transport
water to all parts of the plant
Characteristics of land plants
 Cuticle
 Stomata
 Gametangia enclosing gametes
 Embryos in protective structure
 Pigments that protect against UV radiation
 Mutualistic relationships with fungus
 Spore walls containing sporopollerin
 Tough outer walls of plant spores/pollen grains
Soil




Ancient plants contributed to soil formation
Acids secreted by plants help break down rocks
Organic material from dead plants, dead organic matter (DOM) contribute to soil structure

Present day non-vascular plants
 Thought to be similar to the first land plants
 Grow in moist environments in dense mats
 Small with no system to conduct water from soil to plant parts
 Growth pattern allow water to move through mats by capillary action and minerals can be distributed
through the small plants by diffusion






Can grow marginal surfaces including tree trunks, rocks and even buildings
Mutualistic relationship with fungi, Glomeromycetes
Large mats of plant cover-like moss distribution
The earliest plants were colonized with fungi as they promote absorption of water/minerals

Alterations of generations
 All land plants have a life cycle with alternation of generations
 Cells in sporangia undergo meiosis to produce haploid, unicellular spores
 Spores develop into a multicellular haploid plant, the gametophyte, by mitosis
 Reduction of the gametophyte generation is a major theme in plant evolution
 In non-vascular plants the gametophyte is larger, longer-lived and more self-sufficient than
sporophyte
 In plants that appeared later this is reversed
 In non-vascular plants the gametophyte generation is photosynthetic
 the sporophyte may or may not be photosynthetic but is always nutritionally dependant on the
gametophyte and is permanently attached
Vascular system
 consists of tissue specialised for the transport of materials
 Xylem  conducts water and minerals from soil up to aerial parts of plant, some cells have lignin
which provides support
 Phloem  conducts products of photosynthesis through plants
Tracheid
 Are the main water-conducting element in Xylem
 Angiosperms have tracheid plus more efficient system of vessels and fibers
Evolution of tracheid
 2 important consequences
 Transport of water and minerals
 Rigid structural support (not needed in aquatic green algae)

Club mosses
 A minor part of today’s vegetation
 Club mosses, horse tails and ferns were a major element of carboniferous vegetation
Microphylls ‘vs’ Megaphylls
 The earliest plants lacked roots and leaves
 The club mosses and ferns show important new features
 True roots
 True leaves
 Two types of spores
 The first leaf type, Microphyll is small and has a single vascular strand
 The Megaphyll is a larger, more complex leaf, thought to have arisen from branching and
development of tissue between branches
Ferns







12,000 species
97% are in clade (Leptosporangiate ferns)
Sporangia walls only one cell thick
Borne on a stalk
Sporophytes have true roots, stems and leaves
Fern leaf starts development as a coiled ‘fiddlehead’

Fern lifecycle
 Spore mother cells in sporangia form haploid spores by meiosis
 Spores can be blown by wind and develop into gametophyte far from parent plant





Fern gametophytes produce Antheridia and Archegonia (sex organs) not always at the same time or
on the same gametophyte
Sperm swim through water to archeogonium to fertilize egg
Zygote develops into independent sporophyte

Secondary growth
 Late in the Devonian (geological time period), some plants developed secondary growth
 Thickened woody stems of Xylem
 419
...
2 million years ago
Evolutionary of seed plants
Terrestrial adaptations of seed plants
1
...
Gametophytes became reduced and retained within the reproductive tissue of the sporophyte
3
...
Zygote develops into an embryo packaged with a food supply within a protective seed coat
5
...
Gymnosperms  pines and cycads
2
...
Cycads  Cycadophyta 140 species
2
...
Gnetophytes  Gnetophyta 90 species, 3 Genera
4
...
The pollen grain then takes in moisture and begins to germinate, forming a pollen tube
that extends down toward the ovary through the style
...
The pollen tube proceeds to release the two sperm in the megagametophyte
...

 The haploid sperm and haploid egg combine to form a diploid zygote, while the other sperm and
the two haploid polar nuclei of the large central cell of the megagametophyte form a triploid nucleus
(triple fusion)
...
The ovary, surrounding the ovules, develops into
the fruit, which protects the seeds and may function to disperse them
...
Eventually the fly is smothered and drowns in
sticky fluid, covered in sticky exudes
...

 Venus fly trap has an even more sophisticated way of predation
...
6 tiny hairs are on each leaf so when a fly
strikes one hair, the fly can then carry on feeding however the plants timer has been set
...
10 days later the leaf reopens and a husk remains
...

Flowers
 80% of plant species on earth have flowers
 1 function is to enable the plant to produce offspring
 Features of flowers including colour, perfume, nectar and shape are used to attract
Sunflowers
 Turn to face the sun
 The warmth of the seeds causes the production of nectar and this lures in pollinators
 One after another, hundreds of florets produce pollen coated stamen
 Sunflowers have established a relationship with animals to secure pollination
The Role of bees
 As bees feed on the nectar they unwittingly brush against the pollen which they carry form flower to
flower, fertilizing the plant as they go
...

 Cradle Mountain in Tasmania is blasted by bitter Antarctic winds
...

 The plant appears to have an ingenious solution: the petals of the flower appear to be fused
together forming an insulated case around the stamens
...
During brief sunny spells the
plants warm up and start producing nectar
...
There is, with luck, time enough for pollination before the cold
winds kill the flowers
...

Another defence mechanism
 Some plants can even signal to each other about the presence of a herbivore
 They release a volatile, signalling molecules when eaten which warn other leaves near by
 These other leaves can be warned, they produce toxins
 The volatiles can also attract parasitotic wasps
Alarm pheromone
 When disturbed or attacked by predators, many Aphid species (Plant lice) release the alarm
pheromone E-ß-farnesence (Eßf) causing neighbouring aphids to disperse to avoid predation
 Eßf has a strong repellent effect when detected by aphids at a distance
 It has been shown to attack and arrest aphid natural enemies
 However its use in plant protection strategies has been hampered by its chemical instability
 Many plants produce Eßf naturally, but also produce a wide range of other sesquiterpenes
 A class of plant metabolite called terpenes and have molecular formula of C15H24

ORIGIN OF MULTICELLULAR ORGANISMS
Eukaryotes
 Complex cells
 Nucleus
 Organelles, membrane bound
 Complex cytoskeleton

...
g
...
g
...
7mm to 14m
Fossil Record
 Many molluscs have a hard calcareous (made of calcium carbonate) shell which fossilises well
 Soft tissues almost never preserved, so molluscs without a shell have very poor fossil records
 E
...
octopuses
 Oldest probable molluscs are snail like Helcionellids
 530-540 million years old (nearly Cambrian)
 Mollusc groups with good fossils can be used to correlate the ages of rocks in different locations
 Belemnites
 Ammonites
 Gastropods
Molluscs Body Characteristics
Calcareous Shell
 3 layers
 Outer periostracum
 Middle prismatic layer (columnar crystals of calcite)
 Inner Nacre (flat crystals)
Mantle
 Specialised organ adapted from the dorsal surface of body wall
 Secretes the shell in molluscs that have one
 Lost in several groups
Nervous system and Muscle
 The snail has a nervous system with a set of ganglia and nerve chords running through the
muscular foot
 The tentacles contain chemoreceptors and photoreceptors in the eye
The Radula
 A rasping ‘tongue’ with chitin ‘teeth’
 Characteristic mollusc feature
 Found in all molluscs except bivalves
 In addition to the radula, Cephalopods (squid, octopus, cuttlefish etc
...

 There is also a digestive system gland or Hepatopancreas
 Makes enzymes for extracellular digestion (pancreas like)
 Stores Glycogen
 Intracellular digestion
 Intestine
 Absorption of nutrients
 Anus opens into mantle cavity

Respiration and Circulatory System
 In aquatic molluscs, there is usually one or two feather-like gills (Cntenidia) housed in a cavity in the
mantle
 Land snails lack gills
 They have modified the mantle cavity into a primitive lung
 Most molluscs have a heart which connects to an open circulatory system
 Fluid not fully enclosed in vessels, bathes tissues directly
 Cephalopods have a closed circulatory system
 Allows higher activity
Blood
 Haemolymph
 Contains an oxygen transport pigment called haemocyanin which is blue when oxygenated
 Contains copper rather than iron as in haemoglobin
 Mollusc haemolymph also contains haemocytes
 Phagocytic cells
 Engulf and digest foreign material
 Important in immune defence
Excretion of Waste Products
 The heart of molluscs also acts as a filter
 Atria of the heart filter out waste products
 Nephridia (structures equivalent to kidneys) selectively reabsorb some molecules and release
further waste products
 Excreted as urine into mantle cavity
Reproduction
 Some molluscs are Dioecious
 Individual produces either eggs OR sperm
 Others are hermaphrodites, a single individual can produce sperm AND eggs
 Fertilization is internal in some molluscs and external in others
 Gonads release sperm and/or eggs (gametes) into coelom, Nephridia extract the gametes and
release them into the mantle cavity
 In many Cephalopods, males have a modified arm to transfer sperm to females
 The primitive larval stage of molluscs is a Trochophore
 Remember molluscs are part of Lophotrochozoa
 This matures and differentiates into the adult morphology
Major classes of Mollusca
 Polyplacophora  chitons
 Gastropoda  Snails etc
...

 Cephalopoda  octopus, squid, cuttlefish etc
...
g
...
g
...

 Shell in two halves (valves) hinged at dorsal line
 No radula and no distinct head
 Most are filter feeders, trapping particles in mucus covering the gills
 Powerful adductor muscles close shell
 Some can swim e
...
scallops
 In some, the foot may protrude for digging e
...
razor clams
 Giant clam (Tridacna gigas) largest living bivalve
 Can live >100 years
 Gets most of its nutrition from photosynthetic dinoflagellate endosymbionts (some group as
corals)
Class Cephalopoda
 Octopus, squid, nautilus, cuttlefish, many extinct groups
 E
...
belemnites, ammonites
 >800 living species
 Head surrounded by tentacels
 Mantle adapted to form siphon
 Move by jet propulsion
 Shell external, internal or absent
 Carnivorous
 Highly developed sensory and nervous system
 Cephalopods are sble to change colour using specialized cells called chromatophores
 Each containing a sac of pigment (Cytoelastic sacculvs)
 Contraction of the muscles around the chromophore alters the shape of the cytoelastic
sacculus, altering the colour
 Cephalopods have the most important/complex nervous system and exhibit the most complex
behaviour of any non-vertebrate
 Brain is housed in a cartilaginous ‘skull’

SKIN SHEDDERS
Introduction to Ecdysozoa
Protostomia/Protostomes to major groupings
 Lophotrochozoa (or Spiralia)
 Ecdysozoa
Name comes from:
 Ecdysis = moulting from the cuticle
 Zoa = animals

“Moulting animals”

Ecdysozoa characterised by:
 Moulted cuticle
 Cuticle  outer, non-cellular layer of the integument secreted by epidermis
 Moulting (ecdysis)  old cuticle shed and replaced by new, larger cuticle
 Allows the animal to grow
Ecdysozoa Phyla
Based on current evidence, 8 phyla are members of ecdysozoa
 5 worm-like phyla (Lack Paired appendages)
1
...
Loricifera
3
...
Nematoda
5
...
Tardigrada
2
...
Arthropoda
 Have paired ventrolateral (down and to the side) appendages = ‘limbs’
 These have completely independent evolutionary origin from limbs or vertebrates
Worm-like ecdysozoans
 Phylum Priapulida or Prapula
 Pirapulid worms or penis worms or cactus worms
 Marine, most species appear to be carnivorous
 True coelom probably present
 Straight gut with anterior mouth and posterior anus
 ~20 living species
 0
...
1 – 1mm in size
 Straight gut with mouth and anus
 Live in sediment
 Diet is uncertain, as are many other basic aspects of their biology
 ~30 species described, many more undescribed
Phylum Kinorhyncha – ‘worm like’
 Kinorhynchans or ‘mud dragons’ or ‘spiny-crown worms’
 0
...
1mm to >8m in length
 Occur in all ecosystems
 Including 3km under the earths surface
 Often the single most common group in an ecosystem
 80% of animals are nematodes
 25,000 species known
 1 million possible
 300 million years old
 Found everywhere
 50% of described species are parasitic (host survives) or parasitoid (kill the host)
 Some nematodes
 C
...
elegans are widely used in medicine
 Very simple multicellular organism
 Transparent
 Simple nervous system
 Easy to keep in a lab
 First multicellular organism to have entire genome sequenced, first draft in 1998
 20 thousand protein-coding genes (30,000 in humans)
Elephantitis (Lymphatic Filarisis)
 Caused by several different nematode species
 Spread by mosquito bites
 Worms infect lymph ducts
 Block the flow of lymph  oedema (swelling)
 Usually in legs and genitals
 Very long terms infection (years)
Phylum Nematomorpha ‘worm like’
 Horse hair worms or Gordian worms
 Superficially resemble nematodes but evolutionarily distinct
 Most 30 – 40cm long
 350 species described but probably ~2000+
 Parasitoid (kills host)
 Larvae parasitic on arthropods, adults free-living, usually fresh water
 Can modify behaviour of hosts to make them drown themselves
 Adult worm leaves body and lives in water
Phylum Tardigrada ‘arthropod like’
 Tardigrades or ‘water bears’
 ~0
...
5mm long
 4 pairs of legs
 Usually feed on plants or bacteria
 Often live on mosses and lichens
 Gut with mouth and anus
 Nearly indestructible, they can survive:
 Cooling to -272 and Heating to 150
 Pressures of 6000 atmospheres and 1000 times the radiation that kills humans
 Vacuum of space >10 days
 Dehydration for 10 years

Phylum Onycophora ‘arthropod like’
 Onychorans or ‘velvet worms’
 Segmented (although not very obvious)
 Multiple pairs of hollow, fluid filled legs tipped with claws
 Gut with anterior mouth and posterior anus
 Ambush predators (hunt using slime glands)
 ~180 described living species
 Tropics plus temperate regions of southern hemisphere
Onychophora and Arthropoda are closely related:
 Panarthropoda, in ecdysozoa
 Annelida is in a completely different group
 Lophotochozoa (or Spiralia)
 Phylum arthropoda
 >1 million described species
Hallucingenia
 Originally described in 1911 as a polychaete worm by Charles Doolittle Walcott, who did the first
study of the Burgess Shale fossils
 Restudied by Simon Conway Morris who in 1977 proposed radical new interpretation
 Member of unknown phylum
 ‘silt-walker’ with single row of tenticles on back
 Bulbous head
 In 1997 Ramsköld proposed
 No single ‘tentacles’ but pairs of legs
 Spines on back for defence

ARTHROPOD DIVERSITY
General features
 Segmented bodies
 Segments often modified
 Separate mouth and nus
 External hard covering
 With protiens, chitin (cuticular exoskeleton)
 Jointed appendages
 Paired legs, antennae, mouthparts
 Tracheal Respiration and/or gills in larger aquatic stages or book lungs
 Metamorphosis – may occur in advanced forms
 Ventral nerve cord (runs underneath body)
 Sensory organs and complex behaviour
Ecdysis (moulting)
 Shedding of the cuticle allows growth
 Neurosecretory cells produc hormone ecdysone
 Increase in epidermal cell activity, protein and RNA and glycogen reserves
 Premoult, moult, post-moult, intermoult
 Old cuticle separates from epidermis, partially digested, new cuticle laid down
 Body inflates, old cuticle shed
Individuals
 ~1
...
0x1023)
 Burgess shale
 Arthropod community (520 million years ago)
Cambrian ‘Explosion’
 535 – 510 million years ago
 Approx
...
are free from bacterial contamination use the blue blood from these
crabs

Arachnids
 Scorpions, spiders, harvestmen, mites, ticks
 All have eight legs
 Bodies consist of 2 parts
 Harvestmen have one fused section
 No antennae
 No wings
 100,000 species
Spider webs
 Silk-lined tube
 Cob web
 Sheet web
 Orb web
 No web (active hunters)
Class Arachnida: Order Acari (ticks and mites)
Diagnostic features
 ~30,000 species described
 Complete fusion of cephalothoras and abdomen
 Little sign of segmentation
 Head with mouth parts on a projection
 Adult has 4 pairs of legs, 1st larvae has 3 pairs
 Larva/nymphs  adult
 Eggs  larvae  nymphs  adult
 Free living, semi parasitic or fully parasitic
 May transmit (=vector) viral, bacteria or protozoan pathogens
Venomous spiders
 Latrodectus mactans (Black Widow)
 Loxoceles reclusa (Brown recluse)
 Atrax robustus (funnel web)
Mites
 Have a variety of lifestyles
Ticks
 Are ecto-parasites
Myriapoda
 Actually have 10 – 750 legs
 Have simple antennae and eyes
 Many extinct groups
Millipede (fossils up to 1m long)
Two pairs of legs per segment
Slow moving
Vegetarian
12,000 named species
Pauropoda
 Lack eyes and tracheal system
 Forked antennae
 5000 species

Centipede
One pair of legs per body segment
Fast moving
Carnivorous
3000 – 8000 names species

Symphyla
 200 species
 Small and translucent
Crustacea
 ~70,000 described species
 Lobsters, crabs, shrimps, barnacles, woodlice etc
...
1mm to 3
...

 Leaf litter
Protura (coneheads)
 800 species
 <2mm long
 Blind
 No Cerci (no tail)
 Densities 90,000m2
 Fluid feeders

INSECTS
Why are they important?
 Represent over 80% of the earths animal diversity
 Over 1 million species have been described
 Estimated number of 6 – 10 million species
 Insects are found in every terrestrial environment
 Many major pest species
 Some ‘social species’ – ants, bees have societies that rival those of humans in size and complexity
 They have been around longer than dinosaurs
 Insects are 479 million years old
 Fossilised insects of enormous size have been found from the Paleozoic Era when oxygen levels
were higher (35%) and allowed giant insects to exist
 Today oxygen levels are 21%
 Flight evolved 406 million years ago
 All major insect groups has evolved 345 million years ago
Big 3 insect orders:
 Lepidoptera
 Hymenoptera
 Coleoptera



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