Biológia | Ízeltlábúak » Phylum Arthropoda

Source: http://www.doksinet Phylum Arthropoda Phylum Arthropoda Most “successful” lineage on Earth greatest biomass (>750 kg per person) numbers of species numbers of individuals number of ecological niches Phylum Arthropoda Subphylum Trilobitomorpha Class Trilobita Subphylum Chelicerata Class Merostomata Class Pycnogonida Class Arachnida Subphylum Mandibulata Class Crustacea Class Myriapoda Class Hexapoda From: Briggs & Fortey (2005) Wonderful strife: Systematics, stem groups, and the phylogenetic signal of the Cambrian radiation. Paleobiology supplement to Vol 31(2): 94-112 ARTHROPODA Why so successful? 1. Exoskeleton -allowed invasion of land & flight 2. Metamerism & limbs -allowed incredible limb modifications 3. Short life span & high fecundity -allows higher rates of evolution 1 Source: http://www.doksinet Subphylum Chelicerata Subphylum Chelicerata Apomorphies • No antennae (lost) • Chelicerae • Two tagmata – Prosoma & Opisthosoma

(no distinct head) Subphylum Chelicerata Chelicerae first two appendages modified for feeding, clawed - not mandibles Subphylum Chelicerata Chelicerae chelate (pinching) or venomous fangs or piercing stylets (for sucking body or plant juices) Sun scorpion Subphylum Chelicerata Pedipalps - 2nd pair of appendages modified for sensory perception communication catching prey conveying sperm (spiders) 2 Source: http://www.doksinet Subphylum Chelicerata Pedipalps Subphylum Chelicerata 12 appendages 1 pair of chelicerae 1 pair of pedipalps 4 pair of walking /swimming legs (3 pair in immature mites & Ricinulei) (1st pair sensory in many groups = 3 pair for walking) Most species are predators Most are liquid feeders (don’t chew) Gnathobases - grind prior to ingestion Subphylum Chelicerata Subphylum Chelicerata Three classes • Merostomata – relic, 4 species left • Pycnogonida – marine “sea spiders”, 1,000 spp. • Arachnida – spiders, scorpions, etc. 70,000 spp.

Subclass Xiphosura Class Merostomata Order Xiphosura - Horseshoe crabs Horseshoe crabs not crabs (not Crustaceans) closest extant relatives of eurypterids & trilobites • 4 species left (3 genera: NA, se Asia, Malaysia) “trilobite larva” – “living fossil” “evolutionary relic” • all marine, shallow (but oviposit on shoreline) • only chelicerates with compound eyes • primitive ! simple! 3 Source: http://www.doksinet Class Arachnida 4 Source: http://www.doksinet Class Arachnida • primarily terrestrial (marine origin) – few mites & spiders secondarily aquatic (some mites parasitize marine animals & some live in deep ocean trenches) • ~ 93,000 species Class Arachnida Among the earliest animals on land – Tracks 460-500 mya ? – Most activity from the Devonian (410360 mya) – Fossil mites, scorpions, spiders – 1 m long aquatic /amphibious scorpions • Most are spiders (37,000 spp) & mites (45,200 spp) Class Arachnida •

Respiration via 2-4 pairs of book lungs and / or rudimentary tracheae open via spiracles • Tracheae not homologous with those of other terrestrial arthropods (& not as efficient = lower metabolic rates) • Usually “sit & wait” predators Class Arachnida Class Arachnida Pumping stomach Species with tracheae rely less on blood for gas exchange (insects do not use blood for gas exchange) Book lung 5 Source: http://www.doksinet Spermatophore Class Arachnida ~93,000 species Orders 1. Aranae 2. Acari 3. (Solifugae) Solpugida 4. Uropygi 5. Amblypygi 6. Opiliones 7. Pseudoscopriones 8. Scorpiones 9. Schizomida 10. Rincinulei 11. Palpigradi Life in the undergrowth Data from: Coddington, J. A & Colwell, R K 2001 Arachnids, pp 199-219 in Encyclopedia of Biodiversity vol. 1 Academic Press No. described spp ~37,000 ~45,200 (~500,000 new?) 1,065 101 126 ~4,500 3,100 1,260 195 53 80 We will focus on those indicated in bold Class Arachnida Ricinulei Order Araneae - 7th

largest animal order • Spiders – Spinnerets, silk glands – Chelicerae modified into fangs - venom tubes – A few species dangerous to humans • Black widow, brown recluse, hobo(?) • Most spider “bites” are not – All predators, (on insects) SEM of Spider spinnerete & silk Gasteracantha sp. Silk proteins Spider silk used for: prey capture safety lines egg sacks aerial dispersal lines air bags for diving One of the strongest & toughest natural fibers known 5 times stronger than steel of same weight & more elastic than nylon Crab spider: Thomisidae 6 Source: http://www.doksinet Jumping spiders Salticidae . Orb-weavers Araneidae: Gasteracantha sp. Courtship dances by jumping spiders (Salticidae) by Dr. W Maddison (UBC) Class Arachnida Order Acari • Mites & ticks – Hyperdiverse – ~ 1 million undescribed species – rival nematodes & beetles in species # – Many parasitic – Herbivores & predators 7 Source: http://www.doksinet

Class Arachnida Order Acari • Prosoma & opisthosoma ~ fused • Ticks - vector pathogens, e.g • Lyme disease (Spirochaete bacteria) • Some plant pests • “Chiggers” & mange • Some aquatic spp. Class Arachnida Order Acari • Demodex folliculorum -the eyebrow mite -harmless, usually -cosmopolitan - < 0.4 mm Ixodidae: Amblyomma komodoense 8 Source: http://www.doksinet Class Arachnida Phalangium opilo L. Order Opiliones – “Daddy long-legs,” “Harvestmen” – No venom – 4,500 spp – Tagma fused – Trachea only – Have penis – Can eat solids Class Arachnida Order Pseudoscorpiones – ~ 3,100 species – Predaceous, in leaf litter & crevices – Often phoretic on flying insects – 7mm or less, usually 5 or less – Pedipalps large, pincerlike, no tail – Poison glands in pedipalps 9 Source: http://www.doksinet Class Arachnida Order Scorpiones – Terrestrial, largest bodied arachnid – Large, chelate pedipalps – 1,260 species –

Poison gland in tail – Aquatic 425 mya – Terrestrial 400 mya – Nocturnal Phylum Arthropoda Subphylum Mandibulata Good with curry! 10 Source: http://www.doksinet Phylum Arthropoda Subphylum Trilobitomorpha ! Class Trilobita ! Subphylum Chelicerata ! Class Merostomata ! Class Pycnogonida ! Class Arachnida ! Subphylum Mandibulata Class Myriapoda Class Crustacea Class Hexapoda Subphylum Mandibulata Subphylum Mandibulata Concept of Snodgrass 1930-1950s Three classes • Myriapoda – centipedes, millipedes, ~13,000 spp • Crustacea – shrimps, lobsters, etc. 45,000 spp • Hexapoda – insects, 1,000,000+ spp. Subphylum Mandibulata Crustacea + Myriapoda + Insecta Apomorphy • Mandibles (biting jaws) – Shared development & genetics Crustacea Hexapoda (Diplura) Hexapoda (Thysanura) Mandibles - developed from limbs 11 Source: http://www.doksinet Class Myriapoda Class Myriapoda Centipedes & Millipedes Largely homonomous body Class Myriapoda Centipedes -

Chilopoda • 2,800 species (8,000 total?) • Terrestrial (some marine?) Direct development (no larvae) <1 - 30 cm Class Myriapoda • Unwaxed cuticle & un-closable spiracles = moist habitats, nocturnal • Genital opening posterior Geophilomorpha Centipedes - Chilopoda Soil Centipedes • Predators Common • Poison fangs (1st limbs on trunk) Defensively produce HCN gas • One pair of legs per body segment No. body segments not constant even in a species 12 Source: http://www.doksinet Scolopendromorpha Scutigeromorpha Dorsal spiracles! Class Myriapoda Class Myriapoda Millipedes - Diplopoda Millipedes - Diplopoda • 7,000 species (80,000 total?) • No venom • Terrestrial • Trunk of diplosegments (2 segments fused) = 2 pair of legs per segment • Detritivores, herbivores • Genital opening anterior • Many with calcium hardened cuticle (tough! But also rare in acidic habitats) 13 Source: http://www.doksinet Hexapods Phylum Arthropoda

Subphylum Trilobitomorpha ! Class Trilobita ! Subphylum Chelicerata ! Class Merostomata ! Class Pycnogonida ! Class Arachnida ! Subphylum Mandibulata ! Class Crustacea ! Class Myriapoda ! Class Hexapoda Tagmosis & limb loss in the Insecta From hypothetical worm-like & myriapodlike ancestors CLASS HEXAPODA Characteristics • 6 walking legs (each of up to 6 segments) • 3 tagmata Note loss of limbs on abdomen Note incorporation of limbs as mouthparts CLASS HEXAPODA Fossil History No marine fossil hexapods? (Crustaceans?) Oldest fossil hexapods ~ 400 mya (Devonian) • Cuticle tanned with sclerotin (a lightweight protein) • Abdomen originally of 11 segments Reconstruction of Rhyniella praecursor Among the oldest terrestrial animals Devonian (400 mya) order Collembola - Rhynie chert of Scotland Rhyniella praecursor 14 Source: http://www.doksinet Family richness In fossil record Order Collembola - Springtails Fossil record Labandeira & Sepkoski 1993 Phylogeny

of the Hexapoda Collembola & Archeognatha Earliest Hexapods Fig. 81 Fig. 72 Phylogeny of basal Hexapoda Insecta Fig. 73 Dave Walter 15 Source: http://www.doksinet Subclass & Order Protura Ectognathy! • No antennae, wings, or eyes – (pseudoculus) see. p230-231 • Entognathous mouth – (mouthparts inside cavity) • 400-600 species, 8 families ~ 48 species in North America Dave Walter Subclass & Order Protura • Small (0.6-15 mm) see. p230-231 • Prolegs modified for sensory purposes • Tracheal system reduced • Anamorphosis - autapomorphic. Immature has few segments & more are added posteriorly during development Functionally a tetrapod Subclass & Order Protura • Inhabit soil, decaying vegetation, and rotting wood • Associated with fungus (thought to feed on mycorrhizal fungi) • Rare in collections, no? specialist in North America • Rarely seen alive - collected with Berlese funnels (as are Diplurans) Subclass & Order

Collembola • Abdomen reduced to 6 or fewer segments – Tracheal system reduced / absent • Entognathous mouth ( & no palps) – (mouthparts inside cavity) • 6,000-9,000 species, 700 in North America • Many undescribed spp. Dave Walter 16 Source: http://www.doksinet Subclass & Order Collembola • Abdominal seg 1 has collophore – Used for many purposes, incl. osmoregulation • Furca - “spring tail” a forked jumping organ • Small 2-3 mm, up to 12mm • With postantennal sensory organs (possible homologs of Crustacean 2nd antennae) • Molting continues for life (52 molts is the record) • Feed on decaying vegetation, fungi, etc. Subclass & Order Collembola • Ubiquity similar to Acari & nematodes – but not as many species • Ubiquitous & abundant (100,000+ / m 3 of surface soil & most common insect on Antarctica, -20m in fresh & marine habitats, Coenaletidae species live in shells with terrestrial hermit crabs!) • Found in

all habitats that contain metazoans – coldest to hottest (48°C volcanic vents) – treetops to deepest soils – some species can survive desiccation (anhydrobiosis, completely dry without death) – some species can survive without oxygen (more likely to survive nuclear war than cockroaches!) Symphypleona - globular Life in the undergrowth - Collembola First 4 abdominal segments fused Arthropleona - elongate Life in the undergrowth - Collembola - mating (Spermatophore placed on substrate) Which do you think is more derived? 17 Source: http://www.doksinet Archeognatha Alex Wild Palaeodictyoptera Dominant insects of the Paleozoic (50% of species) Beaked herbivores (83% of Permian leaf fossils showed evidence of herbivory) “Paleoptera” & Neoptera Fig. 72 End Permian extinction of superorder (multiple closely related paleopteran orders) Prothoracic paranotal lobes 18 Source: http://www.doksinet Order Odonata - Dragon & Damselflies • 5,500 species,

mostly tropical, predacious • Nymphs with extensible pre-hensile labial mask modified for grasping prey • Male copulatory organs on segments 2&3 but gonopore on segment 9 copulate in unique ‘wheel position’ • 360° vision - aerial hunters Phylogeny of the Hexapoda Order Odonata - Dragon & Damselflies • Two suborders hold 99% of species • Dragonflies: Anisoptera – Wings to side, larvae with rectal gills • Damselflies: Zygoptera – Wings vertical, larvae with 3 caudal lamellae (gills) Phylogeny of the Hexapoda Neoptera - 90% of Hexapoda Polyneoptera - Orthopteroids Paraneoptera - Hemipteroids Endopterygota (Holometabola) Fig. 72 Fig. 72 19 Source: http://www.doksinet 20 Source: http://www.doksinet Grasshoppers - Acrididae 21 Source: http://www.doksinet Katydids - Tettigoniidae - Tettigonia chinensis Phylogeny of the Hexapoda Phylogeny of the Hexapoda Neoptera Polyneoptera - Orthopteroids etc Paraneoptera - Hemipteroids Endopterygota

(Holometabola) Fig. 72 Fig. 72 Order Phthiraptera - lice • Dorsoventrally flattened • ~ 5,000 species (we have 2 species) • Eyes absent or reduced 22 Source: http://www.doksinet Phylogeny of human head/body louse Deep (old) split within the louse phylogeny 1.18 million years ago How is this possible if modern Homo sapiens is less than 0.2 million years old? H. neanderthalensis [06 mya] H. erectus [18 mya] Order Hemiptera Phylogeny of human head/body louse • Mapped onto phylogeny of genus Homo Bugs, hoppers, aphids, cicadas, scale insects, whiteflies, etc. • Largest non-endopterygote order (~90,000 spp) • Mandibles and maxillae modified as piercing stylets • Lack palps • In beak-like labium = rostrum or proboscis • Wings coupled in flight - fore & hind act as one wing H. neanderthalensis is too recent Deep split is consistent with split between H. erectus and our lineage one possible scenario Box 11.8 23 Source: http://www.doksinet Order

Hemiptera Fig. 75 “Homoptera” - Sternorrhyncha psyllids, whiteflies, aphids, scale insects “Homoptera” - “Auchenorrhyncha” Cicadas, spittlebugs, plant-, leaf-, & treehoppers - with tymbal acoustic system Cicadidae Cicadellidae Coccoidea - coccids, scales, mealy bugs Gerromorpha: Gerridae Flatidae Cercopidae Nepomorpha: Corixidae 24 Source: http://www.doksinet Cimicidae Cimex lectularius Swallow bugs Cimicomorpha Assassin bugs Plant bugs Lace bugs Minute Pirate bugs Bed bugs Fig. 72 Carabidae Staphylinoidea Scarabaeoidea Cucujiformia Cerambycidae Chrysomelidae Curculionidae 25 Source: http://www.doksinet Fig. 72 26 Source: http://www.doksinet Order Siphonaptera - fleas • 2,500 species, apterous, laterally compressed • Ectoparasites of birds & mammals ~ 74% use rodents as hosts • No compound eyes, (ocelli or none) • Piercing & sucking mouthparts • DNA & new morphological data suggest fleas evolved from within the Mecoptera

(sister to snow fleas - Boreidae) Order Trichoptera - caddisflies • Aquatic larvae with hook-bearing prolegs at end of abdomen • Larvae make cases, or are free-living • Sister order to the Lepidoptera - Very well supported 27 Source: http://www.doksinet Order Trichoptera - caddisflies • Wings with hairs, rarely scales • ~11,000 species with moth-like adults • Diverse feeding habits - predators, detritivores, adults often do not feed Aquatic Hexapods - 30,000 species (370 marine) Major contributors • Odonata • Ephemeroptera • Plecoptera • Hemiptera • Megaloptera • Coleoptera • Diptera • Trichoptera Minor contributors • Collembola • Neuroptera • Hymenoptera • Orthoptera • Lepidoptera • Blattodea Order Lepidoptera - moths Order Lepidoptera - moths • “Microlepidoptera” - 40% of species • Antennae typically filiform or plumose (moths) or knobbed / clubed (butterflies) – small – Lots of leaf miners • Macrolepidoptera - 60% of

species – Larger bodied – With tympanal organs in some lineages (Many are tuned to detect bat sonar) • Butterflies are modified, diurnal moths • “moths” paraphyletic with respect to butterflies • ~160,000 species (14,500 butterfly species) Butterflies - 82 Alaskan species, Ken Philip 28 Source: http://www.doksinet Silk moths - Saturniidae 1,500 species Order Hymenoptera - ants, wasps, bees • Flight driven by forewings - hindwings coupled to forewings with small hooks (hamuli) • ~100,000 species (36,000 in NA - more than Coleoptera; may outnumber global Coleoptera due to many tiny parasitoid wasps; estimated that 60-96% of the order is undescribed) • Many species beneficial to humans - pollinators & parasitoids (biocontrol) • Haplodiploidy - females diploid, males haploid Order Hymenoptera - ants, wasps, bees Traditionally, two suborders: – “Symphyta” (wood wasps & sawflies) • 3 segmented thorax • Larvae caterpillar-like &

phytophagous – Apocrita (ants, bees & wasps) • Propodeum (abdominal segment 1) joined to thorax = mesosoma remainder of abdomen is the gaster (or metasoma) • One clade with ovipositor modified into sting Order Hymenoptera - ants, wasps, bees Four basic life patterns: 1. the primarily phytophagous “Symphyta” 2. the parasitic or gall-making Apocrita 3. the non-social Apocrita whose larvae are fed prey or pollen captured by the mother 4. the social Apocrita 29 Source: http://www.doksinet Prolegs continuous to posterior Lepidoptera larvae not so - have a ‘gap’ 30 Source: http://www.doksinet 31