FINAL

• important ecological role • support ecosystem function • interesting adaption

Arthropoda + Onychophora (velvet worms) + Tardigrada (waterbears) synapomorphy: segments body + walking appendages (legs) DNA sequence data legs independently evolved at least twice in animals -> evolved in panarthropoda before vertebrates came onto land

• restricted to tropics and subtropics, none outside of tropics • few species • in rotting wood • uncommon • gland on each side pair = opening of glands • produce liquid protein = slime • glands on mouth • predators

• animals (metazoans) with an exoskeleton • 1.1 million • most known and predicted unknown species are arthropods • shrimp, crab, lobster

• food source/support animals • pollination • decomposition • make ecosystem function, support us • primary pollinators in all flowers • essential roles in food webs and support large animals

• phylum Arthropoda synapomorphies: • presence of exoskeleton • molecular sequence data characteristics: - segmented body; segments grouped/functional units paired, joint appendages; mouthparts - metamorphosis: egg, immature (ex. larva), adult

• external skeleton: entire outer surface of animal; some internal parts • internal structures of exoskeleton: INVAGINATIONS • formed of chitin (polysaccharide) and proteins (sclerotin) = strong and flexible • continuous, but segmented = hard rigid plates (sclerites) connected by softer, flexible material (joints) • shed and renewed as animal grows • where muscles attach • entire outer surface and internal structures are part of exoskeleton • movement via hydrostatic pressure = expand + contract • folds

• change in form during post embryonic development; growth 1st: new exoskeleton forms underneath existing exoskeleton - soft, folded, flexible 2nd: molting: a process of shedding the old outer exoskeleton 3rd: growth after molting = hardening of exoskeleton can be no, or little change in form from one molt to next (ex. millipedes), or drastic change in form, as in most insects arthropods can’t grow without shedding old exoskeleton and growing new one hormonally regulated process of growth and development (pesticides can prevent molting = messing up hormones = death)

EXTINCT • only extinct major taxon of arthropoda: end permian mass extinction • one of most successful of early animals ~300 MY in oceans = marine and costal

• head; multi-segmented body • one pair antenna and 10+ pairs of legs • antennae: sensory appendages of head; detection of odours and touch • most millipedes: scavengers; basic chewing mouthparts (mandibles - ancestral condition) • centipedes, predaceous; mouthparts modified into fangs with venom • > convergent evolution to subdue the prey • > secondarily used in defence if necessary • curl into ball for protection • glands secrete toxins

synapomorphy: 2 body regions AND 2 pairs of antennae characteristics: • 5+ pairs of walking legs; additional legs often modified for swimming • mostly marine; f/w, few terrestrial

~50 000 described • essential in marine food webs ie. krill • human consumption: 10 million tons/yr • barnacles • few terrestrial • largest arthropod

synapomorphy: specialized mouthparts called chelicerae AND antennae absent chelicerae: primarily used in feeding, grab things: used in defence only when necessary, inject venom in 2 taxa: horseshoe crab and arachnida

• blue blood: hemocyanin, cooper turns blue • shallow ocean waters • 4 extant species • in decline from habitat loss • used in medicine, blood extracted

synapomorphies • 4 pairs of legs • 2 body regions (cephalothorax and abdomen) connected by pedicel (fused in some derived taxa) • legs and head attached to cephalothorax, never at abdomen

~100 000 described • fusion of abdominal segments • pedipalps: “palps”: second pair of appendages in mouth region to aid in feeding • palps can be larger than legs • thousands unknown • 12 orders (spiders are just one) • most predatory -> predatory and prey • most harmless • fear spiders dues to bad press, pop culture, negativity • consume liquid food • partial digestion outside body in all but complete digestion outside body in some taxa • scorpions, spiders, harvestmen

• mostly predaceous (but not all) because of their size, food source for many • the need to defend themselves, do not seek out others • 96% of terrestrial bird species in NA feed their young insects or other animals that feed on insects • most bird species are dependent on arthropods at some point in lifecycle • therefore need to defend themselves

• many arachnids have NO venom • ALL: partial digestion of prey occurs outside body -> specialized enzymes to inject into prey • SOME: complete digestion of prey outside body • if venom: allows arachnid to subdue a large prey individual, immobilize prey • differences btwn venoms and digestion secretions not resolved -> not really separate • spider venoms originate from digestive system • advantage: small arachnids are able to consume relatively larger or stronger prey

~1500 described ~24 w/ venom that can kill human - pedipalps huge, w/ strong grasping claws - abdomen: segmentation apparent, not fused - venomous tip: can be used in medical drugs - they grab things then venomous tip bends around to inject prey - parental care, cooperation -> mother carry on back - first animals to colonize land from marine ancestors in ocean and become fully terrestrial = survived the colonization of vertebrates

• arthropods and arachnids are prey for larger animals - fox severed the sail so it can’t sting it

• venom glands in palps • spin silk form glands that open on the chelicerae • tiny arachnids • independent origin of gigantic palps for grasping

• wind scorpions, wind spiders, sun spider • harmless to humans • aggressive due to defence, fast movements • chelicerae very large and obvious • palps larger than front legs • nocturnal

~6000 • harvestmen, daddy-longlegs • 2 body regions fused into round body • antenniform legs: 2nd • > modified in form and function to act like antennae • > for touch, sensory, odours • > chemoreceptors, send info to brain • NON-VENOMOUS: harmless • very long legs, there are short-legged ones • some predatory, scavengers, feed on small insects and fungi/plant • move their parts through mouth to clean • have trouble walking, their legs are made for climbing vegetation not for flat surfaces • not aggressive • large palps that look like legs - not a lot of muscle

• only in opilionids - male parental care in harvestmen = male protecting eggs