Phylum Artropoda Flashcards
Phlyum Arthropoda
General feature:
- bilat symmetry
- bodies divided into ring/segments
- jointed appendaged - legs, antennae or mouthparts
- chitinous exoskeleton partitioned by chitinous plates
- haemocele body cavity w/ haemolymph bathing int organs
- Ecdysis - shed exoskeleton
Importance
Allergic reaction, envenomization , dermatitis, disease carrier
Classification
1. Class Insecta -
- head, thorax, abdomen
- 1 pair antenna, 3 pairs legs on thorac, w/w/o wings
2 - Class Arachnida
- cephalothorax (head, thorax fused) and abdomen
- 4 pairs of legs, wingless, no antennae,
- incomplete metamorphosis
- mauth can inc pair of poison jaws(chelicerae) paired glands (venom discharged)
3 - Class Crustacia
- cephalothorac, abdomen
- 4 pairs legs, 2 pair antenna, wingless, mainly aquatic
Scorpions
Morphology
- elongated terrestrial
- large pedipalps terminating in stout claws
- chelicerae
- non-segmented cephalothorax w/ 4 pairs of legs + elongated abdomen
- hooked stinger on posterior to discharge venom
- median eye
- vivparous (live young)carry young on back on females
Symptoms
Venom=toxaalbumin > paralysis, convulsions + pulmonary disorders
Treatment
Tourniquet, venom removed by suction
Pain relief w/ icepack
Spiders
Morphology
- cephalothorax
- chelicerae
- pedipalps (appendage lateral to chelicerae)
- abdomen w/ spinnerets
Spin webs to trap flies and other insects, paralyse with venom + suck body juices
Lifecycle
Development by gradual metamorphis
Eggs laid in masses usually encassed in a cocoon in which the young remains for long periods > larva in summer
rodents = primary reservoir > nymph in spring > incidental host > adult (pass through 8/9 molts before becoming mature adults)
*Lactrodectus mactans - black widow most dangerous in US
Symptoms
depend on location and amount of venom
Most frequent site is buttocks/genitals of male
Patient -> dizzy, weak, nausea, shock
Ticks
- Order Acarina
Morphology General
- Hairless/short haired leathery body
- Exposed armed hypostome (hard mouth part)
- Pair spiracle near coxae of fourth pair of legs
Family Ixididae (hard ticks),
- seed shape
- Horny scutum (hard dorsal sutum on anterior dorsal surface of F but covers all of male)
- Capitilum project from ant end (see from above)
Reddish cephalothorax & abdomen fused into body w/ 4 pairs segmented legs arising from plates of basal coxae
- Mouth inc: hypostome (median has transverse rows recurved filed like teeth anchors to host), chelicerae (dorsal paired chitinous - cutting orhansto allow hypostome insertion)+ 4 jointed pedipalps
- Eyes on/near ant lat margin of scutum
- cosmopolitan distribution
Soft ticks
- raisin shaped
- cosmo distrib but more in warmer climates
- capitulum not visible dorsally
- spiracles in front of 3rd pair of unspurred coxae
- tarsi have no pads/pulvilli
- coxal glands between 1st 2 coxae secrete tenacious fluid during feeding and copulation
Vectors of: Lyme disease, rocky mountain spotted fever, relapsing fever, tulareemia, tick-borne meningoencephalitis, colardo tick fever, Crimeans-Congo hemorrhagic fever, babesiosis
Ticks - Lifecycle + Disease
Life cycle (both blood suckers) - 4 life stage 1-2 years
1 - F lay 1000’s eggs in sheltered ares
2 - > larva (6 legged w/ anal pore) hatch w/i W>M depending on ext environment > remain on ground/low vegetation waiting for host (detect via Co2 sense organs) > attach
N.b. larva to adult also have 2 lat pores to anal por for breathing, amt portion legs contain olfactory organ, breathing siphon
3 - >nymph (8 legged w/ anal pore) after feeding on host for several days and molting > feed on appropriate host [hard ticks have 1 nymphal stage + soft have multiple]
4 - > molt > Adult > find 3rd host
N.B. use capillary blood pressure to feed. To attach to host , cut w/ celicerae, hypostome anchors during blood meal
To remove
- use fine tipped tweezers to grasp head and removing by pulling upwardly w/ steady even pressure.
- don’t remove from abdomen as can release bacteria and don’t leave head there as can cause infection
- fire/ petroleum may cause it to burrow deeper
- Clean bite area and hands w/ alcohol, iodine scrub / soap + water
Symptoms
- Lymes disease (from bacteria- characteristic bullseye rash
- itch, swelling, redding around bite
Ixodes dammini transmit
Borrelia burgdoferi > Lymes
Babesia microti > Babesiosis
Mites
Family Sarcopitidae (scabies)
Morphology
- smaller than ticks w/o leathery covering
- spiracles present of idiosoma of some mites and unarmed hypostome
- most have cosmo distrib
- Scabiei sm, oval, dorsally convex, ventrally flat, eyeless
- M smallr than F (200-250um v 330-340um)
- ant notothorax has 1st 2 pairs of legs
- mouth -> toothed chelicerae, 3 jointed conical pedipalp + labial palp fused to hypostome
-1st 2 pairs of legs term in long tubular processes each w/ bell shaped suckers + claws - post legs end in long bristles (4th pair M have suckers)
dorsal surface - spines, scales, bristles
Mites - Life cycle
Mites
Eggs deposited in spil/skin of host > 6 leg larvae > feed on blood/plant juices > metamorphose > 8 leg nymp > 8 leg adult
Scabies
Live in slightly serpingous cutaneous burrows
1 - night F burrow into skin activated by warmth 2-3mm/day.
2 - Male excavates lateral pockets/ branches in burrows
2 - F (during lifespan of 4-5W) deposits 40-50 eggs in burrow
3 - Larvae emerge usually in day 3
4 - Hexapod larva either form lat branches/ new tunnel > eightlegged nymph [F have 2 nymph stages, M have 1]
5 - Life cycle completed in 8-15 days & female can survive off host for 2-3 days at rooms temp]
6 - transmitted via personal contact
Pathogenecity -
Prefered sites = interdigital spaces, flexor surface, inguinal areas etc
- slightly reddish elevated tracts in skin
minute vesicular swelling
- intense itching
Diagnosis - type of lesion and itching rash = suggestive
Control - treat infected individuals, sterilize garments, bedding + personal cleanliness
Class insecta
General morphology
Head (6 fused segments) - appedages - sensory organs e.g. antennae, compound/ simple eyes, masticatory organs
Thorax - 3 segments (prothorax, mesothorax, metathorax) - winged insects can have wings on each meso and metothroax
Abdomen - 11 segments , no appendages, last segments can be modified for sexual purposes
Spircacles can be present for respiraton
Digestive system - pharynx, oesophagus, proventriculus, stomach/midgut, hindgut, rectum and anus (blood sucks have muscular pharynx) Paired salivary glans
Repro - M= 2 testes, seminal vesicle, accesory gland, hypopygium, F = ovaries, oviducts, seminal receptacle (spermatheca), shell, cement glands, oviposter
Important vectors of disease. Special interest = fleas, lice, bugs, flies
Lice - exclusively human
Favour hair on head, body, pubic areas
Vectors of typhus(crowded jails, famines, armies), relapsing fever, trench fever
Infect by blood meal of diseased person + Infect others via bites/wounds
Typhus - causative organism = Rickettsia prowazeki
Relapsing fever - Borellia recurrentis
Trench fever - R. Quintana (seen lots in WW1)
Fleas - blood sucking ectoparasites
Temporarily infest mammals and birds for feeding
May act as mechanical vectors via bacterial + viral diseases mainly via contaminated feces wind borne onto mucous membranes)
Plague - gram negative bacilus Yersina pestis (transmit rat-rat), Pulex irritans vector
Epidemic/marine typhus - Rickettsia typhi (excreted in flea feces) rat-rat-human
Dog tapeworm - P irritans = intermediate host
Reduviid bug - North + central America
Vectors of trypsonoma cruzi - multiply in mid + hind gut infective stage > transmit when defecates and contaminates bite/wound/mucus membrane
Anopheline mosquitos - Simian Malaria
Anopheline + culicine - vectors of avian malaria
Order Anoplura - sucking lice
Pediculus hominis (head)
Phthirus pubis (crab louse)
Pediculus humanus humanus (body louse)
Morphology
Morphology
Dorsoventrally flat
Flattened elongated gray-white body
Ovoid head - simple lateral eyes, short antennae, extensile piercing stylets
Fused chitinous thorax - 3 pairs of lehs terminating in sg hook like claw amd opposingtibial process for gripping hairs/fibres
Segmented abdomen - last seg of F has genital opening and 2 lat blunt gonopods which clasp hair during oviposition
Crab louse = smallest
Body louse more robost than head
Order Anoplura - Lifecycle + disease
Definite host - human
Worldwide distriution
Life cycles
Average: crab (15 day), body/head (18d), life span is 1 month
1) Nites- 0.6-0.8mm white eggs, can firmly attach to hairs/ clothing fibres (remain viable for 1m), hatch in 5-11 days at 21oc-36oC
Metamorphosis incomplete
2) Nymph develops within egg and emerges via opened operculum
3) 3 molts w/i 2 W > adult
4) Crab louse usually fixed on 1 spot and feed on blood periodically w/o moving and lay eggs close to base.
Hair louse move around head lay nits close to peripheral end of hair
Transmission
via close contact or nits in hair of clothing
Disease - epidemic typhus, trench fever, relapsing fever
Head + crab louse don’t transmit disease
Body louse transmit Rickettsia prowazekii, Borrelia recurrentis, R quintana
Diagnosis - itch, scratching, find adult lice/ nits
Treatment - topical application to soothe skin, remove by hands, topical preparations
Order Hemiptera Cimex lectularis (genus cimex)
Species inc C lectularis (common bedbug) and C. Hemipterus (tropical bedbugs)
Morphology
F slightly larger than M
Oval, dorsoventrally flat
Chestnut-brown bodies covered w/ short stout, simple/serrated hairs
Head - prominent compound eyes, slender antennae, specialized mouth parts in long proboscis flexed backwards
Thorax - each seg has pair of legs term w/ claws. Hind wings absent and forewings reduced to sm pads
Eggs - white ovoid, 1mm, oblique projecting collar like ring w/ operculum at ant end, coated w/ adhesive gelatinous substance
Habitat - feed at night preferably on human (also feed on other sm mammals), conceal selves in day in crevices of bedstead/matresss, easily transported
Lifecycle (lifespan= 6-12m)
1) deposit up to 200 eggs at rate 2/day white ovoid eggs
2) hatching at days 4-10, incomplete metamorphasis > larvae (yellow-white)
3) 5-6 molts at about 1 W intervals > adult
Pathogenicity
Bite > red, itch,
Minimal transmission of human disease (can act as mechanical carrier but not vector)
Order siphonaptera - Pulex Irritans (fleas)
Blood sucking ectoparasite
Morphology
small, brown wingless 2-2.5mm w/ compressed lat bodies
Small head - may have eyes and combs, all have antennae and suctorial mouth part
THorax - legs terminating in claws
Both sexes suck blood
Eggs - white/cream coloured 0.5mm
Larva - active wormlike white eyeless, legless, bristled creature, 14 segments, around 4-5mm
Host - domesticated wild animals (esp wild rodents), can leap host-host
Life cycle (life span about 1 year i nfavorable cool moist temp, in host max survival is 38-125 days)
1) adult feed on host while larvae live on nutritive debris (esp dried bloof and feces of adult)
2) F must copulate >1x and take freq blood meals. Fertilized F burrows into host skin and feeds and grows. Eggs deposited in sm batches under rugs in floor cracks/on ground
3) Fleas develop metamorphosis stage in host environment
4) 2-13 days larva emerge from egg, larval period last 7-30 days
5) molt 3x with last stage being pupal cocoon (pupal stage last 2-3W at low temp)
6) adult flea break out of cocoon
Disease
Plague - gram negative bacilus Yersina pestis (rat-rat) - human infection from direct contact w/ rats
Intermediate host of dog tapeworm (Echinococcus granlosus)
Mosquito - Genus Culex and genus Anopheles
Life cycle
Life cycle
1) eggs laid one at a time or attached to each other forming rafts in water > fertilized by spermatoza
2) Eggs hatch after 1-3 days at 30C or 7 days at 16C > elongated limbless larva [resting anopheline larvae suspend horizontally and culicine hang at angle to water]
(eggs mainly hatch w/i 2 days but some might withstand subzero winters b4 hatching)
Larvae feed of algae, bacteria etc
3) Molts 4x (4 instars) becoming longer each time > become >10cm
4) 4th instar larva > megalocephalic curved pupa (comma appearence)
5) pupal skin ruptured by air vesicle and activity of escaping adult insect. Rests on surface of water to dry and allow body to hrden. Blood feed + mating not occur for 2 days.
Genus Culex v Genus Anopheles mosquito
Eggs - 0.7mm encased in 3 layered shell w/ funnel shaped passage for entry of spermatozoa
- Culex - brown coloured, lay eggs in rafts of upto 200
- Anopheles - lay one at a time
Larvae - limbless, simple/transverelt brached tufted hair symmetrically arrangedo n body. Head (eyes, antennae, chewing mouth parts). Abdomen (8th seg have spiracles, anal aperture surrounded by papillary process i.e. anal gills for absorption)
Culex -lie at angle to water surface, siphon tube for breathing
Anopheles - no siphon tube, lie parallel to get oxygen
Pupa - develops from 4 instar, comma shaped.(resting, non-feeding stage)
Thorax (respiratory trumpets and air vesicle between future adult wings).
Abdomen - pair overlapping paddles w/ terminal hairs on last segments - allow it to dive rapidly in succession in jerky somersaults in response to stimuli
Adult
Head - spherical, elongated mouth part(adapted in F for sucking - proboscisgrooved labium, upper labrum epipharynx, hypopharynx, stylet pair manibles and serrated maxillae), long 15 jointed antennae, plumose in and pilose in F. Covered in compound eyes
N.B maxillary palps of F =long and slender, M = long ornamented like antennae w/ hair tufts (plumed appearence)
Thorax - rigid, covered by dorsal scutum. Prothorax (salivary glands). Wings
[only F suck blood]
Vectors -
Anopheles - human simian malaria
Culex - Arbovirus (fever, headache, malaise, hemorrhagic fever, encephalitis), filiariasis (nematode infection)
Culex + Anopheles - viral encephalitis
Phlebotomus papatasii
aka sandfly
Vector of leishmanias
Cosmopolitan in tropical and subtropical countries in the old world
Morophology
Slender and yellowish or buff coloured and are small. Bodies and wins are v hairy and lack scales
Antennae also hairy and have cutting organs
Life cycle - eggs > larva > pupa > adult
1) 30-36 hours after blood meal > F fly lay eggs in dark moist earea
2) 6-12 days after > eggs develop into segmented caterpillar like larvae w/ long caudal bristles
3) 4 molts in 25-35 days before it becomes buff coloured pupa w/ triangular head and curved abdomen
4) 6-14 days > adult fly emerge from pupa
