Arthropoda special charactersArthropoda special characters

ExoskeletonExoskeleton Defining characteristics of arthropodsDefining characteristics of arthropods Compatible with mobility and growthCompatible with mobility and growth Protein and polysacharide (chitin)Protein and polysacharide (chitin) Functions:Functions:

• Protect surface from abrasion & attacks by Protect surface from abrasion & attacks by pathogenspathogens

• Structural support, maintain body shapeStructural support, maintain body shape Hardening accomplished by sclerotization Hardening accomplished by sclerotization

(chemical reaction called tanning – hardens, (chemical reaction called tanning – hardens, strengthens and darkens cuticle by cross-links strengthens and darkens cuticle by cross-links between protein molecules) or mineralization between protein molecules) or mineralization (incorporation of calcium salts)(incorporation of calcium salts)

Molting – to enable growthMolting – to enable growth

EcdysisEcdysis

Life Life cyclecycle

Stages of crustacean moult cycleStages of crustacean moult cycle Intermoult (Stage C)Intermoult (Stage C)

• Free of moulting activitiesFree of moulting activities• Normal day-to-day activities e.g. feedingNormal day-to-day activities e.g. feeding

Proecdysis (Stage D1-D4)Proecdysis (Stage D1-D4)• Preparation for moulting – ends with new cuticle Preparation for moulting – ends with new cuticle

detached from new cuticle but still covers the bodydetached from new cuticle but still covers the body• Feeding stops, nutrients from reserveFeeding stops, nutrients from reserve• Moulting fluid released (mixture of chitinases and Moulting fluid released (mixture of chitinases and

proteinases – hydrolyse old cuticle)proteinases – hydrolyse old cuticle)• Blood calcium increased – reclaimed from old cuticleBlood calcium increased – reclaimed from old cuticle• New epicuticle protect epidermis from hydrolyzed New epicuticle protect epidermis from hydrolyzed • Old and new epicuticle and exocuticleOld and new epicuticle and exocuticle

Stages of crustacean moult cycleStages of crustacean moult cycle Ecdysis (Stage E)Ecdysis (Stage E)

• Actual shedding of the old exoskeleton, hideActual shedding of the old exoskeleton, hide• Shedding starts at the ecdysial linesShedding starts at the ecdysial lines• Intake of air or water causes animal to swell – stretch to Intake of air or water causes animal to swell – stretch to

the new size and split the old exoskeleton along ecdysial the new size and split the old exoskeleton along ecdysial lineslines

• Normally eats the exuviaeNormally eats the exuviae Post ecdysis (post moult Stages A and B)Post ecdysis (post moult Stages A and B)

• Soft, cannot support itselfSoft, cannot support itself• New endocuticle secretedNew endocuticle secreted• Hardening takes place – calcified by transfering Ca from Hardening takes place – calcified by transfering Ca from

blood. Protein sclerotized.blood. Protein sclerotized.• Excess water (or air) removed from soft tissues, detach Excess water (or air) removed from soft tissues, detach

from the exoskeleton.from the exoskeleton.

Ecdysis: ProcessEcdysis: Process

Ecdysone (Y-organ), moulting fluidEcdysone (Y-organ), moulting fluid Number of moulting depends on Number of moulting depends on

speciesspecies Final moulting = terminal moltingFinal moulting = terminal molting Decapod – molt-inhibiting Decapod – molt-inhibiting

hormone by X-organ in eye stalkhormone by X-organ in eye stalk* Crab mating* Crab mating

Terminal moultTerminal moult

COMMUNICATION

- very important esp. for social invertebrates e.g. bees…. - chemical – e.g pheromone

-Functions: - identify sexes- tract line e.g. ants- biological pest control

- advantage: - effective in dark, - can pass around obstacles- can disperse over great distances- may last several hours

- disadvantage: - low speed of transmission- less information

COMMUNICATION

- visual - e.g. flash light, dance

- auditory - e.g. sounds –

1) movements / of wings,

2) movements of hind legs against wings

e.g. cricket – different sound according to species

3) vibration of chitinous abdominal membrane - cicada

- very important and unique for social insects ‘ colony (termites, ants, bees, wasp etc.)

Honey bees- swarming – colony divides to several divisions- 20,000 – 80,000 workers per colony- queen + some workers “swarm” to new colony

Ratu baru tetas

Penerbangan nuptial

Kopulasi dgn jantan (dron) – dron pecahkan organ pembiakan dlm ratu - mati

Dgn sperma + sebhg pekerja, swarm mbtk koloni baru

Bertelur 1000 sehari

Kelenjar mandibular ratu hasilkan feromon

kepada pekerja

Pekerja bekalkan nutrien kepada telur

Tetas jadi pekerja

Kerja2 penyelenggaraan / maintenance- rembes lilin bina srg, simpan mknn, jaga larva

Keluar dr srg cari makanan

Rehat & kawal sekitar srg

Kurang feromon dihasilkan

Pekerja bina sel2 royal

Telur diletak atas sel2 royal + royal jelly

Tersenyawa, tetas jadi ratu baru

Tak tersenyawa, tetas jadi dron

Jarak sumber mknn < 8 m – isyarat kimia

Jarak > 8 m – isyarat visual – tail wagging dance – maklumat ttg jenis mknn, lokasi, jrk sumber (frekuensi wagging tinggi – dekat)

3 minggu

> tua

Tail wagging danceTail wagging dance

-Reference – the sun

-Direction of food refers to the angle of dance direction compared to the location of the sun

-Location of food translated to frequency of tail wagging

Reference – the sun!Reference – the sun!

Other danceOther dance