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Announcements

Lab Quiz todayOne minute per station

Postpone submission of first insectcollection until April 2

Propose Pepperwood trip in firstweekend of May

Circulation- dorsal heart– In pericardial

sinus– Muscular vessel

enclosed by bodywall anddiaphragm

– Valves preventbackflow

– Pumps pushblood fromposterior towardshead

Circulation- ventral diaphragm

– encloses

perineural sinus– contracts and

directs bloods

blood laterally

and backwards

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Ingestion, storage, grinding• Subdivisions

– Pharynx– Esophagous– Crop for food storage– Proventriculus- grinding organ (gizzard)

• opening to salivary glands

Digestive System• Salivary glands• gut• Malpighian tubules

– free ends distributed through hemocoel– Eliminates non-gaseous wastes– contents emptied into gut and eliminated through anus

Midgut• digestive enzymes secreted for absorption• peritrophic membrane

– non-living area separates food from epithelium sieves foodbetween inner and outer gut

– food circulates for digestion or conservation of digestiveenzymes

• subdivisions– ventriculus– gastric caecae

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Hindgut• Malpighian tubules absorb water, salts, waste amino acids and urea

from hemolymph• Transport urine to hind gut• Hindgut recovers water and nutrients• Uric acid and undigested food excreted

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Nervous system• Nerve cells aggregated into ganglia along

ventral nerve cord.• Coordinates motor, sensory, physiological

processes• Integrated with endocrine glands that

secrete chemical messengers (hormones)

Nervous systemTrends toward fusion and concentration of ganglia

beetle cockroach wasp fly bug

Neural organs in head• Brain- eyes, antennae, signals from body• Subesophageal ganglion- controls and

processes information from mouthparts

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Endocrine system

• Neurosecretory cells producemost insect hormones

• Hormones produced in neuronal,neuroglandular, or glandularcenters.

• Prothoracic glands (moltinghormones) and corpora cardiacaand corpora allata (juvenilehormone)

Interactions of endocrine and nervous systems

Muscles• Insects have only striated muscles• Crossbanding appearance from actin and

myosin

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Crawling locomotion• Walking with three

legs on ground atonce

• Larvae have circularand longitudinalmuscles pressingagainst hydrostaticskeleton

Flight(http://www.zoo.cam.ac.uk/zoostaff/ellington/aerodynamics.html)

• Muscles in thorax control wingbeats in adult insects• Each wingbeat consists of

– Downward forward motion– Upward and backward motion

• Vortices create extra lift

IndirectAttached tothoraxContract tomove wingup

DirectAttached towingStrong flight,weak hover

Flight musculature

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Detail musculature w indirect flight

• muscles deformthorax wherewings are attached

• thorax 'clicks'back into placewhen muscles arerelaxed

• found in moreadvanced insects

Reproductive system• Dioecious- female and male• Usually reproduce sexually, and both sexes present• If asexual reproduction, males absent• Internal fertillization• Sperm stored in spermatophore• Usually eggs laid, some live birth