Advanced Invertebrates

Circulation

Support, Growth & Movement

Nervous Systems (cont’d)

Circulation

• mollusks– bivalves and gastropods – open w/ hemolymph &

heart– cephalopods – closed w/ heart

• annelids – closed w/ aortic arches• arthropods

– crustaceans – open– chelicerates – open– uniramians – open w/ heart & aorta

• echinoderms – cellular diffusion

Support, Growth & Movement

• mollusks– Gastropods

• have 1 shell• exhibit torsion• move w/ wavelike contractions

of foot

– Bivalves• have 2 shells• move with “hatchet foot”

extruded from body

Support, Growth & Movement

• mollusks– Cephalopods

• jet propulsion

• stabilize with fins sometimes

• can crawl• very malleable body

Support, Growth & Movement

• annelida– longitudinal

muscles – circular muscles– parapodia –

stumpy leg-like appendages

– setae – bristle like hairs

Support, Growth & Movement

• arthropods– molt to grow larger – shed exoskeleton– unprotected until new exoskeleton hardens

– many muscles– jointed appendages allow full range of motion

Support, Growth & Movement

• echinodermata– metamorphosis from bilaterally symmetrical

larvae called bipinnaria to radially symmetrical adult

– movement with a water vascular system

Neural Control & Sensory Organs

• annelids– chain of ganglia– ventral nerve cord connects ganglia in each

segment

– setae

Neural Control & Sensory Organs

• arthropods– crustaceans

• paired ganglia• pair of branched antenna & pair of antennules, sensory hairs• compound eyes on stalks

– chelicerates• brain• simple eyes: usually three or more

– uniramians• brain & ventral nerve cord• paired ganglia in each segment• antenna & sensory hairs• simple & compound eyes• tympanum: sound sensing

Neural Control & Sensory Organs

• echinodermata – nerve ring– radial nerves