exam 3 Challenges and Opportunities of Hard Structures Part 2

what processes occur through thin body surfaces

• gas exchange

• ions moving

• waste excretion

impermeable body covering

reduction of water loss

• critical adaptation for terrestrial habitats

solving gas exchange problem - Molluscs

• ctenidia = ciliated gills

  • in ancestral its in the posterior mantle cavity

  • feathery structure = increases surface area

• cilia = gas echange

Torsion

180 counter clockwise rotation of the visceral mass, mantle, shell relative to the head and food during the larval stage

• moves gills to the front

solving gas exchange problem - arthropods

• tracheal tubes

  • ridges prevent it from collapsing

  • thick and thin regions keep it flexible

  • delivers gases to and from each cell

  • circulatory system is reduced

metabolic waste

NH3

shell or exoskeleton prevents

loss of metabolic wastes by diffusion across general body surface

circulatory systems

takes the wastes that cells create

solving excretion problem in arthropods

• malpighin tubles or glands

• lie in hemocoel

circulatory systems need to distrubute

• gases

• metabolic wastes

to and from specialized surfaces/organs