Video 1

Gastropods and Torsion

Coils in the shell is different then torsion

-In gastropod shells, diverse shell forms, coiling is consistent

-Consequence of the whirling of the shell: the whirls are on a single plane snail tends to be heavier on one side then the other tends to be right side, they have to angle their body back to hold center of gravity to the center of their body. their shell is tilted

-Dextral and sinistral


  • Happens in the larvae stage
  • Left and right tinidia, gills, digestive tract, nerves, everything moves
  • Consequences: waste material moving over the mouth,
  • tested reason or torsion, larvae has higher predation having mantel cavity in front, sense what is coming and can avoid predation (theory)

-Several groups there is an absence or detorsion, either doesn’t do it at all or do it and then undo it


-Eyes on eye stalks, have different body structure, diverse

-Slugs are shell-less pulmonates, can have small internal shell

-Pneumostome- holes in their body , air goes internally into body. O2 CO2 exchang

Video 2


-2 shells that are connected at a hinge

-Scallops, clams, muscles


-Water comes in the incurrent siphon, and goes out through the Excurrent siphon- posterior end of clam

-Anterior end where the rings are

-Right hand and left hand shell

-Bivalves have extended siphons

Some have byssal threads that allow them to attach to rocks

– Water current through clam generated by action of cilia (beating of cilia)

-Gills are for gas exchange,  also modified to collect food particles from water, filter feeding, has ecological impact keeping the water clear

-10 cubic meters of water for every square meter of substrate

Gas exchange

-Counter current exchange

  • used for heat reg.
  • Used in excretion
  • water flows in one direction, blood through vessels in the gill is flowing in other direction
  • Concurrent flow- water is losing O2, blood is gaining, reaches equilibrium and stops, doesn’t really happen if it did it would be bad
  • If you run in opposite directions, maximizes the diffusional gradient, steeper the gradient the quicker the rate of diffusion, always a different O2 of water always going to be higher then the blood, doesn’t reach equilibrium

Video 3


-Exclusively marine

-They have similar structures (Mantals ect) but has different function

-Nautilus- spiral shell divided into chambers, active carnivores, tentacles modification of a foot,

-Septa divides the shell

-Liquid can be transported by the siphuncle

-Incredible good visions, form images

-Jet propulsion, allows for quick movement

-closed circulatory system, blood flows through arteries, veins, and capillaries, systemic heart, has bronchial hearts-allows blood to be circulated to tinidea

-Deep water organism- Architeuthis

Loligo Opalescens

-Skin of cephalopods contains layers of tiny cells called chromatophores, pigment containing cells

-Can biolumines if presence of photophores

-Cephalized, capacity for learning, memorize,

-Study shows capacity for octopus to learn, leaning by observing other octopus






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