Not primarily reliant on visual or chemotaxis Figure: study showing groping vs pounce (webover) hunting being dependent on the environment
Chase and wells: chemicals being glutamic acid, AMP, and glycine Lee: chemicals being proline, ATP, and crab extract Problems with studies: Chase and Wells -> no specific direction set, used chemicals (not natural); Lee -> lab-reared animals that were selected for preferencing crab, used chemicals (not natural) My question: how would octopuses respond to a more natural trial of chemotaxis?
- By using live crabs
Explain tank and experimental set-up Essentially a Y-maze (no mixing between arms), 2 set-ups: blind and visual – blind trials = black plexi dividers so octopus couldn’t see the crab with opaque holed boxes for crabs with water flow through them, visual = clear plexi dividers with plexi boxes for crabs
Used 2 octos: to try and reduce personality induced behavior Allowed for acclimation time, then removed grating and gave the octopus 40 min to make a choice A choice was made when the octopus’ head passed around the T structure into one arm of the maze Type of trial and the arm containing the prey were randomized to reduce learned behavior
Behavior: color changes/responses to visual clues
Mention briefly a little bit about the crab species: Green shore crab, local species, grows up to 5 cm, lives in tide pools, common SDS-PAGE for protein analysis, PCR for gene expression
Salad spinner: 2.5 min Water bath for 1 hour Collect and freeze water samples After hour, immediately kill and remove gills Fixate one gill from each in Tri-Reagent for RNA isolation Fixate one gill from each in CelLytic to fixate protein
Hemocyanin: used to carry oxygen (of course there’d be a TON in the gills) Arginine kinase: helps maintain ATP levels by the phosphorylation of "phosphagens" which serves as a high energy source from which ATP can be replaced quickly, and can bind actin Superoxide dismustase: destroys radical oxidative species (in mitochondria), which can be excessively generated during times of stress Brachyurin: serine protease that degrades collagen Cuticle protein: from exoskeleton (contamination)
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