BIOD43H3 Lecture Notes - Lecture 11: Peristalsis, Snake Scale
BIOD43 Lecture 11 Notes: Key Points
Recap-
Anterior fibers do POSITIVE (+) work in each cycle.
Posterior fibers do NEGATIVE (-) work at first, resisting lengthening. However, posterior fibers
end up doing positive work to fibers located towards the middle.
• WHITE FIBERS get recruited for faster swimming, and are more positive, even towards
posterior locations.
• Robust connective tissue is attached towards posterior locations.
Terrestrial Locomotion in Snakes
On land snakes push off of matter on the ground, such as stones, twigs, and uneven ground.
1)Rectilinear (Pythons, Boas)
• During rectilinear locomotion sections of snake body crawls along ground.
• Ribs walk forward. Traveling in a peristaltic wave motion
2) Concertina
• Movement when moving through tunnels and climbing
• During concertina locomotion, snakes anchor portions of bottom and side of body against
vertical walls
• Fairly slow movement
• Concertina movement takes more energy than slithering, for a given speed. Snakes are
not able to sustain concertina locomotion as long.
• Extra traction of snake scales when climbing
3) Lateral Undulation (slithering)
• Move undulatory wave backwards through body
• Similar to movement when swimming
4)Side Winding
• Sidewinder snakes move with a distinctive sideways motion.
• This side movement puts pressure on the ground, holding sand in place so the snakes
don’t slip as they travel.
• Sidewinders raise up most of their body to move in this fashion, because it reduces their
contact with hot sand.
• Compared to water, air is much less dense. For birds to remain in the air and fly, the
LIFT vector must be strong enough to overcome the force of gravity.
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Document Summary
Anterior fibers do positive (+) work in each cycle. Posterior fibers do negative (-) work at first, resisting lengthening. However, posterior fibers end up doing positive work to fibers located towards the middle: white fibers get recruited for faster swimming, and are more positive, even towards posterior locations, robust connective tissue is attached towards posterior locations. On land snakes push off of matter on the ground, such as stones, twigs, and uneven ground. 1)rectilinear (pythons, boas: during rectilinear locomotion sections of snake body crawls along ground, ribs walk forward. Snakes are not able to sustain concertina locomotion as long: extra traction of snake scales when climbing, lateral undulation (slithering, move undulatory wave backwards through body, similar to movement when swimming. For birds to remain in the air and fly, the. Lift vector must be strong enough to overcome the force of gravity. The aspect ratio of a wing is the ratio of its span to its mean chord.
