2 - Terrestrial locomotion Flashcards
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The need for locomotion
Life progressed from uni-cellular to multi-cellular – there was a need to (a) support and (b) move to overcome gravity and/or water pressure/currents/wind
- defense
- escape
-search for food
reproduce
- avoid overcrowding
Locomotion def
The coordinated movement btwn support structures, joints, muscles and other tissues
Endoskeleton derived from
Derived from MESODERM
Exoskeleton derived from
ECTODERM
Muscle pair names
- Flexors & extensors
- Adductors & abductors (which open and close a clam shell)
Advantages of endoskeleton
- allow to grow large
- better defense
- more precise and controlled movement
Fundamental properties of Hydrostatic skeletons
- liquid incompressibility
- ability to assume any shape/ fill a container
Hydrostatic skeleton def
- Enclosure of a fluid-filled chamber (COELOM) with sets of opposing muscles
- a system in which muscles contract in one part of the body and force fluid to another region of the coelom where muscles are relaxed
- changes the shape of the body or extends it in one direction
- Sphincter muscles around openings to control the loss/intake of fluid
What controls the loss and intake of fluid?
Sphincter muscles
Pseudopodia def
False leg - forms in any direction to lead the organism in that way (amoeboid mvmnt)
Cilia def
Tiny hair-like structures which act as oars and beat to propel the organism forward - requires immersion (ciliary mvment)
Flagella def
Whip like appendages protruding from body.
Oscillates to propel forward - requires immersion (flagellar mvmnt)
Locomotion organs
- Cilia
- Flagella
- Pseudopodia
- Hydrostatic propulsion
- Limb mvmnt
Immersion def
(in water)
Hydrostatic propulsion def
Uses a series of muscles and fluid filled chamber with CONTROLLED opening/closing to propel body forward.
Limb mvmnt def
Uses a series of muscles and either an exoskeleton OR hydrostatic skeleton
Limb types
- legs
- tube feet
- wings
Locomotion modes
- Change locomotion throughout lifetime
- More than one form of locomotion
- Same structure for multiple functions (crustacean uses rhythmic mvmnt of thoracis appendages for walking and gas exchange)
- Same function can be done by different structures (jumping - legs or special structures such as furcula in springtails which flicks)
- Convergent evolution = diverse taxonomic groups may use same locomotion (Undulatory - nematode worms and marine worms, despite their distant)
Terrestrial locomotion
- Crawling
- Walking, running, jumping
Aquatic locomotion
- Rowing
- Undulatory mvmnts
- Specialized fins
- Jet propulsion
Aerial locomotion
- Flight
- Gliding
- Ballooning
Crawling
- soft bodied
- fluid filled cavities
- two-anchor method - body extended anteriorly by contraction of CIRCULOR muscles on fluid cavity (hydrostat) (CATERPILLARS)
- one anchor method - extends foot thru substrate, dilates the end of foot to anchor the tip of foot & then draws the body thru substrate using CONTRACTILR muscles of foot (Bivalve)
- Peristatic mvmnt - muscle contraction and relation creates a versatile mvmnt system based on principles (annelids)
Principles of peristaltic movements
- incompressibility of liquids
- ability to fill or take any shape
Types of peristalsis
Retrograde - changes in elongation and shortening occur in opposite direction to mvmnt (Segmented)
Direct - changes in segment volume during elongation and shortening occur in direction of mvmnt (Unsegmented)
Walking, jumping and running def
- Having legs or parapodia (or un-joined protrusions)
- involves coordinate mvmnt of uniramous appendages in different planes
Burrowing invertebrates
- short legs
- slow and powerful gait
Gait def
Manner of mvmnt or pattern of mvmnt of limbs
Longer limbs =
Reduce force, but increase speed (Fast running insects)
Subphylum Myriapoda
1 - Millipedes (Diplopoda) - 2 legs per segment, slow but powerful GAIT
2. Centipedes (Chilopoda) - one longer leg per segment, fast but not as powerful
Uniramous def
Single series of segments
Leg interference
Can slow down organism, make it prey
How is leg interference avoided?
By the placement of the tips of ADJACENT legs at different distances from the body
How do fast running insects move?
Have legs of slightly different lengths and move in an alternating tripod sequence
How do insects walk on water?
By balancing the pull of gravity on their extremely light weight with the physical properties of water (buoyancy and surface tension)
- These insects have waxes over exoskeleton to repel water, and microscopic hairs that trap air bubbles, allowing them to float.
- Water surface bends under each leg and the depression pushes the animal upwards (Water striders, Coleopterans and springtails)
- Have high SA:V ratio
Jumping in springtails
Associated with furcula (forked appendage at end of springtail)
How do the sensory and mechanical feedback systems play a role in locomotion?
The CNS generates motor commands that activate the musculoskeletal system of the insect, which then acts on the external environment
Sensory feedback = guidance and equilibrium and rapid feedback from mechano-sensors
Viscoelastic preflexes act to resist perturbations (muscles = motors, brakes or springs).
