Locomotion - Terrestrial

Question 1

what is locomotion and why is there a need for it?

Answer 1

The co-ordinated movement between support structure, joints, muscles and other tissues.

Need to support, and over come gravity/water pressure, defense, foraging, reproducing.

Question 2

What are support structures?

Answer 2

Rigid skeletons Hydrostatic skeleton

Question 3

What is a rigid skeleton?

Answer 3

Can be edno or exo.
Endoskeleton is derived from mesoderm and exoskeleton derived from the endoderm.
Can either be articultaing or fixed.
Varies in complexity and materials.
muscles are usually attached to these support structures, flexors and extensors extend across joints and are used to move limbs.
Adductors and abductors used to open and close (clams).

Question 4

What are the advantages of an endoskeleton?

Answer 4

• Large size allowance
• Better defence
• More precise and controlled movement.

Question 5

What is a hydrostatic skeleton?

Answer 5

Fluid filled chamber with sets of opposing muscles.
A system where muscles (circular and longitudinal) contract in one part of the body and force fluid to another part of the coelom where muscles are relaxed.
changes the shape of the body, and extends it on one direction
Sphincter muscles around openings to control the loss/intake of fluid.

Question 6

What are locomotion organs?

Answer 6

1. Pseudopodia
2. Cilia
3. Flagella

Question 7

What are psuedopodia?

Answer 7

forms in any direction to lead the organism in that direction - “false leg”

Question 8

What is cillia?

Answer 8

Tiny hair like structures, act as oars and beat to propel the organism forward, generaly requires immersion.

Question 9

What is flagella?

Answer 9

Whip like appendages protruding from the body. Also ocillating to propel the organism forward

Question 10

What is hydrostatic propelsion?

Answer 10

Uses a series of muscles and fluid-filled chamber with controlled opening/closing to propel body forward.
Uses a hydrostatic skeleton.

Question 11

What is locomotion limbs?

Answer 11

Uses a series of muscles and either an exoskeleton or hydrostatic skeleton. Limbs include legs, tube feet, wings.

Question 12

What are locomotion models?

Answer 12

1. organisms can change thier locomotion as it progresses in its life cycle/ developmental stages. Butterfly [what is another example?- mosquito, flies.]
2. One species can have more than one form of locomotion.
   Crabs.
3. Some animals may use the same structure to simultaneously accomplish multiple functions. Crustaceans may use rhythmic movements of its thoracic appendages for both walking and gas exchange. [what are other examples? - Cephalopods, sea urchins]
4. The same locomotor function may be accomplished using different structures. jumping can be accomplished either by using legs, as in some insects or by using special structures.
5. As a result of convergent evolution, species in diverse taxonomic groups may use the same pattern of locomotion - undulatory swimming seen in polycheates and worms.

Question 13

Arieal locomotion models?

Answer 13

Flight
GLiding
Ballooning

Question 14

Terrestrial locomotion models?

Answer 14

Crawling
Walking, running, jumping

Question 15

Aquatic locomotion models?

Answer 15

Rowing
Undulatory movements
Specialised fins
Jet propulsions

Question 16

Crawling locomotion

Answer 16

Many soft bodies invertebrates.
Use fluid-filled cavities.

• Catepillars and leeches use a “two-anchor” technique. The body is extended anteriorly by contraction of circular muscles of the hyrdostat.
• Bivalve mollucs use “one-anchor” technique to burrow - extends the foot through the substrate, dilates the end of the foot to anchor the tip of the foot and then draws the body through the substrate using the contractile muscles of the foot.

Peristaltic movements - invloves a conbination of muscle contraction and relaxation creates a versatile movement system based on relatively simple physical principles - incompressibility of liquids and their ability to fill in or take any shape.

Question 17

What is retrograde peristalisis?

Answer 17

the changes in elongation and shortening occur in the direction opposite to the movement.

Question 18

What is direct peristalsis?

Answer 18

a change in segment volume during elongation or shortening, in the direction of movement.

Question 20

Walking, running and jumping locomotion

Answer 20

Walking and running associated with having legs (e.g. insects) or parapodia in some polychaetes.
In burrowing invertebrates, legs are usually short and the gait is slow and powerful. Longer limbs reduce the force but increase speed. Longer limbs and longer strides are typical of fast-running insects.
Walking involves the coordinated movement of uniramous (= a single series of segments) appendages in different planes.
Interference across legs when walking or running can be highly costly as it can slow down the organism and therefore, become an easy prey.
Leg interference is prevented by the placement of the tips of adjacent legs at different distances from the body
Fast-running insects have legs of slightly different lengths and move them in an alternating tripod sequence as shown below.
Some spiders and insects can 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 walk-on water insects have waxes over their exoskeletons to repel water molecules and microscopic hairs that trap very small air bubbles allowing the insect to float.
Jumping associated with legs in most invertebrates but furcula in springtails.

Both sensory and mechanical feedbacks play a role in controlling locomotion. The central nervous system generates motor commands that activate the musculoskeletal system of the insect, which then acts on the external environment. Sensory feedback includes guidance and equilibrium (from light blue) and rapid feedback from mechano-sensors (dark blue). Viscoelastic preflexes (red) act to resist perturbations (muscles = motors, brakes or springs).