Chapter 31 - Animal Support and Locomotion

Notes for Chapter 31:
Support, Protection, and Movement

Click link to return to Lecture Schedule
or back to Chapter 6
or ahead to Chapter 7 (under construction)

Under Construction!

Check back for completed notes.

Please note: Contrary to notes previously posted
here, I will partly cover some concepts related to
support and locomotion on 9/5, in addition to
introducing Ch. 7. Sorry for the confusion.

For now, study the lecture notes below and
continue studying Ch. 7, or move ahead to Ch. 8.
We will cover a combination of Chs. 7 and 8 on 9/10.

Chapter 31 Assignment:

Ch. 31: 642-647, 650-653; RQ31: 1,5,9,11,12

Introduction: Of Grasshoppers and Superman
Featured Animal: Ants

For an excellent explanation of why ants could not even walk IF they were as large as humans, let alone lift more than their body weight (as they do routinely), see this Flying Turtle webpage

Notes for Lecture on Locomotion and Support:

Skeletons

- Metazoans all depend on a skeleton
- Particularly important for locomotion
- Also used for withstanding elements

Animals

dramatic size increase
single- to multicellular
directed movement

Evolution of mutual systems

locomotion and support
Four locomotory patterns
ameboid
ciliary/flagellar
hydrostatic
limb

Most animals live in water

move through water
or move water over body
Face problems of fluid dynamics
solid body with surrounding liquid

The size of an animal can dramatically affect its locomotion in water

source of image

The same is true for flying animals moving through air

Reynolds Number (Re)

dimensionless ratio: inertial forces/viscous forces
more precise formula:
((body size)(fluid speed))/(kinematic viscosity)

Engineers worrying about problems of waterflow tend to use
Reynolds Number as well.

Online calculators: 1 - 2 - 3

Excellent figures illustrating how turbulent flow (y axis is drag) changes from
Re = 0.1 to 1,000,000 (x axis)

Lots of fun illustrations here

See factors affecting how krill (euphausids) swim here

Useful for characterizing organism's life:

size: small <-> large
Re: low <-> high
fluid viscosity: high <-> low
inertia: low <-> high
currents: laminar <-> turbulent

Animals swimming through water behave differently:

Large "nekton" (inertial forces dominate)
Large whale (v = 10 m/sec)
Re = 300,000,000
Tuna (v = 10 m/sec)
Re = 30,000,000

- viscosity unimportant
- inertia carries animal forward
- flow of water becomes turbulent

Small "plankton" (viscosity dominates)

Copepod (v = 20 cm/sec)
Re = 300
Typical metazoan larva (v = 1 mm/sec)
Re = 0.3
Sperm (v = 0.2 mm/sec)
Re = 0.03

- inertia/turbulence nonexistent
- like swimming through liquid tar
- start/stop instantaneously

Scale effects in terrestrial animals

- surface increases as square while
- volume increases as cube
- big animals require greater

respiration
circulation
thermal regulation (cooling off)

support from legs (fig. 31-10, p. 652)

- muscles of small and large animals

same force per x-sectional area
grasshopper carries 50x its weight
leap many times their height
horse could not carry its own weight
chipmunks run in crouched posture
elephants need their legs underneath
largest dinosaurs had fat legs

Ameboid locomotion

- many protists
- internal ameboid cells

Gel-like ectoplasm
surrounded by more fluid endoplasm
pseudopodia develop
endoplasm flows in
becomes semi-rigid ectoplasm at tip
involves actin/myosin/ATP
similar to muscle contraction

Cilia and flagella

- ultrastructure identical
- cilia short and in clusters
- flagella long and single or paired
- found in all animals except arthropods
- can move animal through water
- or move water over animal
- but always at low Re

Fluid (hydrostatic) skeleton

- most widespread type
- fluid is sealed within tissues
- tissues can also be used for skeletons
- total volume must remain constant
- reduction in one region causes a compensatory enlargement
- usually two or more layers of muscles at different orientations

Rigid skeleton

- complement/replace fluid skeletons
- durable, strong, fossilize easily
- exoskeletons - secreted by ectoderm
- endoskeletons - secreted by mesoderm
- can be entirely organic -

chitin is a tough polysaccharide (can be cross-linked with proteins)

- others mineralized

calcium carbonate - molluscs, etc.
calcium phosphate - vertebrates

Rigid skeleton (limbs)

- muscles act against skeleton
- this action converted to movement
- restretched by antagonistic forces
- others use elastic structures
- most muscles have discrete origin, e.g., biceps - on scapula
- most muscles have an insertion, e.g., biceps - on radius

flexors and extensors: extend across joint
protractors and retractors: ant./post. movement of limb
adductors and abductors: part moved toward/away

- other muscles interlaced, e.g., snail foot, gut wall muscles
- some muscles "quick,"e.g., rapid shell closing in clams
- others "catch," e.g., used for holding shell closed

I. Integument among Various Groups of Animals

Key Terms:

II. Skeletal Systems (in part)

Key Terms:

III. Animal Movement (in part)

Key Terms:

Click link to return to Lecture Schedule
or back to Chapter 6
or ahead to Chapter 7 (under construction)