Theme 3 Animals

Question 1

Aquatic animals on land?

Answer 1

They dry out

They cant hold up their body weight

Question 2

Requirements for terrestrial life?

Answer 2

• Desiccation resistance (reduce water loss/ replace lost water)
• Desiccation tolerance (aestivation, life cycle)
• Internal bulk flow of fluids and gases
• gas exchange with air (internalized, avoid desiccation)

Question 3

Example of animals reducing water loss?

Answer 3

Concentrated urine

Longer loops of henley in the nephron

Question 4

How to replace lost water(terrestrial animals)?

Answer 4

Metabolic water
C6h12o6 —-6co2 + 6h2o
Extremely important for some animals

Question 5

Aestivation

Answer 5

Way to deal with desiccation (desiccation tolerance)
An animal goes into a state of dormancy when there is not enough water
Only some animals can do this
Metabolism slows

Question 6

Rotifer life cycle

Answer 6

Method of desiccation intolerance
Life cycle modification
Lots of water-all female clones
-diploid eggs- making diploid adult clones
Dryer environments- females start to produce haploid eggs- can hatch into a full haploid male without ferilization- this male can make sperm to fertilize other eggs-makes a 2n zygote that is desiccation resistant. When water comes back zygote hatches into adult female

Question 7

Internal bulk flow of fluids and gases-requirement for terrestrial life

Answer 7

Cardiovascular systems, blood vessels

Question 8

Mechanisms for animals to exchange gases with the air?

Answer 8

Fish suffocates in the air, its gas exchange function only works in water. Terrestrial animals need breathing systems that will work in air and that wont dry out.
Gas exchange structures become internalized (lungs)

Question 9

Insect tracheal system- example of gas exchange with air for requirement for terrestrial life

Answer 9

Series of air filled tubes that permeate air throughout the insects body. Spiracles(opening at the body surface) exchange gas with the environment

Question 10

Other requirements for terrestrial life..

Answer 10

Protect gametes from desiccation

Protect embryo for desiccation

Temperature extremes

Excretion with limited water loss

Constraints on sensory systems

Support body weight

Question 11

How to protect gametes from desiccation( requirement for terrestrial life)

Answer 11

Aquatic organisms use external fertilization

Terrestrial use internal

Question 12

Protect developing embryo for desiccation

Answer 12

Amniotic sac- amniotes have solved the problem- birds,reptile mammals
-thick skin covers aquatic larvae

Question 13

How do terrestrial animals avoid or tolerate temperature extremes?

Answer 13

Avoid- behaviour, make own heat

Tolerate- insects

Question 14

Who are terrestrial animals?

Answer 14

Very few
Arthropods and some vertebrates
Insects,arachnids,myriapods, amniote vertebrate
Why so few?(requirements for terrestrial)
-desiccation resistance 
-desiccation tolerance
-internal bulk flow of fluids and gases
-gas exchange with air

Question 15

Excretion of ammonia, terrestrial challenge

Answer 15

Ammonia is an end product of metabolism
It is toxic, cannot accumulate, how to get rid of it without loosing a lot of water
Aquatic organisms use diffusion
Terrestrial organisms convert ammonia into urea so it can be concentrated in their bodies
Some terrestrial organisms convert ammonia into uric acid instead- low solubility in water- uric acid crystals

Question 16

Excretion of ammonia in an egg

Answer 16

Uric acid crystals (precipitates
As a solid) low toxicity
Doesnt waste water

Question 17

Constraints of sensory systerms

Answer 17

Need to work in air

Chemo and mechano

Question 18

Mechanosensors for terrestrial

Answer 18

Vibrations
Insects have tympanum, - dont have the challenge of moving vibrations from air to liquid
Vertebrates- middle ear, inner ear is liquid
- middle ear bones link the ear drum

Question 19

Terrestrial problem, support body weight

Answer 19

Robust skeleton

Sa/v relationships

Question 20

Sa/v relationship to support body weight

Answer 20

Sa/v dictates that the limbs(support SA) must change disproportionately to body size(Volume and mass) as animals get larger
In terrestrial if it was linear, body mass would exceed limb ability
-impossibly big animals
Not a prob in water b/c water supports body mass

Question 21

Stance changes to support body weight of terrestrial environment

Answer 21

Sprawling-small animal
Erect
Pillar-erect

Question 22

Aquatic animals advantages

Answer 22

Water supports body
-affects stance and skeletons

Desiccation is a lesser threat
Stable and mild temps
Metabolic waste removed by water
Sound transmits well from water to body

Question 23

Terrestrial vs aquatic skeleton

Answer 23

Terrestrial have thick robust limbs
Terrestrial animals have to hold organs off the ground- robust ribcage
Aquatic animals can have free floating ribs

Question 24

Challenges of living in water

Answer 24

Water is dense
Water is viscous
Water has low oxygen content
Water has high thermal conductance

Question 25

Water is dense and viscous

Answer 25

Water is heavy, can hold animals up

But if you are trying to move through it it takes energy, also because it is sticky

Question 26

Why is being warm in aquatic environments hard?

Answer 26

Animals that have not moved from terrestrial–> aquatic don’t warm their whole bodies up.
Low oxygen and high thermal conductance
If you breathe water, don’t have enough energy(oxidative metabolism) to make heat
Water has high t conductance( draws heat out of things )

Question 27

Respirtory medium

Answer 27

If some marine animals breathe air it helps them warm their body up because breathing air gives them more energy that breathing water

Question 28

Countercurrent heat exchanges

Answer 28

Aquatic organism cant warm their whole body up
This is a mechanism to conserve heat
Help keep heat down inside the core by having two vessel side by side, transferring heat between each other, always transferring the heat from the vessel going to the body surface/ gills to the vessel that goes towards the core.