BIOL 371-Theme 3 Animals

Where did animals originate? How did they come on land?

Terrestrial animals came from the ocean, and they came on land INDEPENDENTLY.

Terrestrial environments provided...

Many evolutionary opportunities -Like: new resources, less competition ect.

Conditions on land that are different from aquatic ones: (4)

1. Gravity: have to maintain posture and locomotion.

2. Air: can obtain oxygen, as it is much less dense than water - Locomotion, sensory modes and thermal properties are affected by difference in density, light, sound, movement and heat works differently in air than in water

3. Water: always a limiting resource on land as individuals need to find water recourses to live

4. Sunlight: different exposure to UV radiation.

What are the requirements for an animals to be able to live on land? (6)

1. Desiccation avoidance (prevent water loss): This can be avoided in two ways, avoid water loss or replenish lost water

2. Desiccation tolerance: causes different life cycles (kind of like dormancy)

3. Excretion with limited water loss: must be able to get rid of nitrogenous waste (toxic) without loosing to much water

4. Gas exchange with air: Must have internalized gas exchange organs (lungs) to avoid desiccation and to be able to breath (lung are wet, and you loose water when you breath)</

5. Internal bulk flow of fluids and gases: Pull air in and circulate extracellular fluid (gravity has effect)

6. Gas exchange with air: Internalized gas exchange organs

All terrestrial animals are constrained to...

the availability of water

What are some ways terrestrial animals loose water?

1. Evaporation: due to wet respiratory membrane (lungs) and across surface of skin (sweating)

2. Urine and Feces

3. Thermoregulatory method: Sweating and panting (just increases number 1)

In animals like turtles, what are some ways that desiccation is prevented?

1. Waterproofing of the out layer of the body (through the use of keratin or wax)

2. Ensuring gas exchange organs (lungs) and digestive systems have MINIMAL exposure to external environments (INTERNAL PLACEMENT)

3. Gain of metabolic water (source of water)

What are nitrogenous wastes?

TOXIC ammonia (NH3) produced by EVERY cell of the body, through the (break down) catabolism of amino acids and nucleic acids.

Three types of animals do something special with nitrogenous wastes, what are the animals and what is the mechanism?

Reptiles, birds and insects. They convert ammonia (NH3) to uric acid Uric acid: Low water solubility, semi-solid nitrogenous waste, that can be excreted with MINIMAL WATER LOSS (conserve water)

When talking about excretion in mammals, what are their characteristics? (3)

1. Ureotelic: Convert ammonia (NH3) to less-toxic urea, however, water is lost during excretion

2. Loop of Henle: aids in conservation of water as it pulls water into cells (has high permeable spots and low permeable spots to water) - Longer loop of Henle= more water conservation

3. Concentrated Urine: HYPERosmotic to blood (more solutes than blood)

What are important traits of a kangaroo rat with regards to water conservation?

1. Desert adapted rodent (used to low water resource)

2. LONG loop of Henle

3. Produces small quantity of very HYPERSOSMOTIC urine

4. Have plenty of metabolic water (dont drink much water, mainly get water from metabolic water and food)

How do insects deal/problems with desiccation? (3)

1. Have a small size, and therefor, a large surface area - Cube squared relationship FAVOURS water loss through evaporation, and through wet respiratory surfaces in the trachea

2. They have a waxy layer on the outside of cuticle that MINIMIZES evaporation from body surface

3. SPIRACLES permit closing of TRACHEAL system, to cut evaporative water loss

What animals have dessication tolerance? Explain their mechanism.

Terrestrial Tardigrades - live in damp envionrnments (water films)

a) Cryptobiosis: Fomration of resustance stage (tun) due to environmental challenges (dehydration, freezing temps)

b) Ahydobiosis: When dessicated, resistance tun formed, when rehyrdated, tardigarde returns to active state.

Explain the rotifer life cycle (unstressed and stressed environment) -Detailed

Unstressed:Adult female (2n) repoduces by parthenogenisis (lays cloned eggs -2n), to keep population going. No males.

Stressed: Adult female (2n) produces eggs (n) by meiosis, which grows to become male that makes sperm (n) to reporduce sexually with the female. Resulting zygote (2n) is dessication resistant. Will wait till water is available until hatch into diploid females.

Rotifer Life cycle - Summary

Bad Environment - Make haploid individuals (males are there)

Good Environment- Make diploid individuals (only females)

What is aestivation?

Prolonged period of DEPRESSED metabolism to avoid drought and heat.

Many organisms will live completely underground (low heat plus damp), or may release a cocoon where only nostrils are open (and be burried)

Can be burried for 2 years Ex. Desert dwelling frogs

What are disadvantages of breathing air?

CO2 does not diffues into air as easily as into water, therfore, CO2 is hard to get rid of evaporation

water loss from internal respiratory system (it is wet, whenever you breath you loos water)

What are the advantages of breathing air?

1. Greater oxygen content than water (21%)

2. Atmospheric O2 diffuses more rapidly across respitory system<br>3. Bulk flow of air (ventilation) requires less muscular effort due to low viscosity and density

Desribe the insect trachea system

Delivers air DIRECTLY to tissues by the interstitial fluid.

The exhange surfaces are internal and moist -Form of bulk flow system but for air.

Describe the gas exhange system of vertebrates (humans).

Bulk flow of air to respiratory membrane (lungs), and mosit exchange surfaces allow gas exchange. Requires musuclar effort (ventilation/breathing)

There are 5 more requirenments for terrestrial life, what are they?

1. Protect gametes from dessication: internal fertilization without water

2. Protect embryo from dessication- -Aquatic larvae- thick covering on egg/embryo -Amniote vertebtarte (birds/mammals/reptiles): amniotic membrane

3. Temperature extremes: Avoiders (thermoregulation) and tolerators

4. Constraint of sensory systems: Chemosensors and mechanosensors (tempanal organ and middle ear)

5. Support body weight (fight gravity): Robust skeleton, cube-squared relationship and body size/stance

Desribe the reproduction of amphibians

Lay AMNIOTIC eggs in water, so the embryos can exchange gasses and wastes with aqautic environment.

Adult form lives on land.

What is the amniotic egg? What are the requirnments? (vertebrates)

Provides an aqeuous enviornment for the developing embryo.

Must develop through INTERNAL FERTILIZATION, and through an uricoley.

Endoembryonic membrain support the developing embryo as the shell is still porous to air and possibly water.

What is thermoregulation?

The regulation of internal body temp in response to external change in temp

Why is thermoregulation important? (for terrestrial animals)

Terrestrial animals can regulate body temperature when possible through metabolic activity or behaviour. (Animal body range 4-40 degrees)

Why is thermoregulation nessesary in low temps or extremes?

When it is very cold, formation of ice crystals in the cells can cause them to die.

Enzyme effectivness is dependent on temp (and pH), when very cold, active site may change shape and therfore, may loose its ability to catalyze metabolic reactions.

In really high temps proteins denature and there is no coming back from it.

Why are biochemical processes important in regards to thermoregulation?

Performance is dependent on them, and animals regulate body temps to allow for optimal performance.

What are the 4 ways of thermoregulation?

1. Endothermy (warm blooded): Production of sufficient metabolic heat to warm tissue

2. Ectothermy (cold blooded): Insufficient heat produced by metabolic activities to warm tissues, HEAT MUST BE EXCHANGES WITH ENVIRONEMNT (cant generate enough heat to stay warm)

3. Heterothermy: Allow body temp to vary

4. Homeothermy: Regulate body temp around varrying average

What are endotherms?

Metabolic rate changes with temp inorder to maintain a constant body temp

They expend energy inorder to maintain temp, but they can physically stay active over higher range of temp

ENERGETIC COST, LITTLE LIABILTY

What are ectotherms?

Metabolic rates changes DIRECTLY with body temp due to a change in external temp.

This allows very little energetic cost (as temp flucutuates with little regulation), but has a liability as animals will not be active for a large range of temp (very hot/cold)

LOW ENERGETIC COST, HIGH LIABILITY

What are the 4 ways to exchange heat with the environment?

1. Conduction: Direct heat transfer by CONTACT - Air is a poor conudcutor, water is a good one (aquatic organisms tend to be isothermic with the water)

2. Radiation (common in ectotherms): Transfer of heat as a long-wave light (due to sun), not a great way to loose heat.

3. Convection: Transfer of heat due to wind/water (moving air/water) over an organism to carry heat (air is good)

4. Evaporation: Loss of heat through sweating but causes a loss of water

Desbribe the heat exchange of an ectotherm

They regulation their heat by convection, radiation, and conduction and sometimes evaporation.

A basking lizard regulates temp by sitting outside on hot rock (conduction) in the sun (raditaion) and is warmed by wind (convection).

METABOLICALLY CHEAP

What is the countercurrent heat exchange system?

Endotherms keep core temp up.

Cold climate endotherms conserve heat by countercurrent heat exchange structures.

Warm blood in efferent vessels (away from heart) warm blood in vessels that come from afferent vessels (from example paw)

This is regional heterothermy (different parts of body vary in temp) What is torpor?

Reduces energy demands by depressing metabolism in small endotherms dring period of high or low temps (or due to resource unavailibility)

Body temp SET POINT drops

Can be woken up, happens on a regular bases

What is hibernation?

A seasonal version of topor but much more extreme

During period of low temp, animals will have a depressed metabolism and ""sleep" -Cannot be woken up

Describe endothermy in insects

Heterothermic endotherms: Generate heat due to flight muscles which maintain a constant high temp in thorax

These insects tend to be furry

What is freeze avoidance?

Some ectotherms can SUPERCOOL their extraceullular fluid (blood) - marine animals Causes freezing point depression due to salt

What are freeze tolerators?

Some terrestrial ectotherms can allow the bulk of their extracellular fluid (ECF) to freeze for extended periods.

The high osmolality of the intracellular fluid (high solute) depresses the freezing point.

This allows a control of ice nucleation (freezing up cells which causes the cell membrane to rip) in the ECF.

Which is better for carrying chemical signals, water or air?

Water

Does air or water transmit the following better: Light, chemical signals, sound

Light: Air tramsits light better

Chemical Signals: Water conveys chemical signals better

Sound: Speed of sound is greater in water

What is an important sense that is important in terrestrial animals and no so much in aquatic ones?

Being able to know which way is up/down. Prevents falling to death

What are chemosensors? (terrestrial)

"Chemosensory organs that require wet surfaces for absorption of air-borne chemicals to ""read" them

What are examples of chemosensors in insects?

Antennae- minute channels lines with wet absoprtive tissue

What type of chemosensors do terrestrial vertabres have?

Moist olfactory epithililium in the oral cavity (taste buds)

How do insects hear?

Have a TYMPANAL ORGAN (TYMPANUM) where air on either sides is picked up by nerves called mechanoreceptors.

These rely ENTIRLEY on the mechanoreceptors.

How to vertebrates hear/balance?

Have organs for hearing, sensing acceleration, and which direction is down (vestibular labyrinth in inner ear)

How do fish hear?

Have inner ear that can pick up vibrations through the tissues (same as tetrapods/amphibians)

In fish, hyomandibular bones suspends lower jaw.

How to tetrapods hear?

Middle ear transforms large-amplitude ear drug vibrations to low-amplitude/high-force vibration which are transmitted to oval window of inner ear This amplifies the vibrations so that waves are produced in the fluid-filled cochlea

What is a force that terrestrial organisms are subject to?

GRAVITY

Volume (mass) is a function of....

(linear dimension)^3

Cross-sectional area of a limb (support and strength) is a function of...

(linear dimension)^2

As an animal gets bigger, body mass (increase/decrease) faster than the cross sectional area of the limbs.

INCREASE

What would be a problem is body and limbs scale (grow) proportionally/lineraly with mass?

Body mass = linear^3 Therefore, body mass would exceed ability of limbs to support it

How to limbs grow with respect to the body size/mass?

Allometrically- limbs must grow disproportionatley to body size as the animal grows

What animals are free from the contraint of allometric growth?

Aquatic organisms

What is allometry/differential growth?

A characteristic of most animals where different parts of body grow at different rates with an overall increase in size.

It is an evolutionary phenomenon assosiated with increasing or decreasing body size in a lineage.

What would the graph look like for allometric growth?

NOT LINEAR GROWTH

An example of allometry is the humerus in Varanus V. komodoensis: Describe

As the lizard gets bigger, the humerus thickenss faster than the increase in body size (positive allometry)

Inorder for limbs to support body mass, how must they grow?

allometrically

Posture also has an affect on being able to support body weight. What are two configurations of posture?

Sprawling limb: Normally in ectotherms as it takes less energy to maintain

Erect limb: Normally in endothermy, support weight more efficiently.

What the two types of hard skeletons (found in aqautic and terrestrial animals)?

1. Exoskeleton: An external skeleton

2. Endoskeleton: An internal skeleton (like ours)

What are the 5 functions of a hard skeleton?

1. Provide attatchments and levergage for muscles (force transmission)

2. Trasmit compressive stress to substrate (legs) to support body

3. Provide a frame work for tissues

4. Provides minerals for physiological requirnments in vertebrates

5. Protects organs and whole body

What are endoskeletons? What are the 3 features?

In vertebrates- composed of bones and cartilage
Bone: collagenous matrix mineralized by CaPO4 crystals -Highly vasularized, and the matrix build supports scattered oseocytes (bone cells) Metabollically active Bears compressive stress well (direct stress not so much, hence bone breaks)

What are exoskeletons (in arthropods)? Important of tergae?

Consists of a chitin (complex polysacharaide to be impregnated with calcium bicarbonate) - strong shell like structure

Composed of plates called tergae with joints Tergae:Mark the segmentation of limbs and body Limb joints are mobile

Muscles are within the skeleton anchored to the tergae (plates)

What are hydrostatic skeletons?

Volume of a fluid that is enclosed by 2 layers of muscles (logitudinal and circular)

The fluid is incompressivle but pressure is added when the muscles contract

The musuclar strucutre is abe to change shape with the contraction of different muscular layers Can be an organ or the whole body

What are the 5 advantage of being an aquatic animal?

1. Water supports the body (can grow larger)

2. Dessication is not as likley

3. Stable and mild temp (water temp is much harder to change drastically- high thermal intertia

4. Metabolic waste is removed by water

5. Sound transmits well from water to body (due to density)

What are the 4 challenges of being an aquatic animal?

1. Water is dense (energy required to move through)

2. Water is viscous (layer cling to body- larger affect on small organisms)

3. Water has low oxygen content (1-2%)

4. Water has high thermal conductance (loose heat to water easily)'

Are the biggest aquatic animals air/or oxygen breathers?

Air (from atmosphere due to higher oxygen content -21%)

What is a problem with being a marine tetrapod? (in regards to salt) How is this solved?

Marine environments are very salty

Birds-The excsess salts is exctreted through salt glands whcih are assosiated with the upper resiratory tacts or eyes.

Or mammals extrete a HIGHLY hyperosmotic (salty) urine

What is the heat regulatroy mechanism that most aquatic organisms use?

Heterothermic ectothermy (temp is changed by external temp), and this is becasue water is a good heat conductor.

How do aqautic homethermic endotherms be warm in aqautic envronments?

Have an isulation layer that is either blubber, fur, feather (water proof pelage)

Why do a lot of big aquatic organisms breathe air?

Allows for higher metabolic rate

What type of heat exchange system to aquatic endotherms use?

Counter-current heat exchange, to allow outbound blood to heat inbound blood to reatin heat (maintains gradient along an organ)

What is a belime?

Filters food partials when whales swallow cold water.

Cold water must be regulated via coutner-current heat exchange

1. What is the diffrence between terrestrial and aquatic endoskeletons?

Terrestrial- very tightly articulate

Aqautic- ribcage not encolsed, the girlde (holds limb to spinal cord) is loosley attactched