ecology exam 2 ch 7

how do larger organisms acquire oxygen?

*cannot use direct diffusion across the body surface - insects have spiracles (openings) on the body wall that lead to tracheal tubes that carry oxygen into the body - terrestrial vertebrates have lungs that allow oxygen to diffuse into the bloodstream that carries it to the cells (some amphibians also use moist vascular skin) *Frogs bury themselves in the winter and rely on O2 coming thru skin

Omnivores eat both plants and animals:

*diet may highly variable *can vary with the seasons; stages in the life cycle, size, and growth rate - red foxes eat berries and grasses, some insects and small rodents - black bears eat mainly vegetation, including buds, nuts, tree bark, and supplement with insects, fish, and small to medium mammals - frogs usually eat algae as tadpoles and insects as adults

homeotherms & SA/V ratios

- The smaller the organisms (larger SA/V ), the greater the relative heat loss to the surrounding environment - This heat loss must be offset by increased metabolic activity

freshwater bony fish are osmoregulators:

- They drink very little water - Produce large amounts of dilute urine - They take up sodium and chloride ions by pumping them across their gills; active transport is energetically expensive

freshwater animals are hyperosmotic, meaning what?

- They have a higher salt concentration in their bodies than the surrounding water. - The water flows into their bodies from the environment.

key processes that animals share include:

- acquiring and digesting food - absorbing oxygen - maintaining body temp and water balance - adapting to daily and seasonal environmental changes

some aquatic animals must surface for oxygen:

- aquatic insects have a tracheal system and surface to fill it with air - aquatic turtles and mammals have lungs

animals regulate body temp through:

- behavior - physiology - morphology

how do terrestrial animals gain water?

- directly through drinking and eating - indirectly through cellular respiration and the production of metabolic water

carnivores eat other animals:

- do not have problems with food quality or digesting cellulose - do not have problems digesting and assimilating nutrients from prey because the chemical composition of the tissues is similar - quantity is important: they must be able to find enough food - many eat herbivores

scaling

- geometrically similar objects are isometric - surface areas (SA) and volumes (V) of isometric objects are related to their linear dimensions (SA:V ratio diff for large vs small animals)

costs of endothermy:

- higher metabolic rate requires more calories per gram of body weight (more food) - small endotherms must eat almost constantly - why? - usually allocate more energy to metabolism than to producing biomass - producing insulation

benefits of endothermy:

- homeotherms can remain active even if environmental temperature varies - maximum body size is not constrained because heat is generated internally - large endotherms can live in cool environments

Wikelski also studied the effect of El Nino events on iguana populations:

- increase in sea surface temps and disruption of nutrient upwelling - disappearance of red and green algae (preferred by iguanas) and appearance of hard-to-digest brown algae - high iguana mortality during El Nino (related to foraging efficiency which is related to body size)

Characteristics of poikilotherms include:

- low metabolic rate - high thermal conductivity - aerobic respiration during normal activity - under increased activity and stress, most energy is produced anaerobically (depletes stored energy; lactic acid accumulates in muscles)

benefits of ectothermy:

- lower metabolic rate requires fewer calories per gram of body weight (less food) - can allocate more energy to producing biomass than to metabolism - can reduce or curtail metabolic activity when food or water is limited, or environmental conditions are extreme - can live in environments where food and water are limited

describe oxygen in aquatic environments:

- may be limiting - may be problematic to acquire - may be taken from the water or from the atmosphere

environmental variation occurs across a wide range of timescales:

- some changes are regular, others are less predictable - an animal can respond to environmental changes in two diff ways: conform or regulate

costs of ectothermy:

- temperature of the environment determines activity - maximum body size is constrained because heat is absorbed across the body surface (surface/volume ratio becomes to low for heat to warm the entire body mass; larger ectotherms can live in only in warmer environments)

marine fish are hypoosmotic, meaning what?

- their tissues have a lower solute concentration than the surrounding water - the water flows out of their bodies into the environment

how do terrestrial animals lose water?

- urine and feces (water is reabsorbed across the cloaca in sauropsids; mammalian kidneys can reduce water loss) - evaporation from the skin - exhaling moist air

The surface area of a cube increases how in relation to its length (l)?

6l^2

Which of the following factors does not influence animal heat exchange? A. oxygen diffusion rate B. fat thickness C. conductivity of fat D. movement of blood to the body's surface

A. oxygen diffusion rate

Which of the following is a major problem for animals that live in hyperosmotic environments? A. preventing water loss B. obtaining enough oxygen C. access to mineral nutrients D. preventing heat loss

A. preventing water loss

What are homeotherms?

Animals that maintain a constant, or nearly constant, internal body temperature

Which of the following is an example of a conformer? A. lizard B. bird C. starfish D. rodent

C. starfish

_________________________ __________ _______________can conserve heat in a cold environment or can cool vital parts of the body under heat stress

Countercurrent heat exchange *keeping heat in - The porpoise maintains body core temperature by exchanging heat between arterial and venous blood

Animals in arid environments face a severe problem of water balance and deal with the problem in several ways:

Evade drought - Leave the area during the dry season - Enter a state of dormancy or diapause - Develop a hardened (watertight) casing Evade the effects of drought - Reduce respiratory water loss - Nocturnal activity - Utilize metabolic water

how do minute organisms acquire oxygen?

by diffusion

_________________ are those that feed on detritus (dead plant and animal matter)

detritivores

are homeotherms and poikilotherms synonymous with conformers and regulators?

NO

Maintaining a consistently high body temperature requires what?

Requires efficient respiratory and cardiovascular systems to provide oxygen to tissues and allows homeotherms to: - sustain activity for long periods of time - live in a wider range of thermal environments - generate energy rapidly when needed

a _______ is a vascular bundle or net composed to arteries and veins divided into small, parallel, intermingled vessels

Rete *Countercurrent exchange occurs when blood flows in opposite directions through these parallel vessels * Can be used to cool or heat - the desert oryx cools its brain with a rete in its head - some fast swimming fish use a rete to warm muscles used for swimming

why must small endotherms eat almost constantly?

Small size means larger surface to volume ratio - more heat is lost to the environment Heat loss is offset by increased metabolic rate - small shrews eat about their wet body weight in food each day Size limit of about 2 g on endotherms - some shrews and hummingbirds fall below this by undergoing torpor daily to reduce metabolic needs

Why aren't freshwater animals osmoconformers?

The difference between the osmotic concentrations of freshwater and body tissues is too great

Birds and mammals produce heat through what process?

aerobic cellular respiration - this process is not 100% efficient - energy is lost as heat

Animals, like plants, use ___________ ________________ to covert the energy in organic compounds into energy that cells can use

aerobic respiration

Animals that live on the land need to be able to cope with a greater range of temperatures because __________.

air is more susceptible to temperature change than water

benefits and costs of regulation:

benefits: - greatly extended range of environmental conditions for activity, growth, reproduction and increased level of performance costs: - usually energetically expensive

benefits and costs of conformity:

benefits: - low energetic expenditure - mechanisms to maintain a consistent internal environment not needed costs: - if environmental conditions are not optimal, it can lead to reduced activity, growth, reproduction

examples of endothermic homeotherms:

birds and mammals (these animals have a high metabolic rate) * all other animals are typically considered to be poikilotherms

Some marine animals are isosmotic (osmoconformers), meaning what?

body fluids have the same osmotic pressure as the seawater ex: tunicates, jellyfish, many mollusks, sea anemones

most morphological and physiological features change as a function of:

body size (in a predictable way)

What are poikilotherms?

body temperature varies directly with environmental temperature (variable body temp)

____________________ feed exclusively on the tissues of other animals

carnivores

grazers and browsers usually have high diets very high in ______________

cellulose (long chains of glucose molecules) - rich in carbon, low in protein - most animals do not produce enzymes that can digest cellulose - have mutualistic bacteria and protists living in their digestive tract - these symbionts: digest cellulose and proteins; synthesize fatty acids, amino acids, proteins, and vitamins

Heat is transferred through an animal, from its core to its surface, through __________.

conduction

in __________________, changes in the external environment cause parallel changes in the body

conformers - unable to maintain consistent internal conditions that are different than the external environment (solute concentration, oxygen concentration) - starfish (an echinoderm) living in marine environments is a conformer

Water flows over gills in the opposite direction of blood flow in a process known as:

countercurrent exchange.

as the size of an organism increases, the surface area _____________(increases/decreases) relative to interior body volume

decreases *this constraint may be overcome by a body plan that somehow can increase surface area in another way: - change shape to increase external surface area - actively transport oxygen into the interior of the body and increase internal surface area (ex: lungs, circulatory system)

minute animals, often part of the zooplankton, take up oxygen by ____________

diffusion

animals feed on many different types of organisms; this leads to a ___________ of adaptations among animals

diversity

what can help keep blood pressure up?

drinking water

The regulation of body temperature exclusively from the external environment is referred to as ________________

ectothermy

________________ is the process of maintaining body temperature through exchange of thermal energy with the surrounding environment

ectothermy

example of animal with extremely low SA/V ratio and how they maintain constant body temp:

elephants would have hard time keeping that low SA/V cool; may be hot because too much body heat *adaptations= large ears

_______________ is the process of maintaining body temperature through internally generated metabolic heat

endothermy

Poikilotherms use mainly behavioral thermoregulation by seeking out appropriate microclimates; how do they do so?

environmental temperatures allow near optimal body temperatures - bask in the sun to warm - rest in the shade to cool

how do homeotherms reduce body temp?

evaporative cooling - moisture evaporates from the skin and heat is lost - when body temperatures is above the upper critical temperature (panting and sweating accelerate evaporative cooling; birds use gular fluttering; some animals wallow in water or wet mud)

most larger aquatic animals have ________

gills - vascular outfoldings of the body surface that are in direct contact with the water and exchange gases - some gills are simple and distributed over the body - some gills are complex and restricted to a specific region

herbivores are categorized by the type of plant tissues they eat

grazers- eat mainly leaves, especially grasses (rabbits are grazers) browsers- eat woody material, some leaves/grass (deer are browsers) granivores- eat seeds (ex: birds) frugivores- eat fruit

what type of feeder is a marine iguana?

herbivore- feeds on intertidal and subtidal algae (algal growth correlates with sea surface temp) - Wikelski demonstrated that algal availability affects iguana growth rate which affects iguana body size

_________________ feed exclusively on plant tissues

herbivores

____________________ is the maintenance of a relatively constant internal environment in a varying external environment

homeostasis *this depends on negative feedback - whenever conditions deviate from the normal state, the set point, mechanisms engage to restore the system to that state - a thermostat that controls the temperature in a building is an example of a negative feedback system

The term _____________________ is usually applied only to animals that can maintain a constant body temperature through metabolic processes, endotherms

homeotherm

_________________ regulate body temp thru metabolic processes

homeotherms

what is an example of a negative feedback system?

human body temp regulation - set point for human body temp (the variable) is 37 degrees C - If environmental temperature increases, receptors in the skin detect this and send a message to the brain (the integrator), which relays messages to receptors (effectors) that increase blood flow to the skin, induce sweating and behavioral responses that cool the body - If environmental temperature decreases, another reaction takes place, reducing blood flow and causing shivering (muscle contractions that produce heat) - If environmental temperatures are too extreme, this system breaks down and heatstroke or hypothermia may result

a convoluted surface _____________(increases/decreases) the surface area of the organism

increases *altering shape is one way to increase the ratio of the surface area to volume ratio for an object of a given size

what does a conformer's ability to survive depend on?

its ability to survive environmental changes depends on its range of tolerance to internal changes

a shrinking of marine iguana body length coincided with what?

low food availability resulting from El Nino events - larger individuals "shrank" less than smaller individuals - those large individuals that shrank more survived longer

what type of animals are typically oxygen conformers?

mainly sedentary marine invertebrates such as cnidarians and echinoderms

Many marine organisms are osmoregulators....

marine bony fish - they drink water and absorb it into their gut - produce small amounts of concentrated urine - they excrete sodium and chloride ions by pumping them across their gills; active transport is energetically expensive

Field studies: Martin Wikelski (princeton university)- examined the relationship btwn iguana body size and food supply:

marine iguanas are widely distributed throughout the Galapagos Islands - populations (of the same species) vary dramatically in size (length and weight) - this conformer attempts to regulate - no other iguanas are marine - regulating via behavior

negative or positive feedback: 3. A dog pants as it lies in the hot summer sun, releasing excess body heat to the environment and lowering its body temperature to its stable state.

negative

_________________ feed on both plant and animal tissues

omnivores

some herbivores are specialized:

plant sap- birds, insects (aphids) nectivores- hummingbirds, butterflies, bees

________________ Regulate Body Temperature Primarily through Behavioral Mechanisms

poikilotherms

negative or positive feedback: 2. Increasing air temperatures from global warming speed up the melting of glaciers, exposing darker rocks underneath the ice. The dark surfaces absorb more sunlight, causing further increases in temperature and accelerated glacier melting.

positive

negative or positive feedback: 4. A bull on the edge of a herd of cattle panics when it hears a loud noise and begins to run. Five nearby cattle sense the panic and also begin to run. This causes another 15 cattle to panic. Eventually, all 100 cattle in the herd panic and stampede.

positive

negative or positive feedback: A snowball rolling down a hill accumulates snow and becomes larger, which increases its speed, causing it to increase its size and speed even more

positive

in _________________, changes in the external environment do not cause internal changes

regulators - able to maintain consistent internal conditions that are diff than the external environment over a broad range of environmental conditions - regulation may be: biochemical, physiological, morphological, behavioral

morphological and physiological features change as a function of body size, a process known as ___________

scaling * size has consequences for structure and functional relationships in animals

example of animal with extremely high SA/V ratio and how they maintain constant body temp:

shrews would have hard time keeping that high SA/V warm; may be cold because they lose a lot of body heat *adaptations= they eat 3-4 times their body weight everyday in order to maintain constant body temp

_____________ (Smaller/larger) organisms have a larger surface area relative to volume than do ____________(Smaller/larger) organisms of the same shape

smaller, larger

describe how brown fat is utilized?

some small mammals burn brown fat, which has many more mitochondria and generates more heat (found in hibernators such as bats and groundhogs)

Maintaining a consistently high body temperature includes what?

specific enzyme systems that work best at a high temperature range - set point about 40 degrees C

what can size impact?

structure/function relationships in animals

how are surface area and volume related? for a square:

surface area = length x length (length squared) * a square does not have volume

how are surface area and volume related? for a cube:

surface area= 6 x length squared volume= l x l x l= length cubed

Many grazing herbivores, such as cows, can eat poor-quality plant material because __________.

the bacteria in their stomachs digest the cellulose and synthesize additional nutrients

what is basal metabolic rate measured by?

the rate of oxygen consumption

Only true ____________________ are animals that live in environments with almost no variation in temperature such as the deep ocean

thermoconformers

most organisms are oxygen regulators; what does this mean?

they are able to maintain normal oxygen consumption levels even when external oxygen levels drop below normal

problems for conformers arises with extreme temps:

they basically have to shut down and go into survival model; a lot found in water where environment more constant; a lot in more tropical consistently warmer environments

describe the components of a feedback loop:

variable- focus of the regulation receptor- measures the internal environment for the variable and transfers the info to the integrator integrator- evaluates the info from the receptor and determines actions that need to be taken by the effector effector- functions to modify the internal environment (variable that is the focus of regulation)

as the size of a cube increases, does volume or surface area increase more rapidly?

volume increases more rapidly than surface area as the size of a cube increases