Basic Life Processes and Classification

What percent of all known animals are invertebrates?

98%

Which subphylum is the only one that includes vertebrates?

chordates

morphological plasticity

close related species look and function differently (due to niche)

Where do most invertebrates live?

marine environments

Why do not many groups live in terrestrial environments?

harder to adapt and survive

What do many terrestrial groups still have?

aquatic developmental stages

Advantages of the aquatic environment

1. stable physical and chemical conditions - Particularly in oceans

2. no desiccation or dehydration

3. diffusion of gases easily facilitated across moist surfaces

4. absorption of nutrients and elimination of wastes easily facilitated

5. food capture by suspension feeding is possible

6. Reproduction can be less complex

specific heat capacity

takes more energy to change 1g of water than it does air

aquatic environment daily temp fluctuations

1-2 degrees Celsius

aquatic environment seasonal temp fluctuations

15-20 degrees Celsius

Terrestrial environment daily temperature fluctuations

5-20 degrees Celsius

Terrestrial environment seasonal temperature fluctuations

35-45 degrees celsius

Why does the temperature of water fluctuate less than air?

water has a higher specific heat capacity than air

Benefits of water for organisms

water bathes internal and external surfaces

terrestrial environment organism adaptations

must prevent water loss often with mucus, waxy coatings, or complex dermis

marine organisms gas exchange

gases exchanged across body wall or external respiratory structures (ex: gills)

• no risk of drying out so gas exchange organs can be exposed

terrestrial organisms gas exchange

elaborate internal respiratory structures

Benefits of excretory processes in aquatic environment

wastes can be easily excreted and diluted in surrounding water, not in air. Water is full of dissolved salts and nutrients, air is not

how do aquatic organisms excrete waste?

toxic metabolites (like ammonia) are easily diluted and excreted. Uptake of dissolved compounds possible (important for larvae)

How do terrestrial organisms excrete waste?

requires complex excretory structures to detoxify ammonia and then excrete in concentrated form. Parents must supply all salts and nutrients to offspring

Benefits of aquatic environment for suspension feeding

water has more suspended particulate organic matter than air

How do aquatic organisms feed?

suspension feeding is very common

How do terrestrial organisms feed?

suspension feeding is not feasible, more complex structures and actions

Benefits of reproducing in aquatic environment

water is more physically hospitable for developing embryos and larvae than air

how do aquatic organisms reproduce?

broadcast spawning and external fertilization are common; parental support of offspring can be negligible

• release sperm and egg in water and they get fertilized in water

• ex: clams → larvae is mobile, adult is not

how do terrestrial organisms reproduce?

only internal fertilization is possible; internal development (in adult body or in egg) is the rule. Usually adults are the dispersers

• ex: butterfly → larvae is not mobile, adult is

Disadvantages of the aquatic environment

oxygen solubility is low - 2.5% of air

• diffusion of gases is slow

• hypoxic or anoxic conditions more likely

hypoxic

low oxygen

anoxic

absence of oxygen

Freshwater is ____ relative to invertebrates

hypotonic

hypotonic

High solute concentration inside cell, so water flows in

hypotonic cell diffusion direction

water in, salts out

Disadvantage of freshwater environments

small freshwater bodies dry up periodically

oceanic zone

waters beyond continental shelf

nertic zone

waters over continental shelf

intertidal (littoral) zone

between high + low tide

subtidal (sublittoral) zone

below low tide

pelagic fauna

animals that live in suspended water

planktonic

moved by water currents (drifters + wanders)

nektonic

can move against water currents; swim (most fish, whales, etc.)

benthic fauna

animals that live on bottom

• opposite of pelagic

• epifaunal

• infaunal

• interstitial

epifaunal

live on surface of bottom

infaunal

live beneath surface of bottom (worms, clams)

interstitial

microscopic, live between sand + grains

sedentary fauna

animals that are capable of some movement, but don’t move much

sessile fauna

animals that are incapable of locomotion

• ex: oyster

macro fauna

can be seen with the naked eye

myo fauna

squint to see with naked eye

micro fauna

can’t see with naked eye

5 basic requirements and challenges animals face

1. acquiring food and nutrients - building blocks of energy

2. exchange of gases - respiration, cellular metabolism

3. elimination of wastes and osmoregulation - ammonia + water balance

4. reproduction - continuation of one’s genetic information

5. interact with environment - movement, sensory reception

How do organisms acquire food and nutrients on cellular level?

Phagocytosis/Exocytosis

phagocytosis

ingestion

exocytosis

egestion

pinocytosis

uptake of small nutrients

How do organisms exchange gases on a cellular level?

simple diffusion

simple diffusion

gases, metabolic wastes, water balance

• soluble makes high → low concentration

how do organisms reproduce on a cellular level?

mitosis

How do organisms move on a cellular level

simple movement

simple movement

cilia, flagella, pseudopodia

• “sensory” structures are membrane receptors

How do organisms digest food on an organismal level?

digestive system - ingestion and egestion

digestive system

• breaks down complex food items

• facilitates uptake by cells

How do organisms exchange gases on an organismal level?

circulatory/respiratory systems

circulatory/Respiratory systems

• circulates nutrients to body cells

• carries gases to and from body cells

How do organisms excrete waste on an organismal level?

excretory system

excretory system

metabolic waste and water balance

• concentrates and eliminates wastes

How do organisms reproduce on an organismal level?

reproductive system

reproductive system

sexual and asexual reproduction

how do organisms interact with their environment on an organismal level?

muscular/nervous systems

muscular/nervous systems

complex movements