Common Requirements of living
things - ANIMALS – Chapter 5
Autotrophic Unicellular Organisms
Light energy
Water + dissolved
Inorganic nutrients
Carbon dioxide
+ Oxygen
Diffusion & osmosis in / out of the cell
- Active & Passive
Heat energy
Organic
compounds
Carbon dioxide
+ Oxygen
Wastes
Heterotrophic Unicellular Organisms
Organic matter
‘food’
Water + dissolved
Inorganic nutrients
Heat energy
Water +
dissolved
Inorganic
nutrients
Oxygen
Carbon dioxide
Diffusion & Osmosis in and out of the cell
- Active and passive
Phagocytosis or endocytosis of organic
matter
Organic wastes
No Digestion Required
• Very few multicellular animals
absorb nutrients directly from
the environment.
– Exceptions include parasites that
absorb nutrients that have been
digested by the host.
– In such cases there is no need for
digestion
– Examples :
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Blood parasites
Protozoan parasites
Tapeworms
Acanthocephalans
Corals
Most reef-building corals have a
symbiotic relationship with
photosynthetic algae, called
zooxanthellae. which live in their
gastrodermis tissue.
The zooxanthellae convert sunlight,
carbon dioxide, and water into
oxygen and carbohydrates that feed
the coral polyps and help them
produce reef-building calcium
carbonate.
In return, the corals provide the
zooxanthellae with protection and
the compounds they need for
photosynthesis.
Pigments in zooxanthellae also give
corals their beautiful orange, red,
purple, and yellow colors.
Movement of substances into & out of
unicellular organisms
Passive diffusion in and out
Bulk Transport requiring
energy
Intracellular Digestion
• In intracellular digestion, food particles are engulfed by
endocytosis and digested within food vacuoles.
– Protozoa, sponges.
Cell Specialisation in Simple Multicellular
Organisms
Sponge feeding
Cell Specialisation in Simple Multicellular
Organisms
Sponge feeding
Extracellular Digestion
• Extracellular digestion is the breakdown of food
particles outside cells.
– Digestion occurs in the alimentary canal.
– Cells lining the lumen of the alimentary canal are
specialized for secreting enzymes or absorbing nutrients.
Intracellular v Extracellular Digestion
Cell Specialisation in Simple
Multicellular Organisms
Cell Specialisation in Simple
Multicellular Organisms
Cnidarians feeding
Feeding Mechanisms – Particulate Matter
• The upper portion of lakes and oceans
contains very small animals and plants
(plankton) that drift with the water
currents.
• Along with plankton, there is also organic
debris floating in the water column and
mixed in with the sediment.
• Many organisms feed on this particulate
matter.
Feeding Mechanisms – Particulate Matter
• Suspension feeders use ciliated
surfaces to create a current
that draws drifting food
particles into their mouths.
– Many use mucous sheets to
entrap food.
• Tube dwelling polychaetes,
• bivalve molluscs,
hemichordates,
protochordates.
Feeding Mechanisms – Particulate Matter
– Others use
sweeping
movements of
setae-fringed legs
to create currents.
• Fairy shrimp,
daphnia, barnacles.
Feeding Mechanisms – Particulate Matter
• Filter feeding is a form
of suspension feeding
that involves straining
food from the water as
it passes through a
filtering device.
– Herring, menhaden,
basking sharks,
flamingos, baleen
whales.
Feeding Mechanisms – Particulate Matter
• Deposit feeders consume the
organic matter (detritus) that
accumulates on the
substratum.
– Many annelids simply eat the
substrate, digesting organic
matter.
– Others use appendages to
gather organic deposits and
move them to the mouth.
• Scaphopods, sedentary or
tube-dwelling polychaetes,
some bivalves, some
annelids.
Feeding Mechanisms
• Predators have evolved a variety of
ways to capture, hold, and swallow
prey.
– Many swallow food items whole.
– Some have specialized teeth,
beaks, or tooth-like structures.
– Some have highly elastic jaws and
distensible stomachs to
accommodate large meals.
Cell Specialisation in Vertebrate
Multicellular Organisms
Cell Specialisation in Vertebrate
Multicellular Organisms
The different
systems!
Animal’s bodies are
composed of different
systems, each system has
it’s own functions.
All together these systems
work together to enable
the animal to survive.
http://video.nationalgeographic.com/vid
eo/player/science/health-humanbody-sci/human-body/human-bodysci.html
Obtaining nutrients and energy
• Animals are heterotrophs must consume food in order to
obtain nutrients and energy.
• Animals are adapted to obtain food in a variety of ways
python vs croc
Why We Eat
• Regardless of what an animal eats, an
adequate diet must satisfy three nutritional
needs:
– Fuel/ Energy for all cellular work.
– Nutrients:
• The organic raw materials for biosynthesis.
• Essential nutrients, substances such as vitamins that
the animal cannot make for itself.
Required Nutrients
• Carbohydrates - source of immediate energy for all living
organisms. The monosaccharide glucose is broken down to make
ATP in cellular respiration.
• Lipids- Fats and oils required for cell membranes, hormones and
vitamins.
• Amino Acids - The building blocks of proteins. The body can
make some amino acids but others it can’t make these are the 9
essential amino acids. Need to be regularly eaten.
• Vitamins - Organic compounds needed for cellular processes,
e.g. making enzymes.
• Minerals - needed for structural components and for enzyme
molecules.
The Digestive System
• Ingestion- intake of food into the body
• Digestion- physical and chemical breaking down of food
• Absorption- nutrient molecules move into the circulatory
system and ultimately into the cells.
• Egestion/ Elimination- removal of waste from the body
Two Types of Digestion.
Physical digestion.
– Food physically broken it down into smaller pieces in order
to increase surface area and enable maximum efficiency of
chemical digestion.
Teeth
Mammalian teeth are
specialized for different
functions.
Incisors – biting, cutting,
stripping leaves.
Canines – seizing, piercing,
tearing.
Premolars & molars –
grinding and crushing.
Teeth
Mammalian teeth are
specialized for different
functions.
Incisors – biting, cutting,
stripping leaves.
Canines – seizing, piercing,
tearing.
Premolars & molars –
grinding and crushing.
Feeding Mechanisms
• Herbivorous animals have
evolved special devices for
crushing and cutting plant
material.
– Snails have a radula for scraping
algae or plant material.
– Insects have grinding & cutting
mandibles.
Feeding Mechanisms
• Herbivorous animals have evolved special devices
for crushing and cutting plant material.
– Mammals have wide corrugated molars for grinding.
Feeding Mechanisms
• Fluid feeders may bite and rasp at host tissues, suck
blood, and feed on contents of a host’s intestines.
– Many have specialized tubelike mouthparts.
Chemical Digestion
Breakdown of macromolecules
by enzymes- made in the gut,
salivary glands and pancreas into
molecules small enough to be
absorbed through the
alimentary lining.
Amylases- Break down
starches into simple sugars
Proteases- Break down
protein-into amino acids
Lipases- Break down lipids into
glycerol & Fatty acids
Introduction to the Human Alimentary System animation
Human digestion overview
View animation
then have a go
at the quizzes
and labelling
exercises
Digestion
• Stomach - majority of digestion occurs
– Mechanical digestion occurs as the muscles crush and move the food.
– Chemical digestion also occurs in the stomach, with the secretion of
gastric juices with have enzymes that break down the food.
• Small intestine -further digestion occurs but only on proteins and
carbohydrates to break them down into their amino acid building blocks.
Digestion-video.htm
Absorption
Most occurs in the small intestine.
Food at it’s smallest is then absorbed by the
cells of the intestine and passed along to the
blood stream.
Other mammals
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Different diets require different digestive systems.
Breaking down cellulose requires the enzyme cellulase.
Mammals can’t make this enzyme.
Cows have a 4 chambered stomach.
They chew and then regurgitate their food and chew it again before sending it
to the rumen where heaps of cellulose digesting bacteria live and allow the
breakdown of the cellulose to occurs.
Carnivore v
Herbivore
Caecum: a pouch extension
at the junction of the small
& large colon which in
herbivores contains
cellulose digesting bacteria.
Herbivorus mammals with
higher fibre diets may have
larger caecums to maximise
the opportunity for
cellulose digestion by
bacteria.
Digestion in birds
Most (not all) birds have :
• a crop for temporary storage
• a glandular part the proventriculus which
secretes mucus , HCl & enzymes
• a muscular gizzard which may contain grit or
small stones which grinds and mixes the food
and enzymes etc.