Download Ch 27 Animal Systems I

1.
2.
3.
4.
Review What types of food do herbivores eat,
What are nutritional symbionts
Relate Cause and Effect How might a corral be
affected if all its symbiotic algae died
Review what are two types of digestion animals
use to break down and absorb food
Compare and Contrast What is a major structural
difference between gastrovascular cavities and
digestive tracts
CH 27 ANIMAL SYSTEMS I
27.1 Feeding and Digestion

What and how you eat depends on how you look
and act.
Filter Feeders

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Catch algae and small animals by using modified
gills or other structures as nets that filter food
items out of water
Barnacles to blue whales.
Detritivores

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Feed on detritus, often obtaining extra nutrients
from the bacteria, algae, and other
microorganisms that grow on and around it
Earthworms to cleaner shrimp.
Carnivores


Eat other animals
Wolves or orcas
 Use
teeth, claws, and speed or stealthy hunting tactics
to bring down prey

Carnivorous invertebrates
 Cnidarians
paralyze prey with poison-tipped darts
 Spiders immobilize their victims with venomous fangs.
Herbivores


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Eat plants or parts of plants
Locusts to cattle
May specialize in eating seeds or fruits.
Symbionts

Organisms involved in a symbiosis.
Parasitic Symbionts


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Parasites live within or on a host organism
Feed on tissues or on blood and other body fluids
Can cause serious diseases.
Mutualistic Symbionts

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Reef-building corals depend on symbiotic algae
that live within their tissues for most of their
energy
Algae gain nutrition from the corals’ wastes and
protection from algae eaters.
Intracellular Digestion

Digest food inside
specialized cells that pass
nutrients to other cells by
diffusion.
Extracellular Digestion


Process in which food is broken down outside cells
in a digestive system and is then absorbed
Most common in more complex animals.
Gastrovascular Cavities

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Interior body space whose
tissues carry out digestive
and circulatory functions
Single opening through
which they both ingest food
and expel wastes.



Cells lining the gastrovascular
cavity secrete enzymes and
absorb digested food
Other cells surround food
particles and digest them in
vacuoles
Nutrients then transported
throughout body.
Digestive Tracts


Digest food in a tube which has
two openings
Food moves in one direction
 Entering
the body through the
mouth
 Wastes leave through the anus

Many invertebrates and all
vertebrates.
Digestive Tracts



Specialized structures
perform different tasks as
food passes through them
Mouth secretes digestive
enzymes that start the
chemical digestion of food
Specialized mouthparts or a
muscular organ called a
gizzard breaks food into small
pieces.
Digestive Tracts



Chemical digestion begins or
continues in a stomach that
secretes digestive enzymes
Chemical breakdown continues
in the intestines, sometimes
aided by secretions from other
organs
Intestines also absorb the
nutrients released by digestion.
Solid Waste Disposal


Some indigestible material will
always be left
Solid wastes, or feces, are
expelled through the single
digestive opening, or anus.
Eating Meat

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Have sharp teeth that grab, tear, and slice food like
knives and scissors would
Jaw bones and muscles are adapted for up-anddown movements that chop meat into small pieces.
Eating Plant Leaves


Need to tear plant cell walls and expose their
contents
Mouthparts that grind and pulverize leaf tissues.

Carnivors typically have short digestive tracts that
produce fast-acting, meat-digesting enzymes.


No animal produces digestive enzymes that can
break down the cellulose in plant tissue
Cattle have a pouchlike extension of their stomach
called a rumen, in which symbiotic bacteria digest
cellulose.
Pieces of boiled egg white are placed in a test
tube with hydrochloric acid, water, and pepsin
(enzyme that digests protein)
1. Describe the trend in the amount of protein
digested over time
2. About how many hours did it take for half
the protein to be
digested
3. How would you
expect the rate of meat
digestion to differ in an
animal that had less
pepsin

CH 27 ANIMAL SYSTEMS I
27.2 Respiration
Gas Diffusion and Membranes


Gases diffuse most efficiently across a thin, moist
membrane that is permeable to those gases
Larger the surface area membrane, the more
diffusion that can occur.
Requirements for Respiration


Large surface area of moist, selectively permeable
membrane
Difference in relative concentrations of oxygen and
carbon dioxide on either side of the respiratory
membrane.
Respiratory Surfaces of Aquatic Animals

Some aquatic invertebrates and a few chordates
rely on diffusion of oxygen and carbon dioxide
through their outer body covering.
Respiratory Surfaces of Aquatic Animals


Many aquatic invertebrates and most aquatic
chordates exchange gases through gills
Gills
 Feathery
structures that expose a large surface area of
thin, selectively permeable membrane to water

Capillaries
 Network
of tiny, thin-walled blood vessels.
Respiratory Surfaces of Aquatic Animals
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May actively pump water over their gills as blood
flows through inside
Gas exchange occurs as water passes over the gills.
Respiratory Surfaces of Aquatic Animals
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Lungs
 Organs
that exchange oxygen and carbon dioxide
between blood and air

Aquatic reptiles and aquatic mammals, must hold
their breath underwater.
Respiratory Surfaces in Land Invertebrates

Wide variety of respiratory structures
 Respire
across their skin
 Mantle cavity
 Book lungs
 Tracheal tubes.
Book Lungs

Which are made of parallel, sheetlike layers of thin
tissues containing blood vessels.
Tracheal Tubes
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Air enters and leaves the system through openings
in the body surface called spiracles
Most invertebrates.
Lung Structure in Vertebrates
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Lung structure in terrestrial vertebrates varies
Processes of inhaling and exhaling are similar
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Inhaling brings oxygen-rich air through the trachea
(airway) into the lungs
Oxygen diffuses into the blood through lung
capillaries
Carbon dioxide diffuses out of capillaries into the
lungs
Oxygen-poor air is then exhaled.
Amphibian, Reptilian, and Mammalian
Lungs

Typical amphibian lung is little more than a sac with
ridges.
Amphibian, Reptilian, and Mammalian
Lungs

Reptilian lungs are divided into chambers
 Increase
the surface area for gas exchange.
Amphibian, Reptilian, and Mammalian
Lungs

Mammalian lungs branch extensively
 Filled
with Alveoli.

Alveoli
 Provide
enormous surface area for gas exchange
 Enable mammals to take in the large amounts of
oxygen required by their high metabolic rates.
Bird Lungs
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
Air flows mostly in only one direction, so no stale
air gets trapped in the system
Gas exchange surfaces are continuously in contact
with fresh air
 Highly
efficient
 Enables flight, at high altitude for extended time.
CH 27 ANIMAL SYSTEMS I
27.3 Circulation

Heart
 Hollow,
muscular organ that pumps blood around the
body
 May have one or more
 May be part of either an open or a closed circulatory
system.
Open Circulatory Systems
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Blood is only partially contained within a system of
blood vessels
Arthropods and most mollusks have open
circulatory systems.

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One or more hearts or heartlike organs pump blood
through vessels
Empty into a system of sinuses (spongy cavities)
where blood comes into direct contact with body
tissues.

Blood then collects in another set of sinuses and
makes its way back to the heart.
Closed Circulatory Systems
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Blood circulates entirely within blood vessels that
extend throughout the body
Many larger, more active invertebrates, including
annelids and some mollusks, and all vertebrates
have closed circulatory systems.
Closed Circulatory Systems

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Heart or heartlike organ forces blood through
vessels
Nutrients and oxygen reach body tissues by
diffusing across thin walls of capillaries
Pumped at higher pressure and circulates more
efficiently.
Single-Loop Circulation


Single pump that forces blood
around the body in one direction
Most vertebrates with gills.
Single-Loop Circulation
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Atrium
 Receives

blood from the body
Ventricle
 Pumps
blood out of the heart and to
the gills
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Oxygen-rich blood travels from the
gills to the rest of the body
Oxygen-poor blood then returns to
the atrium.
Double-Loop Circulation
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Two-pump circulatory system
Most vertebrates that use
lungs
First loop is powered by one
side of the heart
Forces oxygen-poor blood
from the heart to the lungs.
Double-Loop Circulation
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Blood picks up oxygen and
drops off carbon dioxide in the
lungs
Returns to the heart
Other side of the heart pumps
oxygen-rich blood through the
second circulatory loop to the
rest of the body.

Amphibian hearts usually have three chambers:
two atria and one ventricle
 Left
atrium receives oxygen-rich blood from the lungs
 Right atrium receives oxygen-poor blood from the
body
 Both atria empty into the ventricle.

Reptilian hearts typically have three chambers: two
atria and one ventricle
 Have
a partial partition in their ventricle
 Less mixing of oxygen-rich and oxygen-poor blood
than in amphibians.


Four-chambered hearts are
actually two separate pumps
working next to one another
Partitions evolved that
divided the original two
chambers into four,
transforming one pump into
two parallel pumps.
CH 27 ANIMAL SYSTEMS I
27.4 Excretion
The Ammonia Problem
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Breakdown of proteins by cells releases a nitrogencontaining waste: ammonia
Ammonia is poisonous
Moderate concentrations of ammonia can kill most
cells.
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Excretion
 Elimination
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of metabolic wastes, such as ammonia
Small animals in wet environments get rid of
ammonia by allowing it to diffuse out of their body
fluids across their skin
Most larger animals have excretory systems that
process ammonia and eliminate it from the body.

Animals that cannot dispose of ammonia
continuously have evolved ways to store
nitrogenous wastes until they can be eliminated.
Storing Nitrogenous Wastes

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Ammonia itself cannot be stored in body fluids
because it is too toxic
Insects, reptiles, and birds convert ammonia into a
sticky white compound called uric acid
 Much
water.
less toxic than ammonia and is less soluble in

Mammals and some amphibians convert ammonia
to urea
 Urea
is less toxic than ammonia
 Is highly soluble in water.
Maintaining Water Balance

Excretory systems are extremely important in
maintaining the proper balance of water in blood
and body tissues
 May
also excrete excess water or have to conserve
water.
Kidneys

Separate wastes and excess water from blood to
form urine
 Pump
ions from salt to create osmotic gradients
 Water then “follows” those ions passively by osmosis
 Usually cannot excrete excess salt.
Freshwater Animals

Freshwater invertebrates lose ammonia to their
environment by simple diffusion across their skin.

Freshwater fishes and amphibians eliminate
ammonia by diffusion across the same gill
membranes they use for respiration.

Bodies of freshwater
animals, such as fishes,
contain a higher
concentration of salt
than the water they live
in.

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Water moves into their
bodies by osmosis
Salt diffuses out.
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Freshwater fish excrete
lots of watery urine
Don't drink water
Actively pump salt in
across their gills.
Saltwater Animals

Typically release ammonia by diffusion across their
body surfaces or gill membranes.

Many marine invertebrates have body fluids with
water concentrations similar to that of the
seawater around them.

Many saltwater animals,
such as fishes, contain a
lower concentration of
salt than the water they
live in.

Lose water through
osmosis, and salt
diffuses in.
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Saltwater fish conserve
water by producing very
little concentrated urine
Drink water
Actively pump salt out
across their gills.
Excretion in Terrestrial Animals
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Land animals can lose large amounts of water from
respiratory membranes that must be kept moist
Must eliminate nitrogenous wastes in ways that
require disposing of water.
Terrestrial Invertebrates

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Produce urine in nephridia
Nephridia
 Tubelike excretory
structures that filter body fluid.
Terrestrial Invertebrates

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Body fluid enters the nephridia through
nephrostomes and becomes more concentrated as
it moves along the tubes
Urine leaves the body through excretory pores.
Terrestrial Invertebrates


Insects and arachnids convert
ammonia into uric acid
Malpighian tubules
 Absorb
uric acid from body
fluids
 Concentrate the wastes and
add them to digestive wastes.



Water is absorbed from
wastes
Crystals form a thick paste
which leaves the body
through the anus
Paste contains little water
 Minimizes
water loss.
Terrestrial Vertebrates


Mammals and land amphibians
convert ammonia into urea
Excreted in urine by the
kidneys.

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Reptiles and birds convert ammonia into uric acid
Passed through ducts into a cavity that also
receives digestive wastes from
the gut
Walls of cavity absorb water
 Uric
acid separates as thick, milky-white paste
recognized as “bird droppings.”



Most vertebrate kidneys cannot excrete
concentrated salt
Most vertebrates cannot survive by drinking
seawater
All that extra salt would overwhelm the kidneys,
and the animal would die of dehydration.
CH 28 ANIMAL SYSTEMS II
28.3 Reproduction
Asexual Reproduction

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Many invertebrates and a few chordates
Requires only one parent
Can reproduce rapidly
Lack genetic diversity.
Types of Asexual Reproduction

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Divide in two
Budding
Parthenogenesis
 Females
lay eggs that develop without being fertilized
by a male.
Sexual Reproduction





Involves meiosis, creates gametes
Male and female gamete join to create zygote
Genetic diversity
Requires two individuals of different sexes
Greater needs.

Most animal species that reproduce sexually have
individuals that are either male or female
 Some
species are hermaphrodites
 Some species switch sexes.
Reproductive Cycles

Some invertebrates have life cycles that alternate
between sexual and asexual reproduction.



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Blood flukes mature in the body of an infected
person
Reproduce sexually and release embryos that pass
out of the body in feces
Embryos develop into larvae and infect snails and
reproduce asexually
Larvae infect people.
Jellyfish

Aurelia polyps produce medusas asexually by
budding.

Medusas reproduce sexually by producing eggs and
sperm that are released into the water.

After fertilization, the resulting zygote grows into a
free-swimming larva.

Larva eventually attaches to a hard surface and
develops into a polyp continuing the cycle.
Internal Fertilization



Eggs are fertilized inside the body of the eggproducing individual
Many aquatic and all terrestrial animals
Sperm may taken in from surrounding water, be
gathered by the female, or deposited in side the
female.
External Fertilization


Eggs are fertilized outside the body of the eggproducing individual
Aquatic invertebrate and vertebrates.
Development and Growth



After fertilization, the zygote divides through
mitosis and differentiates
Development occurs under different circumstances
in different species
Care and protection given to developing embryos
also varies widely.

Animals may be oviparous, ovoviviparous, or
viviparous.
Oviparous


Embryos develop in eggs
outside the parents’ bodies
Most invertebrates, many
fishes and amphibians, most
reptiles, all birds, and a few
mammals.
Ovoviviparous



Embryos develop within the
mother’s body, but depend
entirely on the yolk sac of their
eggs
Young do not receive any
additional nutrients from the
mother
Guppies and some shark
species.
Viviparous


Embryos obtain nutrients
from the mother’s body
during development
Most mammals and some
insects, sharks, bony fishes,
amphibians, and reptiles.
Viviparous

Young are nourished by secretions produced in the
mother’s reproductive tract in insects, and in some
sharks and amphibians.
Viviparous

Placenta
 Specialized
organ that enables exchange of respiratory
gases, nutrients, and wastes between the mother and
her developing young

In placental mammals.

Most newborn mammals and newly hatched birds
and reptiles look a lot like miniature adults.


As invertebrates, nonvertebrate chordates, fishes,
and amphibians develop, they undergo
metamorphosis
Metamorphosis
 Developmental
process that leads to dramatic changes
in shape and form.
Aquatic Invertebrates



Have a larval stage that looks nothing like an adult
Swim or drift in open water before undergoing
metamorphosis and assuming their adult form
May have multiple larval stages.
Terrestrial Invertebrates


Some undergo gradual or
incomplete metamorphosis
Nymph
 Immature
forms that resemble
adults
 Lack functional sexual organs and
some adult structures

Molt several times and gradually
acquire adult structures.



Some undergo complete
metamorphosis
Larvae look nothing like their
parents, and they feed in
different ways
Pupa
 Stage
in which an insect larva
develops into an adult

Controlled by amount of juvenile
hormone produced.
Care of Offspring


Species that provide intensive or long-term
parental care give birth to fewer young than do
species that offer no parental care
Type and amount of care varies greatly.
The Amniotic Egg



Provides a protected
environment for an embryo to
develop out of water
One of most important
vertebrate adaptations to life
on land
Reptiles, birds, and a few
mammals.

Amnion
 Fluid-filled
sac that surrounds
and cushions the developing
embryo.

Chorion
 Regulates
the transport of
oxygen from the surface of
the egg to the embryo and
the transport of carbon
dioxide in the opposite
direction.

Yolk sac
 Contains
nutrient-rich food
supply for the embryo

Allantois
 Stores
waste produced by the
embryo
 Later fuses with the chorion.
Mammal Adaptations

The three groups of mammals:
 Monotremes
 Marsupials
 Placentals

All nourish their young with mother’s milk.
Monotremes


Lay soft-shelled, amniotic eggs that are incubated
outside her body
Young are nourished by milk produced by the
mother.
Marsupials


Bear live young that usually complete their
development in an external pouch
Young spend months attached to a nipple drinking
milk and growing inside.
Placentals


Nourished through a placenta before they are born
and by their mother’s milk after they are born
Born at a fairly advanced stage of development.