Download What is an Animal? Animals: General Characteristics 1. by far, the

What is an Animal?
Animals: General Characteristics
1. by far, the largest and most diverse
kingdom
2. eukaryote cells
eucaryotic
heterotrophs  no chloroplasts
lack cell walls around cells
aerobic require free oxygen for respiration
lots more mitochondria  lots more energy
more mitochondria than cells of any other
kingdom
need much more energy, much more active
3. ALL are multicellular
 best development of multicellularity of all kingdoms
4. most are motile and more active than
members of any other kingdom
Animal Records: Locomotion
Swimming
fastest pinniped 25mph (40kph)
Running
fastest land mammal
Cheetah, Acinonyx jubatus 60mph (96kph) in spurts
speeds up to 90 mph have been claimed, not verified
slowest land mammal
3 toed sloth, Bradypus tridactylus  6-8 ft/min (0.088mph)
Flying
Fastest Insect:
Dragonflies, some flies & moths 25-30 mph
black cutworm moth 70mph (rides cold fronts)
Fastest horizontal flight(bird):
racing pigeons and dunlin sandpipers 110mph
spine tailed swift, Chaetura caudacuta, 106mph
(170kph)
red breasted merganser ducks 100 mph
Fastest wingbeat of bird
hummingbird90b/sec
Fastest flight (mammal):
48mph  mexican free tailed bat
(others suspected to be faster)
Fastest diving flight: peregrin falcon 82mph (unverified to over
200mph); (but horizontal flight 30-60mph)
5. most animals store extra energy as
fats or oils
6. most with true tissues
epithelial
*muscular
*nervous
connective




covers body
used for movement
coordination and control
storage, transport, protection, etc
7. most with organs and complex organ
systems
plants have simple organs
animals have organs grouped into complex interacting
systems
most animals have a head with distinct sense
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organs and some kind of brain
most have some kinds of appendages for
collecting food or for movement
8. most reproduce both sexually and asexually
sexual reproduction always involves a sperm and
an egg
9. most show complex development, with
extended embryonic phase, often with
free living larval stages
10. most rely on simple or complex behaviors for
survival
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Animal Cells
animal cells are simpler in structure than plant
cells
no cell wall, no chloroplasts
many mitochondria
 animals have a much higher metabolism
than organisms in any other kingdom
Animal Tissues
The greater specialization of cells and tissues
increases the efficiency by which animals can carry
out life’s basic processes and allows for almost
limitless opportunities for evolutionary variations
and adaptations to numerous kinds of habitats and
environmental conditions.
The basis of this diversity is the kinds of tissues found
in the animal kingdom.
The fertilized egg, or zygote, typically progresses
through an embryonic stage in which three embryonic tissue
layers are established;
ectoderm
mesoderm
endoderm
These three embryonic tissue layers later differentiate
into the four basic tissue types of the adult and all the
resulting organs and organ systems.
The basic adult animal tissues are:
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1. epithelial tissues –
this is the most primitive,
presumably the first true animal
tissue to evolve.
It forms the outer coverings of animals
lines the inner and outer surfaces of all
body organs.
consists of cells fitted tightly together
forms layers that
create boundaries (squamous)
secretory glands (cuboidal,
columnar)
commonly ciliated
often glandular
2. connective tissues
are a very diverse group
includes tissues used for
support like bone and cartilage
storage like adipose tissue,
glue like areolar tissue,
transport nutrients, oxygen, wastes
and hormones throughout the
body like blood.
widely spaced cells
secrete matrix and fibers
Animals – Introduction (general); Ziser, 2006
(mainly collagen)
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ability to make collagen is unique to
animal kingdom
these extracellular elements used for:
mechanical stability
storage
protection
fibers composed of:
collagen (esp. skin, tendons, ligaments,
cartilage)
elastin
reticular fibers
3. muscle tissues
used for movement,
both voluntary movements such as
swimming or running,
and internal movements of various organs
such as the pumping heart, and peristalsis
of the digestive organs.
elongated fibers
highly contractile
usually with nervous innervation
4. nervous tissues
used to conduct information throughout the
body
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to sense internal and external environmental
changes,
and or coordination and control of muscles
and glands.
typically large cell body with one or more long
fibers extending from it
5. Reproductive tissues
The adult tissues are further differentiated into various subtypes.
Most adults retain some kinds of “embryonic cells”,
called stem cells, that can later differentiate into
replacement cells and tissues.
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Animal Organs & Organ Systems
animal anatomy & physiology is dominated by its
organs and organ systems
looking at detailed structure of animals we see a:
unity of design and function
Most animals have cells that have differentiated into
highly complex tissues and organs.
[Whereas the most complex plants had tissue systems and relatively
simple vegetative and reproductive organs, animals have complex
tissues forming complex organs and elaborate organ systems].
all animals live on earth
 subjected to same general conditions
these conditions have molded animal species
along similar patterns:
all must eat, breath, reproduce,
eliminate wastes, etc
much of the variations and diversity of animals is due
to their adaptations to a variety of habitats.
Each habitat dictates some general features in animal
anatomy and physiology:
differences arise as animals adapt to their specific
habitats
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result of natural selection
body size and shape affects interactions with the
environment
greater size creates problems with surface/volume
ratio
addressed by folding: eg resp digestive
systems or circulatory system
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the major organ systems found in one form or
another in most animals:
1. skin (integumentary system)
outer covering of animal
(plants also have outer covering but is much simpler in
structure and function)
simple to complex; no specific organs
can be used for a variety of uses: protection, support,
respiration, behaviors (signaling)
2. support (skeletal system)
especially terrestrial animals
(in land plants support was also an important
consideration; xylem-sclerenchyma, wood)
simple to complex;
organs are individual bones in vertebrates
different kinds: hydrostatic skeleton; exoskeleton,
endoskeleton
difference between aquatic and terrestrial animals
3. muscular system
unique to animals
 animals are much more active than any other
kingdom
any kind of body movements
simple to complex; individual muscles in arthropods and
vertebrates
external movements:
sessile vs motile
crawling, running, flying, swimming, burrowing, etc
4. digestive system
like fungi, and many protists and bacteria, animals are
heterotrophs  take in organic food
the food is much more complex
generally digest the food after it is eaten, not before as in
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fungi or some plants
mouth, throat, stomach, intestines, liver, digestive glands,
pancreas, rectum
lots of specialization depending on
how an animal gets its food & what kind of food:
eg. predator, herbivore, parasite, filter feeder
5. respiratory system
like plants, all animals require O2 to produce energy
since animals are more active than plants they require more
efficient ways to get oxygen
(plants just used simple pores:
stomata or lenticels, or pneumatophores)
air: throat, tracheae, larynx, bronchi and bronchioles,
lungs, diaphragm
water: gills, skin, airsacs,
often this system is closely associated with some kind of
circulatory system to more effectively collect and
distribute the oxygen
6. excretory system
having greater metabolism, animals generate more wastes
 need more effective way to get rid of wastes
(fungi, protists, bacteria  diffusion; plants 
stomata, converted to “secondary plant products”
for defense or support or stored in woody tissue)
if larger often associated with circulatory system, to collect
and export wastes
also, often associated with methods of salt and water
balance
7. circulatory system
in small organisms gas exchange and food and wastes enter
and leave by simple diffusion
in large, multicellular organisms need some way to move
things around from place to place, organ to organ
large animals have circulatory system
(plants had vascular tissue system)
small animals don’t need this
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8. endocrine system
animals still use hormones for things that have slow
response time:
growth, development, reproductive cycles,
9. nervous system
unique to animals
all life uses chemicals to help coordinate and control
activities
eg. plant hormones, but also fungi, bacteria, protists
animals move much more quickly, must respond to things
much quicker
 chemicals may take minutes or hours to
produce a response
but use nervous system for quick reactions:
movements, emergencies, etc
10. senses
to get quick responses need sense organs to monitor the
environment
11. immune system
most multicellular forms have ways to protect themselves
against pathogens and disease
(plants: sap protects damaged areas and
prevents invasion; also produce many compounds
that discourage herbivores and parasites)
animals are much more active and much more likely to
encounter pathogens and parasites
 some have developed rather elaborate ways to
protect themselves
12. reproductive
most animals reproduce both asexually and sexually
 higher animals reproduce only sexually
some go through alternation of generations
animals typically go through more complex stages of
development, sometimes spending years in immature
forms
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Animal Reproduction
Most animals reproduce both sexually and
asexually.
Asexual reproduction produces genetically identical
copies (ie. clones)
sexual reproduction produces genetically unique
offspring.
Many organisms reproduce asexually at one time of
the year or under a certain set of conditions and
sexually at other times of the year or under a
different set of conditions
thus producing a complex life cycle where
asexual and sexual types of reproduction
alternate.
Within this life cycle, some organisms have a
completely different appearance depending on
whether they are the sexually or asexually
reproducing forms
= alternation of generations
Even in animals which rely mainly on sexual
reproduction for procreation (such as Vertebrates)
asexual reproduction appears in the form of
wound healing,
tissue repair and replacement
budding
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regeneration.
Some Kinds of asexual reproduction in animals:
1. Budding:
In some animals a new offspring
begins as an outgrowth of the parent and may either
remain attached to form a colony of interconnected
individuals such as in coral
or a long chain of reproductive units such as the
proglottids of a tapeworm.
In other animals the bud may eventually break
away to begin an independent life such as occurs in
hydra.
Sponges (Animal Kingdom) form a type of
internal bud, called a gemmule. The parent sponge
forms several gemmules before it dies in the fall. The
gemmules overwinter and then grow into new sponges
in the spring.
2. Regeneration
It is best seen simple animals such as the
planaria, insects and starfish
In some animals, such as lizards, when a body
part is broken off accidentally or by a predator the
animal is able to regrow the missing part.
Some animals have great powers of
regeneration while others can only
regenerate certain cells or tissues.
3. Fragmentation:
Some animals spontaneously break into many
separate pieces which then regrow into a complete
animal.
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Sponges and starfish can be mechanically
broken apart and each piece will grow into a complete
animal
4. Polyembryony (twinning):
the embryo or larva itself splits into separate
individuals.
In humans this process occurs to produce
identical twins.
Most parasitic flatworms are able to produce
numerous larvae from a single fertilized egg.
Some kinds of sexual reproduction in animals
[In most animals meiosis is restricted to the formation of haploid
gametes]
[most animals are diploid organisms]
In most cases, sexual reproduction involves the
union of male and female gametes.
Most variations in sexual reproduction depend on
the actual form of the male and female
gametes,
how the gametes are produced or
whether the developing egg has actually
been fertilized or not before it begins development.
1. Isogamy
When both sex cells are identical
2. Heterogamy & Oogamy:
When the sex cells are dissimilar
The gametes are produced by the process of
meiosis which differs from mitosis in
that only one of each chromosome ends up in the cells
after division.
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The male gamete, the sperm, is small and
almost always flagellated.
The female gamete, the egg, us usually large
since it contains yolk, and spherical.
3. Monoecious Organisms or Hermaphrodites:
are organisms containing both male and female
reproductive organs
Many animals, especially those that are
sessile (nonmotile) or parasitic, are
hermaphroditic.
4. Dioecious Organisms:
Are organisms that produce either male or
female reproductive organs and games but not
both at the same time.
many animals are dioecious
5. Protandry:
is the ability in some animals to switch
their sex based on environmental cues.
6. Sexual Dimorphism:
in many dioecious animals the males and
females are not identical, but differ in appearance.
in most invertebrates, the male is usually
smaller than the female
in vertebrates the female is usually the
smaller one.
In birds the male is usually more brightly
colored.
7. Parthenogenesis :
In these cases the unfertilized egg is able
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to develop even though it has not been fertilized
by a sperm.
Most rotifers, and some social insects such
as bees and ants reproduce this way.
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Animal Development
following sexual reproduction, animals often go
through a series of complex developmental stages
Members of the animal kingdom have the most
complex developmental cycle of any living
organism.
Animal development can be subdivided into several
sequential processes:
gametogenesis,
fertilization and
embryological development
larval period
Embryological development includes the processes of
cellular and tissue changes:
growth
 increase in the # of cells
determination  fate of cell is sealed
differentiation  specialization of cells
morphogenesis  origin of adult form
organogenesis  origin of adult organs
Embryological development typically progresses
through several distinct stages (phases) of
development:
zygote:
cleavage
morula
blastula (blastocyst)
gastrula
neurula
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After fertilization, the zygote typically goes through
various developmental (or immature) stages as
the life cycle progresses from the zygote to
adult.
Such terms as larva, pupa, metamorphosis,
nymph, fetus, etc are used to describe these
immature stages.
some processes of animal development:
1. Gametes.
The gametes are produced by the process of
meiosis which differs from mitosis in that
only one of each chromosome ends up in
the cells after division.
The male gamete, the sperm, is small and
almost always flagellated.
The female gamete us usually large since it
contains yolk, and spherical.
2. Fertilization.
At fertilization only a single sperm penetrates
and adds its chromosomes to those in the
egg.
The fertilized egg then has a pair of each
chromosomes, one from the male parent
and the other from the female parent.
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To prevent additional sperm from penetrating
the egg a fertilization cone is produced
to move the original sperm into the egg
quickly.
Then a fertilization membrane expands
around the egg and pushes away and
“locks out” other sperm cells.
3. Embryonic Development
a. Cleavage.
The first identifiable period of embryonic
development occurs as the fertilized
egg begins to divide.
These early divisions are called cleavage
divisions and each cell produced is a
blastomere.
b. Morula:
continued division leads to a solid ball of
cells called the morula.
c. Blastula or Blastocyst:
If the embryo is spherical it is called a
blastula; if it is a flattened disc it is
called a blastocyst,
both are equivalent stages.
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At the blastula stage, the cells form a hollow
sphere.
The cavity inside is called the blastocoel.
4. Embryonic Development –
early development requires some form of
nourishment
eg. plants  endosperm
eg. animals  yolk
d. Gastrula or Primitive Streak:
In the gastrula, a depression forms at one
end of the embryo,
cells move in to form a saclike pouch.
The embryo is now essentially two
layered.
The cavity of this new pouch is called the
archenteron which is surrounded by
the original, now much smaller
blastocoel.
The archenteron opens to the outside
through the blastopore.
The blastopore will eventually become
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either the mouth or the anus of the
adult animal.
In the case of the blastocyst, the flattened
embryo, this next stage is called the
primitive streak stage.
A slit forms in the center of the sheet of
cells (= the primitive streak) and cells
migrate into the slit and under the
original layer of cells to form a double
layered disc.
This stage is equivalent to the gastrula
above.
4. Larvae.
Further development varies considerably in
different animal groups.
In some animals, especially marine animals,
the embryo soon becomes a freeliving
larva.
While each phylum and sometimes each class
usually has its own characteristic larvae
there are a few larval forms that are found in
more than one phylum.
Similar larvae imply similar ancestry;
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indicating that the phyla are relatively
closely related.
The larvae listed below are evolutionarily
significant.
A. Planula.
A simple multicellular, oval larva with no discernable
organs its surface is covered with cilia
B. Trochophore.
A top-shaped larva with a digestive tract beginning at
the mouth and terminating in an anus.
Tufts of cilia are found at each end and bands of cilia
surround the wider central area of the larva
C. Nauplius.
A triangular larva with three pairs of jointed
appendages, eyespots, and
digestive organs.
D. Bipinnaria.
An elongated larva that bulges at both ends, with a
curving digestive tract
with mouth and anus, and bands of cilia encircling the
larva
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Animal Behavior
behavior is an important tool for animal survival
social, mating, territorial behaviors etc
all behavior has a genetic basis
 follows Darwinian evolution to some degree
predictable
programmed
adaptive (reproductive advantage)
simple behaviors are either:
Instinctive
or
taxes
reflexes
fixed action patterns
mimicry, camoflage
Learned
imprinting
habituation
conditioning
social:
courtship
reproductive
family
group
The most basic theory of behavior:
stimulus 
response
may or not be aware of the stimulus
stimulus may be internal or external
 perceived by sensory organ or cell
response is controlled or modified by nervous or
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endocrine system
The simplest behaviors are movements of some kind
Tropisms  involve response to a single stimulus
by a stationary organism
inherited, rigid behavior
cannot be controlled or modified
Taxes 
response to single stimulus by motile
organism
Reflexes simple unlearned, unmodifiable
response in organisms with well
developed nervous systems including
CNS & PNS
involves a complete functional circuit of
nervous system:
from receptor to effector
eg. blinking as a reflex arc
eg. touching hot skillet
but what is learned vs. innate
eg. Newborns don’t blink when object is brought close to their
eyes
 learned
 maturation of pathways for reflex
eg. right or left thumb on top when folding hands
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behaviors in invertebrates are usually highly rigid,
stereotyped, patterns
almost all are genetically preprogrammed
in more complex animals (vertebrates) learning plays
a larger role
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