Download Introduction to Animals - Kent City School District

Introduction to
animals
Introduction to
Animals
Characteristics of Animals
• All multicellular
Eukaryotes
Heterotrophs (take in
food and internally digest
it)
• Store food reserves in
the liver as glycogen
Support Systems
• Have some type of skeletal support
• Endoskeleton inside and made of
cartilage &/or bone
• Exoskeletons found in arthropods
– Cover the outside of the body
– Limit size
– Must be molted making animal
vulnerable to predators
Cicada Molting Exoskeleton
Support Systems
• Worms and
echinoderms
(starfish) have
fluid-filled internal
cavities giving them
support
• Called hydrostatic
skeletons
Movement
• Animals such as sponges may be
sessile (attached & non-moving)
• Animals that move very little
are said to be sedentary (clam)
• Animals that can move are
motile
• Have muscular tissue to provide
energy for movement
SESSILE
Sponge
SEDENTARY
Chiton
MOTILE
Cheetah
Reproduction in Animals
• All animals are capable of
sexual reproduction
• Some animals like sponges and
earthworms are hermaphrodites
producing both eggs and sperm
• Hermaphrodites may exchange
sperm and NOT fertilize their
own eggs
Leeches Exchange Sperm
During Mating
leech
Mating
Reproduction in Animals
• Females of some animals
produce eggs, but the eggs
develop without being fertilized
• Called Parthenogenesis
• New offspring will be all female
Parthenogenesis occurs in some
fishes, several kinds of insects,
and a few species of frogs and
lizards
Parthenogenesis in the Komodo
Dragon
Female
Beetles
Mating
Courtship
Young
Male
Mating and
Mating
Behaviors
Levels of Organization
• Sponges are the ONLY animals that
have just the cellular level
• All other animals show these levels
– cell, tissue, organ, and system
• Cells may specialize (take own
different shapes and functions)
• Cells are held together by cell
junctions to form tissues
Atom
Molecule
or
compound
Levels of Organization
Organ
Tissue
Organ
system
Organelle
CELL
Life begins
Organism
Invertebrate groups
Characteristics of
Invertebrates
• Simplest animals
• Contain the greatest number of
different species
• Most are aquatic (found in water)
• Do NOT have a backbone
• Includes sponges, cnidarians,
flatworms, roundworms, annelids,
mollusks, arthropods, and
echinoderms
1. Phylum Porifera
(Sponges)
Sponge - Porifera
Osculum
of
Sponge
Phylum Porifera
(exit for water)
(Sponges)
(skeleton)
(digest and
distribute food)
Choanaocyte
*** Sponges are Parazoans: they contain NO true tissues
*** Sponges are filter feeders
2. Phylum Cnidaria
Jellyfish, Corals, and
other Stingers
General Characteristics
• Simple body plan-bag shaped organism
• Radially symmetrical organization
• Consists of a mouth and a sac-like cavity
• Lacks an anus
• The mouth is surrounded by a ring of
tentacles
• The cavity in the center of the gut,
called the gastrovascular cavity.
Two Body Forms
• Polyps
• Medusae
- attached to a
- free floating
surface
-ex: jellyfish
- ex: sea anemones
-mouth points
- mouth points up
down
Sea Anemone - Cnidaria
Tentacles of Sea Anemone
More Cnidarians
Brain Coral
Red jellyfish
3. Phylum Platyhelminthes
(Flatworms)
• Platyhelminthes consists of three kinds of
acoelomate flatworms.
• 1. Free-living Flatworms: such as planarians,
which are carnivorous scavengers.
• 2. Flukes: are internal, or external, parasites
that suck tissue fluids or blood.
• 3. Tapeworms: internal parasites that live in
the intestinal tracts of vertebrates.
Flatworms - Platyhelminthes
Marine Flatworm
Planarian
Planaria
Tapeworm
Scolex (head)
Young
Proglottids
Old
Proglottids
** tapeworms appear to be segmented, but they are not true
“segmented” worms
4. Phylum Nematoda
(Roundworms)
• Found in fresh water, marine, moist soil,
tissues of plants, and tissues and body fluids
of animals
• A complete digestive tract is present and
nutrients are transported through the body in
the pseudocoelomic fluid.
• Free-living forms are important in
decomposition
• Animal parasitic forms can be hazardous to
health.
(Trichinella spiralis in humans via
undercooked infected pork)
Nematode
Nematode
7. Phylum Annelid
(Segmented Worms: includes leeches,
earthworms and polychaetes)
Leeches are freshwater but some are
terrestrial in moist vegetation. Many are
carnivorous and feed on small
invertebrates, while some attach
temporarily to animals to feed on blood.
They have 2 suckers, one at each end.
leech
• Earthworms ingest soil, extract
nutrients in the digestive
system and deposit undigested
material (mixed with mucus
from the digestive tract) as
casts through the anus.
Important to farmers as they
till the soil and castings
improve soil texture
Polychaetae drift and swim in
the plankton, some crawl along
the sea floor, and many live in
tubes they construct by mixing
sand and shell bits with mucus.
Tube-dwellers include the
fanworms that feed by trapping
suspended food particles in
their feathery filters which are
extended from the tubes.
Phylum Annelid
Polychaete Worm
Fanworm
6. Phylum Mollusca
(snails, bivalves, octopuses and
squids)
• In Squids, the shell is
reduced and is
internal.
• In octopuses, the shell
is entirely absent.
• Octopuses have a
highly developed
nervous system with a
large, complex brain.
Snails
Mollusca (With and Without Shells)
snail
nautilus
scallop
nudibranch
octopus
8. Phylum Arthropoda
(spiders, insects, crustaceans, and various
related organisms)
• Arthropods have two kinds of life
cycles…(1) complete metamorphosis, (2)
incomplete metamorphosis.
• Arthropods have: * jointed appendages, *
a well-developed nervous system, *
specialized body segments, and * an
exoskeleton made of chiton.
The specialized body segments are the: Head, Thorax and Abdomen
Incomplete Metamorphosis
(immature forms are often called nymphs)
Nymphs resemble the adult in form except for being
smaller and lacking fully developed wings and sexual
organs.
Life Cycle: Egg
nymph
adult
Complete metamorphosis
Immature forms are called larvae (larva, singular).
The pupal stage is a transition stage, when the larva is
transformed to the adult.
Pupa molts to the adult form.
Life Cycle: Egg --> larva --> pupa --> adult
Arthropoda (insects, spiders,
crustaceans, horseshoe crab)
spider
crayfish
Horseshoe crab
Dung
beetle
9. Phylum
Echinodermata
(sea stars (starfish), sea urchins and
sand dollars)
Echinoderms are Coelomates
Deuterostomes
Echinoderms have complete
digestive systems
Although some adults exhibit
radial symmetry, some
Echinoderms
Sea fan (crinoid)
starfish
Brittle star
Sand dollar
Sea cucumber
Vertebrate
Groups
10. Phylum
Chordata
• The Phylum Chordata
consists of animals
that exhibit the
following four
features. In many
cases, these features
are temporary,
1. A Notochord
• A notochord
provides
support for
the body. It
is a flexible
cord located
on the
Notochord
2. A Dorsal Hollow
Nerve Cord
• A dorsal
hollow nerve
cord forms
the basis of
the nervous
system. In
some
3. Pharyngeal Gill
Slits
• Pharyngeal Gill Slits
provides channels across the
pharynx to the outside of
the body. In some
chordates, the slits become
gills for oxygen exchange,
or for filter feeding, while
in others, the slits
4. A Muscular
Tail
• A muscular tail extends
beyond the digestive
system. In many
chordates, such as
humans, the tail is lost
during embryonic
development.
There are Two Groups
of Chordates
• 1. Invertebrate Chordates:
includes lancelets and
tunicates.
• 2. Vertebrate Chordates:
includes
sharks, fish, amphibians,
reptiles,
Vertebrata
• More complex animals
• Most have a backbone made up
of individual bones called
vertebrae
• From simplest to most complex,
the phylum includes: fish,
amphibians, reptiles, birds, and
mammals
Vertebrate Backbone
Vertebrata
• Vertebrates have endoskeletons
(internal)
• Some vertebrates have
skeletons of cartilage (sharks,
rays, and skates)
• Other vertebrates have
skeletons of bone and cartilage
(reptiles, birds, & mammals)
Bone & Cartilage in Fetus
Fish
lancelet
ray
damselfish
anglerfish
Amphibia
salamander
toad
frog
newt
Reptilia
Turtle
Snake
Lizard
Alligator
Birds - Aves
hummingbird
ostrich
lovebirds
Mammalia
Body
Areas
Surfaces
•
•
•
•
Dorsal – back or upper surface
Ventral – belly or lower surface
Anterior – head or front end
Posterior – tail or hind end opposite
the head
• Oral surface (echinoderms) – is
where the mouth is located
(underside)
• Aboral surface (echinoderms) – is
opposite the mouth (top side)
Surfaces (Most Animals)
DORSAL
POSTERIOR
ANTERIOR
VENTRAL
Surfaces (Echinoderms)
ORAL
ABORAL
mouth
Symmetry
Body Symmetry
Body Symmetry
• Symmetry is the
arrangement of body
parts around a
central plane or axis
• Asymmetry occurs
when the body can’t
be divided into
similar sections
(sponges)
Body Symmetry
• Radial symmetry occurs when
body parts are arranged around
a central point like spokes on a
wheel (echinoderms)
• Most animals with radial
symmetry are sessile
(attached) or sedentary (move
very little)
Body Symmetry
• Bilateral symmetry occurs when
animals can be divided into
equal halves along a single plane
• Organisms will have right and
left sides that are mirror
images of each other
• More complex type of
symmetry
Body Symmetry
• Animals with bilateral symmetry
are usually motile
• Animals have an anterior and
posterior ends
• Show cephalization
(concentration of sensory
organs on the head or anterior
end)
Segmentation
Segmentation
• Occurs whenever animal bodies are
divided into repeating units or
segments
• Found in more complex animals
• Earthworms show external
segmentation
• Humans show internal segmentation
(backbone)
• Segments may fuse (cephalothorax)
Segmentation
cephalothorax
Tissues
Tissue Development
• Zygote (fertilized egg)
undergoes rapid cell divisions
called cleavage
• Forms a hollow ball of cells called
the blastula
Blastula
•The blastocoel is the center cavity
of the blastula with 1 germ layer
(blastoderm)
Tissue Development
• The blastula
INVAGINATES
(folds inward at one
point)
• Called Gastrulation
• The opening is
called the
blastopore
• The center is the
primitive gut or
Archenteron
Archenteron
blastopore
Tissue Development
• Blastopore may become the
mouth (Protostome) or anus
(Deuterostome)
• Protostomes (mollusks,
arthropods, & annelids)
• Deuterostomes (echinoderms &
vertebrates)
• Some animals form a middle
germ layer called mesoderm
Embryonic Development
Germ Layers
• Form tissues, organs, &
systems
• NOT present in sponges
• Ectoderm (outer) – forms
skin, nerves, sense
organs
• Endoderm (inner) – forms
liver and lungs
• Mesoderm (middle) –
forms muscles & other
systems
Body Layers
• Sponges have NO tissues or
organs, only specialized cells
• Cnidarians like jellyfish & coral
have only two body layers &
one body opening (mouth/anus)
into gastrovascular cavity
• Cnidarians have outer epidermis
& inner gastrodermis with jellylike mesoglea between the
layers
Body Layers
• All worms,
mollusks,
arthropods,
echinoderms, and
vertebrates have
three cell layers
– Ectoderm
– Endoderm
– mesoderm
Embryonic Cleavage
Cleavage
• Cleavage – rapid mitosis
(cell division) of zygote
• Radial Cleavage – cells
divide parallel or
perpendicular to axis to
each other
Cleavage
• Spiral Cleavage –
cellular divisions occur
diagonally, in a
twisting pattern
Stages of Development
Larval Forms
•
•
•
•
Animals with Indirect development
Go through immature (larval) forms
Larva does NOT resemble adult
Cnidarian (jellyfish, coral, & sea
anemone) larva called Planula
Larval Forms
• Mollusk (squid & octopus) larva
called trochophore
• Echinoderm (starfish) larva is
called Dipleurula
Metamorphosis
• Usually found in arthropods
• May be complete or incomplete
• Incomplete Metamorphosis:
egg
nymph
adult
• Complete Metamorphosis:
egg
larva
pupa
adult
Metamorphosis
COMPLETE
INCOMPLETE
Body Cavities
Coelom - Body Cavity
• Internal body cavity fully lined
with mesoderm
• Body organs suspended in this
cavity
Coelom - Body Cavity
• Acoelomate animals have solid
bodies filled with cells
• Acoelomate animals include
sponges, cnidarians, & flatworms
Coelom - Body Cavity
• Pseudocoelomate animals
(roundworms) have a functional
body cavity NOT fully lined
with mesoderm
Animal Systems
Support Systems
• Spongin & spicules (sponges)
• Limestone cases (corals)
• Exoskeletons of Chitin
(arthropods)
– Must be shed or molted to grow
• Inner Calcium plates or Test
(echinoderms)
• Bone/cartilage endoskeleton
(vertebrates)
Digestive Systems
• All animals are ingestive
heterotrophs
• Choanocytes (specialized cells)
capture & digest food for
sponges
• Gastrovascular cavity with one
opening in cnidarians and
flatworms for food to enter &
leave; called two-way digestive
system
Two-Way Digestion
Digestive Systems
• Animals with a one-way digestive
system have a mouth and an anus
• Food enters the mouth, continues
in one direction through the
digestive tract, and wastes leave
through the anus
• Includes annelids, arthropods, &
vertebrates
One-Way Digestion
Mouth
anus
Circulatory Systems
• Transports oxygen & nutrients
to cells
• Carries away wastes & carbon
dioxide from cells
• Sponges, cnidarians, &
flatworms do NOT have
circulatory systems
Circulatory Systems
• In closed circulation, blood
remains inside blood vessels
until it reaches cells (annelids &
vertebrates)
• In open circulation, blood is
pumped out of blood vessels to
bathe tissues in the body
cavity or hemocoel (arthropods
& mollusks)
Open
Circulation
Closed
Circulation