Introduction to animals

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Introduction to animals
Introduction to Animals
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Characteristics of Animals

• All multicellular Eukaryotes
• Heterotrophs (take in food and internally digest
  it)
• Store food reserves in the liver as glycogen

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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

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Cicada Molting Exoskeleton
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Support Systems

• Worms and echinoderms (starfish) have
  fluid-filled internal cavities giving them
  support
• Called hydrostatic skeletons

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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

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SESSILE
SEDENTARY
Chiton
Sponge
MOTILE
Cheetah
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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

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Leeches Exchange Sperm During Mating
leech
Mating
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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

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Parthenogenesis in the Komodo Dragon
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Female
Beetles Mating
Young
Courtship
Male
Mating and Mating Behaviors
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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

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Molecule or compound
Atom
Organelle
Levels of Organization
CELL
Life begins
Tissue
Organ
Organ system
Organism
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Invertebrate groups
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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

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1. Phylum Porifera(Sponges)
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Sponge - Porifera
Osculum of Sponge
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Phylum Porifera (Sponges)
(exit for water)
(skeleton)
(digest and distribute food)
Choanaocyte
Sponges are Parazoans they contain NO true
tissues Sponges are filter feeders
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2. Phylum Cnidaria

• Jellyfish, Corals, and other Stingers

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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.

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Two Body Forms

• Polyps
• - attached to a surface
• - ex sea anemones
• - mouth points up

• Medusae
• - free floating
• -ex jellyfish
• -mouth points down

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Sea Anemone - Cnidaria
Tentacles of Sea Anemone
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More Cnidarians
Brain Coral
Red jellyfish
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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.

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Flatworms - Platyhelminthes
Marine Flatworm
Planarian
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Planaria
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Tapeworm Scolex (head)
Young Proglottids
Old Proglottids
tapeworms appear to be segmented, but they are
not true segmented worms
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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.

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• (Trichinella spiralis in humans via undercooked
  infected pork)

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Nematode
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Nematode
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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.

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leech

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• 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

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• 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.

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Phylum Annelid
Polychaete Worm
Fanworm
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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.

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Snails
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Mollusca (With and Without Shells)
snail
scallop
octopus
nudibranch
nautilus
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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.

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The specialized body segments are the Head,
Thorax and Abdomen
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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
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Complete metamorphosisImmature 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 --gt larva --gt pupa --gt adult
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Arthropoda (insects, spiders, crustaceans,
horseshoe crab)
spider
crayfish
Horseshoe crab
Dung beetle
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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
• features are bilateral, as are the body shapes of
  their
• larvae.

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Echinoderms
Sea fan (crinoid)
starfish
Brittle star
Sand dollar
Sea cucumber
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Vertebrate Groups
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10. Phylum Chordata

• The Phylum Chordata consists of animals that
  exhibit the following four features. In many
  cases, these features are temporary, appearing
  only during embryonic development.

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1. A Notochord

• A notochord provides support for the body. It is
  a flexible cord located on the dorsal surface. In
  most cases, the notochord is replaced by bone
  during development.

Notochord
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2. A Dorsal Hollow Nerve Cord

• A dorsal hollow nerve cord forms the basis of the
  nervous system. In some chordates, the nerve cord
  becomes the brain and spinal cord.

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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 disappear during embryonic development.

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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.

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There are Two Groups of Chordates

• 1. Invertebrate Chordates includes lancelets and
• tunicates.
• 2. Vertebrate Chordates includes
• sharks, fish, amphibians, reptiles,
• birds and mammals. Vertebrate Chordates
  are characteristics by a series of bones, the
  vertebrae, that enclose the spinal cord.

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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

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Vertebrate Backbone
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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)

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Bone Cartilage in Fetus
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Fish
lancelet
ray
damselfish
anglerfish
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Amphibia
salamander
toad
frog
newt
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Reptilia
Turtle
Snake
Lizard
Alligator
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Birds - Aves
hummingbird
ostrich
lovebirds
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Mammalia
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Body Areas
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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)

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Surfaces (Most Animals)
DORSAL
POSTERIOR
ANTERIOR
VENTRAL
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Surfaces (Echinoderms)
ORAL
ABORAL
mouth
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Symmetry
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Body Symmetry
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Body Symmetry

• Symmetry is the arrangement of body parts around
  a central plane or axis
• Asymmetry occurs when the body cant be divided
  into similar sections (sponges)

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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)

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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

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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)

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Segmentation
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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)

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Segmentation
cephalothorax
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Tissues
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Tissue Development

• Zygote (fertilized egg) undergoes rapid cell
  divisions called cleavage
• Forms a hollow ball of cells called the blastula

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Blastula

• The blastocoel is the center cavity of the
  blastula with 1 germ layer (blastoderm)

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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
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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

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Embryonic Development
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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

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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 jelly-like mesoglea between the
  layers

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Body Layers

• All worms, mollusks, arthropods, echinoderms, and
  vertebrates have three cell layers
• Ectoderm
• Endoderm
• mesoderm

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Embryonic Cleavage
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Cleavage

• Cleavage rapid mitosis (cell division) of
  zygote
• Radial Cleavage cells divide parallel or
  perpendicular to axis to each other

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Cleavage

• Spiral Cleavage cellular divisions occur
  diagonally, in a twisting pattern

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Stages of Development
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Larval Forms

• Animals with Indirect development
• Go through immature (larval) forms
• Larva does NOT resemble adult
• Cnidarian (jellyfish, coral, sea anemone) larva
  called Planula

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Larval Forms

• Mollusk (squid octopus) larva called
  trochophore
• Echinoderm (starfish) larva is called Dipleurula

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Metamorphosis

• Usually found in arthropods
• May be complete or incomplete
• Incomplete Metamorphosis
• egg nymph adult
• Complete Metamorphosis
• egg larva pupa adult

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Metamorphosis
COMPLETE
INCOMPLETE
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Body Cavities
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Coelom - Body Cavity

• Internal body cavity fully lined with mesoderm
• Body organs suspended in this cavity

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Coelom - Body Cavity

• Acoelomate animals have solid bodies filled with
  cells
• Acoelomate animals include sponges, cnidarians,
  flatworms

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Coelom - Body Cavity

• Pseudocoelomate animals (roundworms) have a
  functional body cavity NOT fully lined with
  mesoderm

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Animal Systems
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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)

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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

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Two-Way Digestion
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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

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One-Way Digestion
Mouth
anus
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Circulatory Systems

• Transports oxygen nutrients to cells
• Carries away wastes carbon dioxide from cells
• Sponges, cnidarians, flatworms do NOT have
  circulatory systems

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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)

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Open Circulation
Closed Circulation
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