Introduction to animals

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Introduction to animals
Introduction to Animals
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Traits
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Characteristics of Animals

• All multicellular (metazoans)
• Eukaryotes (cells with nucleus organelles)
• Ingestive heterotrophs (take in food and
  internally digest it)
• Store food reserves in the liver as glycogen

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Lions Feeding (Ingestion)
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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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2 Divisions
Invertebrates animals without a backbone (95
of all animals) Vertebrates animals with a
backbone
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Invertebrate Phyla

• Porifera sponges
• Cnidaria sea anemones, hydra, jellyfish, coral
• Platyhelminthes flat worms
• Nematoda round worms
• Annelida segmented worms, leeches
• Mollusca univalves, bivalves, octopi, squid
• Arthropoda insects, spiders, crustaceans,
  millipedes, centipedes
• Echinodermata starfish, sea urchins, sea
• cucumbers

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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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Sponge - Porifera
Osculum of Sponge
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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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Flatworms - Platyhelminthes
Marine Flatworm
Planarian
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Roundworms (Nematoda) and Segmented Worms
(Annelida)
Nematode
Leech (segmented worm)
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Mollusca (With and Without Shells)
snail
scallop
octopus
nudibranch
nautilus
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Arthropoda (insects, spiders, crustaceans,
horseshoe crab)
spider
crayfish
Horseshoe crab
Dung beetle
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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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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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