Transcript Essentials of Biology Sylvia S. Mader

Essentials of Biology
Sylvia S. Mader
Chapter 19
Lecture Outline
Prepared by: Dr. Stephen Ebbs
Southern Illinois University Carbondale
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
19.1 Evolution of Animals
• Animals are chemoheterotrophic, sexuallyreproducing eukaryotes.
• Animals have two tissues that differ from other
multicellular eukaryotes.
– Muscle tissue
– Nervous tissue
• The specialized tissues and organs of animals
arise from complex changes that occur during
development.
The Evolutionary Tree of
Animals
• Our understanding of animal evolution is based
upon the limited fossil record.
• There are also seven evolutionary trends that
appeared during animal evolution.
–
–
–
–
–
–
–
Multicellularity
True tissues and germ layers in the embryo
Bilateral symmetry
Body cavities
Coelomates
Segmentation
Jointed appendages
19.2 Introducing the
Invertebrates
• There are several groups of organisms
that comprise the invertebrates.
– Sponges
– Cnidarians such as Hydra
– Flatworms
– Nematodes and roundworms
Sponges: Multicellularity
• Sponges are aquatic,
multicellular, radiallysymmetric, filter-feeding
organisms.
• The interior of the
sponge is lined with
collar cells that engulf
food particles.
• Sponges can
reproduce asexually or
sexually.
Sponges: Multicellularity (cont.)
Cnidarians: True Tissues
• Cnidarians are radially-symmetric invertebrates
with a ring of stinging cells (cnidocytes).
• Cnidarians have two developmental germ layers
during development.
– Ectoderm
– Endoderm
• Cnidarians also have two basic body forms.
– The tubular, sedentary polyp
– The jellylike medusa
Cnidarians: True Tissues (cont.)
Flatworms: Bilateral Symmetry
• Flatworms show bilateral symmetry and
have several body systems.
– Ladderlike nervous system with cephalization.
– A digestive system with a muscular pharynx
and a gastrovascular cavity
– An excretory system provided by flame cells
– Hermaphroditic reproduction
• Flatworm can be free-living or parasitic.
Flatworms: Bilateral Symmetry
(cont.)
Roundworms: Pseudocoelomates
• Roundworms evolved a complete tube-within-atube digestive tract and a pseudocoelom.
• Roundworms lack a skeletal system but use the
fluid-filled coelom for support and movement.
• Roundworms are nonsegmented with a smooth
outside body wall.
• Roundworms can be free-living or parasitic.
Roundworms: Pseudocoelomates
(cont.)
19.3 Protostomes and
Deuterostomes Compared
• The difference between these two groups
involves the developmental fate of the first
embryonic opening.
– In protostomes, this opening becomes the mouth.
– In deuterostomes, this opening becomes the anus.
• There are three groups of organisms that are
protostomes.
– Molluscs
– Annelids
– Arthropods
19.3 Protostomes and
Deuterostomes Compared (cont.)
19.3 Protostomes and
Deuterostomes Compared (cont.)
Molluscs
• The body of a mollusc has three regions.
– The visceral mass
– The muscular foot
– The mantle, which may secrete a shell
• There are three main groups of molluscs.
– Gastropods
– Cephalopods
– Bivalves
Molluscs (cont.)
Molluscs (cont.)
• Gastropods, which means stomachfooted, include the snails and conchs.
• Gastropods can be either herbivores or
carnivores.
Molluscs (cont.)
Molluscs (cont.)
• Cephalopods, meaning head-footed,
include the octopi, squid, and nautiluses.
• Cephalopods uses tentacles to seize prey
and a beak and radula to tear apart food.
• Cephalopods have a large brain, extensive
nervous system, and highly developed
eyes.
Molluscs (cont.)
Molluscs (cont.)
• The bivalves are the clams, scallops, and
mussels.
• Bivalves have a muscular foot that can be
projected from the shell for movement.
• Bivalves are generally filter feeders, using
an incurrent siphon to bring in food.
Molluscs (cont.)
Annelids: Segmented Worms
• Annelids have segments divided by septa.
• The digestive system of annelids has several
specialized organs.
• Annelids have a closed circulatory system with
several hearts and blood vessels.
• Tubules called nephridia collect wastes and
excrete them from the worm’s body.
Annelids: Segmented Worms
(cont.)
Annelids: Segmented Worms
(cont.)
Arthropods: Jointed Appendages
• The success of arthropods can be linked
to five key characteristics.
– An exoskeleton that can be shed
– Segmentation and jointed appendages
– A well-developed nervous system
– A variety of respiratory organs
– Metamorphosis
Arthropods: Jointed Appendages
(cont.)
Arthropods: Jointed Appendages
(cont.)
Arthropods: Jointed Appendages
(cont.)
• Crustaceans are arthropods such as
shrimp, crabs, crayfish and lobsters.
• All crustaceans share several features.
– A head with five appendages
– Legs attached to the thorax
– A fused head and thorax (cephalothorax)
– Abdominal segments with swimmerets.
Arthropods: Jointed Appendages
(cont.)
• There are a wide variety of other
arthropods, each with their own unique
structures.
– Arachnids such as spiders, scorpions, ticks,
mites, and horseshoe crabs
– Millipedes and centipedes
– Insects
19.5 Echinoderms and Chordates
• There are two groups of organisms that
are deuterostomes.
– Echinoderms
– Chordates
Echinoderms
• Echinoderms such as sea stars, sea cucumbers,
and sea urchins often show radial symmetry.
• The nervous system is a network of nerves in a
ring around the mouth and stretching outward
radially.
• Locomotion is provided by a water vascular
system and tube feet.
• The water vascular system is also the
respiratory, circulatory, and excretory systems.
Echinoderms (cont.)
Chordates
• Chordates display
four traits at some
point in their life cycle.
– A dorsal supporting
rod called a notochord
– A dorsal tubular nerve
cord such as the
spinal cord
– Pharyngeal pouches
– A tail
The Invertebrate Chordates
• In the invertebrate chordates, the
notochord persists rather than being
replaced with a vertebral column.
• There are two examples of invertebrate
chordates, both of which retain the four
chordate characteristics as adults.
– The tunicates, or sea squirts
– The lancelets
Evolutionary Trends Among the
Chordates
• As the invertebrate chordates evolved,
major changes can be from one group of
chordates to the next.
– Evolution of vertebrae
– Evolution of the jaw
– Evolution of lungs for land colonization
– Jointed appendages for movement
– Amniotic eggs with adaptations for
development on land
– Hair and mammary glands
Fishes: First Jaws and Lungs
• There are three classes
of fish.
– Jawless fish
– Cartilaginous fish
– Bony fish
• The last remaining
jawless fishes are the
hagfishes and lampreys.
Fishes: First Jaws and Lungs
(cont.)
• The cartilaginous fishes, such as the sharks,
rays, and skates, have skeletons comprised of
cartilage.
• Sharks have three highly developed senses that
help them hunt for prey.
– The ability to sense electrical currents in water
– The lateral line cells along the body, which sense
differences in pressure
– A keen sense of smell
Fishes: First Jaws and Lungs
(cont.)
• Most bony fishes are ray-finned fishes, using fins
for balance and movement.
• The ray-finned fishes use a swim bladder to
adjust their buoyancy in the water.
• The bony fishes also have scales that protect
the body.
• The circulatory system of bony fishes is a single
circuit.
Fishes: First Jaws and Lungs
(cont.)
• The lobe-finned fishes are bony fishes that
have fleshy appendages and lungs.
• The lobe-finned fishes were the ancestors
of the amphibians.
Amphibians: Jointed Vertebrate
Limbs
• The amphibians evolved a number of
features that were different from the lobefinned fishes.
– Eyelids
– Ears
– A larynx, or voice box
– Larger brains
– A three-chambered heart
Amphibians: Jointed Vertebrate
Limbs (cont.)
Amphibians: Jointed Vertebrate
Limbs (cont.)
Amphibians: Jointed Vertebrate
Limbs (cont.)
• Modern amphibians include the frogs,
toads, newts, and salamanders.
• The term amphibian describes their
lifestyle as both aquatic and terrestrial.
– Larval stages live in the water.
– The adult lives on land but may return to
water to reproduce.
Amphibians: Jointed Vertebrate
Limbs (cont.)
Reptiles: Amniotic Egg
• Modern reptiles include the turtles, crocodiles,
snakes, and lizards.
• Reptiles are covered with scales for protection
from dehydration and predators.
• The tongues of reptiles also evolved to become
a sense organ.
• Reptiles also have a four chambered heart and
well developed lungs.
Reptiles: Amniotic Egg (cont.)
• Reptile reproduction also evolved to be
completely terrestrial and free from water.
• Fertilization of the eggs occurs inside the female
body.
• The amniotic egg and its extraembryonic
membranes provide nutrients, protect the
embryo, and facilitate waste and gas exchange.
Reptiles: Amniotic Egg (cont.)
Birds: Feathers
• The most unique character of birds is the
presence of feathers, which evolved from
scales.
• The anatomy of birds is designed for flight.
– The forelimbs of birds are wings.
– The bones of birds are hollow and light due to
the presence of air cavities.
Birds: Feathers (cont.)
• Birds have a four chambered heart like
mammals and are endothermic.
• Birds have highly developed nervous systems
and eyes.
• Birds are subdivided into groups based on
specific characters.
–
–
–
–
Type of beak
Type of foot
Habitat
Behavior
Mammals: Hair and Mammary
Glands
• Mammals appeared during the time of the
dinosaurs, but did not flourish until after
dinosaurs became extinct.
• Mammals share two common characters.
– Hair
– Milk-producing mammary glands
• Animals are also endothermic.
Mammals: Hair and Mammary
Glands (cont.)
• Monotremes such as the platypus were
the earliest mammals.
• Like birds, monotremes have a cloaca, a
chamber at the end of the digestive tract
for feces, excretory wastes, and sex cells.
• Monotremes are egg-laying mammals.
Mammals: Hair and Mammary
Glands (cont.)
• Marsupials have a pouch in which their
immature young develop.
• All other mammals are placental
mammals.
• The placenta is a highly modified
extraembryonic membrane that facilitates
exchange of gases, nutrients, and wastes.
19.6 Human Evolution
• The primates evolved from a common ancestor.
• There are two suborders of primates.
– The prosimians include lemurs and lorises.
– The anthropoids include monkeys, apes, and
humans.
• There are two prominent aspects of primate
evolution.
– The opposable thumb
– Larger and more complex brains
Evolution of Hominids
• There have been several bipedal hominids
that may have been human ancestors.
– The primitive australopithecines
– Homo habilis, the first hominid to use tools
and possibly to speak
– Homo erectus, the first hominid to use fire and
advanced tools.
Evolution of Modern Humans
• The ancestral hominid from which modern
humans evolved is not clear, but at least
two hypotheses have been offered.
– The multiregional hypothesis proposes that
humans evolved separately from H. erectus in
different regions and then later interbred.
– The out-of-Africa hypothesis proposes that
humans evolved from the H. erectus in Africa,
and then migrated across the globe.
Evolution of Modern Humans
(cont.)
Evolution of Modern Humans
(cont.)
Neanderthals
• Neanderthals were a group of European
hominids that may have been present when
modern humans were evolving.
• Neanderthals showed a complex culture and
tool-making ability.
• Neanderthals eventually either became extinct
or may have interbred with humans.
Cro-Magnons
• Cro-magnons are the closest evolutionary
ancestor to humans.
• Cro-magnons also demonstrated a
complex culture and may have used a
spoken language.
• Cro-magnons not only made tools, but
crafted artwork as well.
Cro-Magnons (cont.)