Transcript Chapter 03
Chapter 19
The Animal Kingdom
What Is an Animal?
Multicellular heterotrophs Lack a cell wall Motile during some stage in life Able to respond rapidly to external stimuli Able to reproduce sexually
2
Animal Evolution
Most animal phyla currently populating the Earth were present by the Cambrian period (544 million years ago) The scarcity of pre-Cambrian fossils led systematists to search for clues about the evolutionary history of animals by examining features of
• • •
Anatomy Embryological development DNA sequences
3
Animal Evolution
Certain features represent evolutionary milestones
• • •
The appearance of tissues The appearance of body symmetry Protostome and deuterostome development These features mark major branching points on the animal evolutionary tree
4
The Appearance of Body Symmetry
Symmetrical animals have an upper (dorsal) surface and a lower (ventral) surface Animals with tissues exhibit either radial or bilateral symmetry
Animals with radial symmetry can be
divided into roughly equal halves by any plane that passes through the central axis
5
6
Body Symmetry and Cephalization (a) Radial Central Axis Symmetry A Radial Plane Sagittal Plane Anterior Another Radial Plane (b) Bilateral Posterior Symmetry
Body Cavities
Acoelomate animals lack a body cavity
•
e.g. flatworms
7
Body Cavities: The Acoelomates Cnidaria No cavity between body wall & digestive tract
8
Digestive Cavity Digestive Lining Solid Tissue Body Wall
Body Cavities
Pseudocoelomate animals possess a
pseudocoelom (a fluid-filled body cavity
that is not completely lined with mesoderm)
•
e.g. nematodes (roundworms)
9
Body Cavities: The Pseudocoelomates Nematoda
10
Body cavity partially lined with mesoderm Digestive Cavity Digestive Tract Pseudocoelom Partial Lining Body Wall
Body Cavities
Coelomate animals possess a coelom (a
fluid-filled body cavity that is completely lined with mesoderm)
•
e.g. annelids, arthropods, mollusks, echinoderms, chordates
11
Body Cavities: The True Coelomates Annelida
12
Body cavity completely lined with mesoderm Digestive Cavity Digestive Tract Coelom Complete Lining Body Wall
Embryological Development
Bilateral animals can be divided into two main groups based on embryological development Protostomes
•
Body cavity forms within a space between the body wall and the digestive cavity
•
e.g. nematodes, arthropods, flatworms, annelids, mollusks Deuterostomes
•
Body cavity forms as an outgrowth of the digestive cavity
•
e.g. echinoderms, chordates
13
Chapter 22 14
No true tissues True tissues No body cavity 2 tissue layers; radial symmetry Deuterostome development Protostome development Coelom Pseudocoel Body cavity 3 tissue layers; bilateral symmetry Evolutionary Tree of Major Animal Phyla
•
The Invertebrate Phyla: Porifera Phylum Porifera: the sponges Simple single-celled organisms living together
15 • •
Low specialization of cells; no tissue level Asymmetrical ::::: Reproduce by budding Three major types of cells
•
Epithelial cells (cover outer body surface)
– Some are modified into pore cells (regulate flow of water
through pores)
• •
Collar cells (flagellated cells that maintain water flow through the sponge) Amoeboid cells (motile cells that digest and distribute nutrients, produce reproductive cells, and secrete spicules)
Epithelial Cell Spicules Amoeboid Cells Pore Cell Collar Cell Osculum
16
Pore Water Flow The Body Plan of Sponges
Chapter 22
The Invertebrate Phyla: Cnidaria Phylum Cnidaria: the hydra, anemones, & jellyfish – Radial symmetry
•
Cells organized into distinct tissues
• • • • •
Rudimentary nerve network and contractile tissue No true organs Two distinct body plans:
–Polyp, attached –Medusa, free swimming
One digestive opening Reproduce sexually and asexually
17
Cnidarian Body: The Polyp Mouth Tentacle
18
Body Wall Mesoglea Gastrovascular Lining Column Foot Gastrovascular Cavity
Body Wall Cnidarian Body: The Medusa Mesoglea
19
Gastrovascular Cavity Tentacle Gastrovascular Lining Mouth
Cnidarian Weaponry: The Cnidocyte Trigger Filament Armed Cnidocyte Spent Cnidocyt e Body Wall Nuclei Water
20
The Invertebrate Phyla: Platyhelminthes The flatworms
•
Development of bilateral symmetry
•
Ability to move forward using aggregations of nerve cells, ganglia
•
True organs begin to evolve
•
Most are hermaphroditic (can self-fertilize)
•
Many are free living—planarians
•
Some are parasitic—tapeworm and fluke
21
22
Flatworm Organ Systems (a) Digestive System Pharynx (b1) Excretory System Excretory Canal Gastrovascula r Cavity Excretory Pore (b2) Nervous System Nerve Cord Brain
Egg-filled segments are shed from worm & passed in human feces.
Tapeworm matures in human intestine, producing a series of reproductive segments.
vessels to pig muscles & encyst there. Life Cycle of Human Pork
23
Tapeworm Larvae hatch in pig intestine Measly pork marketed for human consumption.
infected feces
The Invertebrate Phyla: Nematoda (Round Worms) Advanced gastrovascular cavity (are bilateral)
• •
Tubular Two openings Advanced sensory "ganglionic brain" Lack circulatory and respiratory systems Depend on diffusion for gas exchange Sexual reprouction Most are harmless - Some parasitic
24
Heartworms in the Heart of a Dog Open heart of dog Female heartworms
25
The Invertebrate Phyla: Annelida (Segmented Worms) Bilateral symm. Repeating rings identical nerve ganglia Excretory structures Advanced locomotion ability Fluid-filled body cavity—coelom; involved in locomotion (hydrostatic skeleton) Sexual Repro. Some hermaphrodites Closed circulatory system Evolved many rudimentary organ systems
•
Nervous, excretory, circulatory, muscular
•
Compartmentalized digestive tract
26
Coelom An Annelid: the Earthworm Ventral Nerve Cord Brain Ventral Nerve Cord Coelo m Gizzard
27
Excretory Pore Anus Mouth Pharynx Ventral Vessel Hearts Esophagus Crop Intestine
The Invertebrate Phyla: Arthropoda
28
The most numerous in numbers & species Evolutionary adaptations allow them to reside in diverse environments
•
Paired, Jointed legs
• • • • • •
Exoskeleton for water conservation and support Segmentation Well-developed sensory and nervous systems Efficient gas-exchange (gills, trachea, book lungs) Well-developed (open) circulatory systems Sense organs – compound eyes Reside in both aquatic and terrestrial habitats
Major Arthropod Classes: Insecta 800,000 species Have three pairs of legs
•
Usually two pairs of wings
•
Make escape from predators easier Metamorphosis eliminates competition for food between generations The importance of insects
29
Major Arthropod Classes: Arachnida 50,000 species
•
Spiders
•
Mites
•
Ticks
•
Scorpions Eight walking legs Carnivorous Simple eyes with a single lens
30
Major Arthropod Classes: Crustacea 30,000 aquatic species
•
Crabs
• • •
Crayfish Lobster Shrimp Barnacles
•
Size varies from microscopic to 12 feet (3.7 m) Vary in number of appendages Have two pairs of antennae Generally with compound eyes Exchange gases using gills
31
Insect Body Plan Head Thorax Abdomen
32
Antennae Compound Eyes Wing Mouth Parts
The Invertebrate Phyla: Mollusca (Snails & Clams) Bilateral Symmetry Coelomate Moist muscular body without a skeleton Found in aquatic or moist terrestrial habitats Body protected by limy shell or obnoxious taste Complex, concentrated, ganglionic brain Open circulatory system Classes
• •
Gastropoda—snails and sea slugs Pelecypoda— scallops, oysters, mussels, & clams
•
Cephalopoda—octopuses, squid, nautiluses
33
34
Tentacle A Generalized Mollusk Eye Ganglia (brain) Digestive Tract Gonad Heart Coelom Shell Mantle Anus Foot Radula Mouth Gill Nerve Cords
The Invertebrate Phyla: Echinodermata (Sea Stars, Urchins) Bilateral as larvae – Radial as adult Deuterostome development Coelomate Possesses an endoskeleton of CaCO 3 Lack a head and circulatory system Simple nervous system; no distinct brain Water-vascular system for slow movement Can regenerate lost parts
35
Water-Vascular System of Echinoderms Sieve Plate Ampulla Canals Plates of Endoskeleton Photo (ventral) A Mussel (clam)
36
Tube Feet
Key Features of Chordates
Notochord •
Stiff flexible rod extending the length of the body
Dorsal, hollow nerve cord •
Expands anteriorly to form brain
Pharyngeal gill slits •
May form respiratory organs or may appear as grooves
Post-anal tail •
Extends past the anus
37
Are Humans Chordates?
Only one chordate characteristic, the nerve cord, is present in adult humans; however, human embryos exhibit all four…
• • •
Tail will disappear completely Notochord is replaced by the backbone Gill slits (grooves) contribute to the formation of the lower jaw
38
Chapter 22 39
The Vertebrates: Chordata, Vertebrata Subphyla
• •
Invertebrates—lancelets and tunicates
–Lack a head and backbone –marine habitat
Vertebrates
–Only 2.5% of extant animals –Backbone –Seven Major Classes 40
The Lancelet: An Invertebrate Chordate Nerve Cord Notochord Muscle Segments Tail Gill Slits Gut
41
Mouth Anus
Heart The Tunicate: An Invertebrate Chordate Brain Mouth Water Exit ADULT Gill Slits
42
Gut Nerve Cord LARVA Notochord
The Vertebrate Classes: Agnatha & Chondrichthyes
43
Agnatha—jawless fish
• • •
Skeleton of cartilage and eellike shape Unpaired fins, lack scales Slimy skin perforated by circular gill openings Chondrichthyes
• • • •
“Cartilaginous fishes”—sharks, skates, & rays Leathery skin Respire by gills Two-chamber heart
A Hagfish
44
Lobe-Finned Fishes
Lungfish are found in freshwater habitats Have both gills and lungs Tend to live in stagnant waters low in oxygen Lungs allow them to supplement their supply of oxygen by breathing air directly
45
Lobe-Finned Fishes
Some species can survive even if the water dries up
•
Burrow into mud, Seal themselves in a mucous-lined chamber and breathe through lungs as metabolic rate slows, Resume underwater life when rains return and pool refills
46
47
The Vertebrate Classes: Osteichthyes “Bony fishes” Varied forms Supplemental lungs for freshwater living Fleshy fins
48
The Vertebrate Classes: Amphibia Bony support for the body Waterproofing for the skin and eggs Moist protection of respiratory membranes Development of adult lungs Cold Blooded --- External Fertilization Still need aquatic habitat for reproduction 3 chambered heart
49
Amphibians Live a Double Life
Include frogs, toads, and salamanders “Double life” of amphibians
• •
Begin life adapted to aquatic environment (eg tadpoles have gills) Mature into semiterrestrial adult with lungs
50
51
The Vertebrate Classes: Reptilia Turtles, alligators, crocodiles, dinosaurs, birds
52
Respire through Lungs Internal fertilization Shelled amniotic egg (encapsulates embryo in a
liquid filled membrane, the amnion)
Skeleton modified for better support and locomotion
Birds
Appeared in the fossil record about 150 million years ago Considered by modern systematists to be feathered reptiles
•
The earliest known bird, Archaeopteryx
53
54
Birds
Distinctive group of “reptiles” adapted for flight
• • • •
Feathers (provide lift and control as well as insulation) Hollow bones (reduce weight of skeleton) Females have a single ovary Shelled egg (frees female from carrying developing offspring) Maintain a constant body temperature (warm-blooded)
55
The Vertebrate Classes: Mammalia Warm-blooded Four-chambered heart Fur for insulation and protection Legs for running fast to avoid predators Mammary glands to nurse live-born young Complex cerebral cortex—increased learning ability Includes
•
Egg-laying monotremes (platypus)
• •
Marsupials (opossums, koalas, kangaroos) Placental mammals (most other mammals)
56
Mammals
Appeared in the fossil record about 250 million years ago Did not diversify and dominate terrestrial habitats until the dinosaurs became extinct (65 million years ago)
57
Bats, the Only Flying Mammals
58