1
Q
Animals share these major characteristics:
A
- Heterotrophs
- Multicellular
- Cells without cell walls
- Able to move
2
Q
General features of animals:
A
- Diverse in form and habit
- Most reproduce sexually
- Have a characteristic pattern of embryonic development
- Cell of all animals (except sponges) are organized into tissues
3
Q
5 key transitions noted in animal evolution:
A
- Tissues
- Symmetry
- Body cavity
- Development
- Segmentation
4
Q
Evolution of tissues
A
- Parazoa (Sponges) lack defined tissues and organs, disaggregate and aggregate their cells
- Eumetazoa (all other animals) have distinct and well-defined tissues, have irreversible differentiation for most cell types
5
Q
Evolution of symmetry
A
- Sponges lack definite symmetry
- Eumetazoa have a symmetry defined along an imaginary axis drawn through the animal’s body
- 2 main types of symmetry (radial and bilateral)
6
Q
Radial symmetry
A
- Body parts arranged around central axis
- Can be bisected into two equal halves in any 2-D plane
7
Q
Bilateral symmetry
A
- Body has right and left halves that are mirror images
- Only the sagittal plane bisects the animal into two equal halves
8
Q
Bilateral symmetry has 2 advantages over radial symmetry:
A
- Cephalization- Evolution of a definite brain area
2. Greater mobility
9
Q
Evolution of a body cavity
A
- Eumetazoa produce three germ layers
- Outer ectoderm (body coverings and nervous system)
- Middle mesoderm (skeleton and muscles)
- Inner endoderm (digestive organs and intestines)
- Body cavity = Space surrounded by mesoderm tissue that is formed during development
- Three basic kinds of body plans
- Acoelomates = No body cavity
- Pseudocoelomates = Body cavity between mesoderm and endoderm
- Called the pseudocoel
- Coelomates = Body cavity entirely within the mesoderm
- Called the coelom
10
Q
Evolution of a body cavity (continued)
A
- The body cavity made possible the development of advanced organs systems
- Coelomates developed a circulatory system to flow nutrients and remove wastes
- Open circulatory system: blood passes from vessels into sinuses, mixes with body fluids and reenters the vessels
- Closed circulatory system: blood moves continuously through vessels that are separated from body fluids
11
Q
Evolution of different patterns of development
A
-The basic Bilaterian pattern of development:
-Mitotic cell divisions of the egg form a hollow ball of cells, called the blastula
-Blastula indents to form a two-layer- thick ball with:
-Blastopore = Opening to outside
-Archenteron = Primitive body cavity
Bilaterians can be divided into two groups:
-Protostomes develop the mouth first from or near the blastopore
-Anus (if present) develops either from blastopore or another region of embryo
-Deuterostomes develop the anus first from the blastopore
-Mouth develops later from another region of the embryo
12
Q
Evolution of different patterns of development (continued)
A
Deuterostomes differ from protostomes in three other fundamental embryological features:
-1. Cleaveage pattern of embryonic cells
-Protostomes = Spiral cleavage
-Deuterostomes = Radial cleavage
-2. Developmental fate of cells
-Protostomes = Determinate development -Deuterosomes = Indeterminate development
-3. Origination of coelom
-Protostomes = Forms simply and directly from the mesoderm
-Deuterostomes = Forms indirectly from the archenteron
Deuterostomes evolved from protostomes more than 500 MYA
13
Q
Evolution of Segmentation
A
- Segmentation provides two advantages
- Allows redundant organ systems in adults such as occurs in the annelids
- Allows for more efficient and flexible movement because each segment can move independently
- Segmentation appeared several times in the evolution of animals
14
Q
Evolution of Segmentation (continued)
A
Multicellular animals, or metazoans, are traditionally divided into 36 or so distinct phyla based on shared anatomy and embryology
Metazoans are divided into two main branches:
-Parazoa = Lack symmetry and tissues
-Eumetazoa = Have symmetry and tissues
-Diploblastic = Have two germ layers
-Triploblastic = Have three germ layers
15
Q
Molecular systematics
A
Uses unique sequences within certain genes to identify clusters of related groups
16
Q
Most new phylogenies agree on two revolutionary features:
A
- Separation of annelids and arthropods into different clades
- Division of the protostome group into Ecdysozoa and Spiralia
- The latter is then broken down into Lophotrochozoa and Platyzoa
17
Q
3 layers of porifera
A
- Outer epithelium
- Mesohyl
- Choanocytes
18
Q
Arthropoda
A
- By most successful animals
- Affect all aspects of human life
19
Q
4 extant classes of arthropods
A
- Chelicerata
- Crustacea
- Hexapoda
- Myriapoda
20
Q
Arthropod morphology
A
- Segmentation
- Exoskeleton
- Jointed appendages
21
Q
Phylum Mollusca
A
- Second in diversity only to arthropods
- Snails, slugs, clams, octopuses
- Some have shell, some do not
- Evolved in oceans
22
Q
Mollusk body plan
A
- Mantle
- Foot
- Internal organs
23
Q
Classes of Mollusks
A
- Polyplacophora – Chitons
- Gastropoda – limpets, snails, slugs
- Bivalvia – clams, oysters, scallops
- Cephalopoda – squids, octopuses, cuttlefishes, and chambered nautilus
24
Q
5 extant classes of Phylum Echinodermata
A
- Asteroidea (sea stars and sea daisies)
- Echinoidea (sea urchins and sand dollars)
- Ophiuroidea (brittle stars)
- Crinoidea (sea lilies and feather stars)
- Holothuroidea (sea cucumbers)
25
Phylum chordata
- Deuterostome coelomates
- Nearest relatives of echinoderms
- Fishes, amphibians, reptiles, birds, and mammals
26
4 features of phylum chordata
1. Nerve cord
2. Notochord
3. Pharyngeal slits
4. Postanal tail
27
Phylum chordata are divided into 3 subphyla
1. Urochordata (nonvertebrates)
2. Cephalochordata (nonvertebrates)
3. Vertebrata
28
Fishes have these characteristics:
1. Vertebral column
2. Jaws and paired appendages
3. Internal gills
4. Single-loop blood circulation
5. Nutritional deficiencies
29
History of fishes
- First fishes had mouths with no jaws
- Development of jaws occurred in the late Silurian period
- Armored fishes (placoderms) and spiny fishes both had jaws
- At the end of the Devonian period, essentially all of these pioneer vertebrates disappeared, replaced by sharks and bony fishes in one of several mass extinctions
- Sharks and bony fishes first evolved in the early Devonian, 400 MYA
- Jaw was improved even further allowing the mouth to open much wider than was previously possible
30
Class Chondrichthyses
- Sharks, skates, rays
- Became the dominant sea predators in the Carboniferous period (360–280 MYA)
- Cartilage skeleton “calcified” with granules of calcium carbonateSharks were among the first vertebrates to develop teeth
- Sharks were among the first vertebrates to develop teeth
- Sharks (and bony fishes) have a fully developed lateral line system
- Reproduction in sharks differs from that of other fishes
- Sharks have long gestation periods and relatively few offspring
31
Bony fishes
- Evolved at the same time as sharks about 400 MYA
- Bony fishes are the most species-rich group of all vertebrates (> 30,000 living species)
- Significant adaptations include swim bladder and gill cover
32
Two major groups of bony fishes
- Ray-finned fishes
| - Lobe-finned fishs
33
Class Amphibia
- First vertebrates to walk on land
| - Direct descendent of fishes
34
5 distinguishing amphibian features
1. Legs
2. Lungs
3. Cutaneous respiration
4. Pulmonary veins
5. Partially divided heart
35
Ichthyostega
- Amphibians evolved from lobe-finned fish
- One of the first amphibians
- Sturdy forelegs, flipper-shaped hindlimbs
- Long, broad, overlapping ribs form solid cage for lungs and heart
36
Tiktaalik
- a transitional fossil found between fish and Ichthyostega
- Had gills and scales like a fish, but a neck like an amphibian
- Shoulder, forearm, and wrist bones were like those of amphibians, but at the end of the limb was a lobed fin, rather than the toes of an amphibian
37
3 modern amphibian groups
- Order Anura ("without tail")
- Order Caudata ("visible tail")
- Order Apoda ("without legs")
38
Order Anura (frogs and toads)
- Frogs have smooth, moist skin and long legs
- Toads have bumpy, dry skin and short legs
- Eggs laid in water – lack watertight membranes
39
Order Caudata (Salamanders)
- Have long bodies, tails, and smooth, moist skin
- Live in moist places
- Eggs are fertilized internally – sperm packet
- Larvae similar to adults
40
Order Apoda (caecilians)
- Tropical, burrowing amphibians
- Legless with small eyes and jaws with teeth
- Fertilization is internal
41
All reptiles have 3 key features:
1. Amniotic eggs, which are watertight
2. Dry skin, which covers body and prevents water loss
3. Thoracic breathing, which increases lung capacity
42
The amniotic egg has four membranes:
- Chorion -- Outermost layer, allows gas exchange
- Amnion -- Encases embryo in fluid-filled cavity
- Yolk sac -- Provides food
- Allantois -- Contains excreted wastes from embryo
43
Four surviving orders of reptiles:
- Chelonia -- Turtles and tortoises
- Rhynchocephalia -- Tuartaras
- Squamata -- Lizards and snakes
- Crocodylia -- Crocodiles and alligators
44
Class Aves
- Birds are the most diverse of all terrestrial vertebrates
- Success lies in unique structure – feather
- Birds still retain many reptilian traits
- Amniotic eggs and scales on legs
- Lack teeth and tails of reptiles
45
Two major distinguishing traits of birds:
- Feathers
| - Flight skeleton
46
Archaeopteryx
- First known bird
| - Feather probably evolved for insulation
47
Birds exhibit three evolutionary novelties:
1. Feathers
2. Hollow bones
3. Physiological mechanisms for flight
48
Class Mammalia
-4500 species of mammals
49
2 fundamentally mammalian traits
1. Hair
| 2. Mammary glands
50
History of mammals
- Mammals have been around since the time of the dinosaurs, about 220 MYA
- Mammals reached their maximum diversity in the Tertiary period (65–2 MYA)
51
2 subclasses of mammals
1. Prototheria (most primitive)
- Lay shelled eggs
- Only living group is the monotremes
2. Theria
- Viviparous – young are born alive
- Two living groups
- Marsupials or pouched mammals
- Placental mammals
52
Monotremes
- Lay shelled eggs
- Like reptiles have single opening (cloaca) for feces, urine, and reproduction
- Lack well-developed nipples
- Duck-bill platypuses, and 2 echidna species
53
Marupials
- Major difference is pattern of embryonic development
- Kangaroo – isolation of Australia
- Opossum – only North American marsupial
54
Placental mammals
- Produce a true placenta that nourishes embryo throughout its development
- Includes most living mammals
55
Evolution of Primates
-Primates are the mammals that gave rise to our own species
56
Evolved two features that allowed them to succeed in an arboreal environment:
1. Grasping fingers and toes
| 2. Binocular vision
57
Earliest primates split into 2 groups:
1. Prosimians -- Lemurs, lorises, tarsiers
| 2. Anthropoids -- Monkeys, apes, humans
58
Hominoids include:
- Apes
| - Hominids (humans
59
Apes vs Hominids
- The common ancestor of apes and hominids is thought to have been an arboreal climber
- Differences related to bipedal locomotion
60
Where did humans come from?
-They evolved from Africa
61
"Out of Africa" Theory
- Humans originated from Africa
- A group migrated to other continents
- Additional fossil evidence shows modern humans lived in Africa at time of Eve
62
Australopithecines
- Weighed about 18 kg
- About 1 m tall
- Hominid dentition
- Brains no larger than those of apes
- Walked upright
63
Genus Homo
- The first humans evolved from australopithecine ancestors about 2 MYA
- Thought to be Australopithecus afarensis
- In the 1960s, hominid bones were found near stone tools in Africa
- Early humans were called homo habilis
64
Homo floresiensis
-In 2004, discovered in the tiny Indonesian Island of Flores
-Youngest fossils only 15,000 years old
-diminutive stature
-Coexisted with and preyed on a miniature species of elephant
-Believed to be more closely related to
H. erectus than to H. sapiens
65
Modern humans
- First appeared in Africa about 600,000 years ago
- Three species evolved from it:
- Homo heidelbergensis (oldest)
- Homo neanderthalensis
- Homo sapiens
66
Homo neanderthalensis
- Made diverse tools
- Took care of sick and buried dead
- First evidence of symbolic thinking
- They abruptly disappeared about 34,000 years ago
67
Homo sapiens
- Only surviving homind
- Progressive increase in brain size
- Extensive cultural experience
68
Phylum Cnidaria
- Most marine, few fresh water species
- Diploblastic
- Bodies have distinct tissues but no organs
- No concentrated nervous system
- Body plan has single opening leading to gastrovascular cavity
- 2 layers to body wall
1. Epidermis
2. Gastrodermis
- Cnidarians use nematocysts to capture prey
69
5 class of Cnidaria
1. Scyphoza (jellyfish)
2. Staurozoa (Star jellies)
3. Anthozoa (Sea anemone)
4. Cubozoa (box jellies)
5. Hydrozoa (Hydroids, hydra, Portuguese Man-of-War
70
Phylum Ctenophora
- comb jellies, sea walnuts, or sea gooseberries
- 8 rows of comblike plates of fused cilia that beat in a coordinated fashion
- Many bioluminescent
- 2 tentacles covered with colloblasts
71
Phylum Acoelomorpha
- Acoel flatworms were once considered basal members of the phylum Platyhelminthes
- Have a primitive nervous system and lack a digestive cavity
- Based on molecular evidence, similarities are convergent
72
Phylum Nematoda
- Vinegar eels, eelworms, and other roundworms
- Members of this phylum are found everywhere – abundant and diverse
- Marine, freshwater, parasites, free-living
- Bilaterally symmetrical and unsegmented
73
Phylum Annelida
- Segmented worms
- Body built of repeated units
- May not be monophyletic
74
Subphylum Urochordata
- Tunicates and salps are marine animals
- Larvae are tadpolelike and have notochord and nerve cord
- Adults typically lose the tail and notochord
75
Subphylum Cephalochordata
- Lancelets are scaleless chordates
- Notochord persists throughout animal’s life
- Spend most of their time partly buried
- Have no distinguishable head
- Feed on plankton using cilia-generated currents
- Closest relatives to vertebrates
76
Subphylum Vertebrata
- Vertebrates are chordates with a spinal column
- The first vertebrates appeared in the oceans about 545 MYA
- Jawed fishes soon became dominant
- Amphibians invaded the land
- Reptiles replaced them as the dominant land vertebrates
- Birds and mammals became dominant after Cretaceous mass extinction
biology 102
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