Bio Real Part 2

Front 1

What are the general characteristics of animals?

Back 1

• Multicellularity
• Heterotrophy
• Internal digestion
• Motility

Front 2

What has gene sequencing shown in animals?

Back 2

all animals have a common ancestor (monophyletic).
Synapomorphies:
• Unique junctions between cells
• A common set of extracellular molecules, including collagen and proteoglycans
• Similarities in Hox and other developmental genes

Front 3

What was probably the common ancestor of all animals?

Back 3

colonial flagellated protist

Front 4

Diploblastic- development patterns

Back 4

animals have two cell layers (ectoderm and endoderm?

Front 5

triploblastic (development pattern)

Back 5

have 3 layers of cell- ecto, endo, and mesoderm

Front 6

Gastrulation

Back 6

hollow ball of cells indents and forms a cavity, the blastopore.

Front 7

Protostomes

Back 7

blastopore develops into the mouth

Front 8

Deuterostomes

Back 8

blastopore develops into the anus; mouth develops later.

Front 9

Body plan

Back 9

general structure, arrangement of organ systems, and integrated functioning of body parts.

Front 10

Four key features of body parts

Back 10

• Symmetry
• Body cavity structure
• Segmentation
• External appendages

Front 11

Symmetry

Back 11

overall shape

Front 12

symmetrical

Back 12

it can be divided along at least one plane into similar halves.

Front 13

Asymmetrical

Back 13

no plane of symmetry (placozoans and sponges)

Front 14

Radial symmetry

Back 14

body parts arranged around a central axis.

Front 15

Bilateral symmetry

Back 15

can be divided into mirror image halves on only one plane

Front 16

what is bilateral symmetry associated with?

Back 16

cephalization—concentration of sensory organs and nerve tissues at the anterior end, or head.
The anterior end encounters the environment first. Cephalization has been evolutionarily favored.

Front 17

What can body cavities act as?

Back 17

hydrostatic skeletons
When muscles contract, fluid is pushed to another part of the cavity, which causes that region to expand.
If the animal has both circular and longitudinal muscles, it has even greater control over movement.

Front 18

Segmentation

Back 18

facilitates specialization of body regions.
Also allows animal to alter body shape and control movements precisely.
Radiation of the arthropods was based on changes in a segmented body plan.

Front 19

Bilateria

Back 19

monophyletic group that includes protostomes and deuterostomes.
• Bilateral symmetry
• Triploblastic
• At least 7 Hox genes
Four animal groups are not bilaterians: sponges, placozoans, ctenophores, and cnidarians.

Front 20

Eumetazoans-bilateria

Back 20

• Body symmetry
• A gut, and nervous system
• Tissues organized into distinct organs
Includes all animal groups except sponges and placozoans.

Front 21

Sponges:

Back 21

no distinct tissue types
Have hard skeletal elements called spicules

Front 22

Glass sponges and demosponges

Back 22

spicules made of silicon dioxide

Front 23

Calcareous sponges

Back 23

spicules made of calcium carbonate

Front 24

What is the sponge body plan?

Back 24

aggregation of cells around a water canal system.
Water and food particles enter through small pores and pass into the canal system where the choanocytes capture food particles.
Water movement results from the beating of the choanocyte flagella.

Front 25

How do most sponges get there food?

Back 25

marine filter feeders.

Front 26

How is body shape related to habitat conditions in sponges?

Back 26

In intertidal zones with strong wave action, they attach firmly to the substrate.
In flowing water, bodies are flattened and oriented at right angles to the flow, to capture food particles.

Front 27

Placozoans:

Back 27

• Four cell types; weakly differentiated tissue layers
• Flattened animals that adhere to substrates; asymmetric
• Diploblastic
• Have a swimming, pelagic stage
Some features of the very simple body plan may be secondarily derived.

Front 28

Ctenophores

Back 28

• Radial symmetry;
• Diploblastic; gelatinous extracellular matrix called mesoglea between the layers
• Move by beating cilia arranged on 8 comb-like plates called ctenes
• Complete gut; feed with tentacles that discharge sticky material to trap plankton

Front 29

Mesoglea

Back 29

gelatinous extracellular matrix

Front 30

ctenes

Back 30

move by beating cilia arranged on 8 comb like plates which are placed on this

Front 31

Cnidarians:

Back 31

• Jellyfishes, sea anemones, corals, hydrozoans
• Nearly all are marine
• Radial symmetry

Front 32

• Gastrovascular cavity

Back 32

functions in digestion, circulation, and gas exchange, and as a hydrostatic skeleton

Front 33

What is the life cycle of cnidarians?

Back 33

with sessile polyp and motile medusa stages
Mature polyps produce medusae by asexual budding. Medusae reproduce sexually.
Ciliated larva (planula), settles to the bottom and develops into a polyp.

Front 34

Nematocysts

Back 34

specialized harpoon-like structures with toxins, used to capture large prey.

Front 35

Two groups of protosomes

Back 35

lophotrochozoans and ecdysozoans.
Derived traits:
• Anterior brain that surrounds entrance to digestive tract
• Ventral nervous system with paired or fused longitudinal nerve cords

Front 36

Protostome ancestor had a coelom, but it has been modified or lost in some groups.

Back 36

• Flatworms reverted to an acoelomate state.
• Some groups have a pseudocoel.
• Arthropods have a hemocoel, (“blood chamber”); fluid from an open circulatory system bathes the internal organs.
• Mollusks have an open circulatory system with vestiges of a closed coelom.

Front 37

Arrow worms:

Back 37

Small marine predators of planktonic protists and small fish.
Evolutionary relationships unclear.

Front 38

Lophotrochozoans:

Back 38

Have a lophophore, circular or U-shaped ring of ciliated, hollow tentacles around the mouth.
Used for food collection and gas exchange
Most are sessile as adults.

Front 39

How do trochophores move?

Back 39

larvae move by beating a band of cilia:

Front 40

Bryozoans

Back 40

Colonial animals that live in a “house” made of material secreted by the external body wall.
Individuals are connected by strands of tissue.
Colonies form by asexual reproduction; some can be huge.
In some species there is some specialization among colony members.

Front 41

Flatworms:

Back 41

Tapeworms and flukes are internal parasites, particularly of vertebrates.
• No digestive tract: they absorb digested food from gut of host
• Cause serious diseases such as schistosomiasis
• Have complex life cycles with multiple hosts
Turbellarians are free-living species

Front 42

What do flatworms lack and what must happen in order for them to live?

Back 42

no gas transport system, all cells must be near the surface—hence the dorsoventrally flattened body form.

Front 43

what is the digestive system of flatworms

Back 43

a many-branched blind sac. Provides large surface area for nutrient absorption.

Front 44

how do free-living species of flatworms move?

Back 44

glide over surfaces, powered by bands of cilia.

Front 45

Rotifers:

Back 45

Most are tiny, the size of protists.
• Complete digestive tract
• Pseudocoel functions as a hydrostatic skeleton
• A ciliated corona on the head sweeps food particles into mouth
Bdelloid rotifers are only known to have females

Front 46

Ribbon worms:

Back 46

• Complete digestive tract
• Rhynchocoel—fluid-filled cavity enclosing a hollow, muscular proboscis, the feeding organ.
The proboscis may extend much of the length of the body, and is everted for feeding. May be armed with stylets to pierce prey and inject paralytic toxins.

Front 47

Phoronids:

Back 47

Small, sessile marine worms that secrete tubes of chitin to live in.
Feed on suspended particles with a lophophore.

Front 48

Brachiopods:

Back 48

Solitary, with two-part shell—dorsal and ventral.
Lophophore is inside the shell.
Leave an excellent fossil record; were much more abundant during the Paleozoic and Mesozoic.

Front 49

Annelids:

Back 49

• Segmented body plan; body parts can move independently
• Each segment has a separate coelom and a nerve center (ganglion).
• Body covered by a thin, permeable body wall used for gas exchange; restricted to moist environments.

Front 50

Parappodia--annelid

Back 50

outgrowth on each segment

Front 51

what help annelids move?

Back 51

Stiff bristles (setae) on each parapodium aid in moving against the substrate.
Some species have tentacles to capture prey or filter food particles from the water.

Front 52

Pogonophorans-annelid

Back 52

have lost the digestive tract; they can absorb organic matter from the sediments.
Many have endosymbiotic bacteria that oxidize sulfur compounds, fixing carbon from methane in the process.
Uptake of O2, CH4, and H2S is facilitated by hemoglobin.
Live around hydrothermal vents in deep oceans

Front 53

oligochaetes-annelid

Back 53

no parapodia, eyes, or anterior tentacles.
Earthworms ingest soil to obtain nutrients.
All are hermaphroditic (both male and female).
Sperm are exchanged between two copulating individuals. Eggs and sperm are deposited outside the body, in a cocoon secreted by the clitellum. Fertilization occurs within the cocoon.

Front 54

leeches-annelid

Back 54

no parapodia or tentacles
Segments at ends of body are modified to form suckers, temporary anchors that help the leech move.
Feed by making an incision in the host and injecting an anticoagulant to keep blood flowing.
Medicinal leeches are still used to reduce fluid pressure, prevent blood clotting, and prevent scarring.

Front 55

Mollusks:

Back 55

The foot—a muscular structure originally used for locomotion and support for internal organs.
Heart, digestive, excretory, and reproductive organs are concentrated in a centralized, internal visceral mass.
The mantle—fold of tissue that covers organs of the visceral mass. Mantle secretes the calcareous shell.

Front 56

Where does gas exchange take place in a mollusk?

Back 56

Mantle extends beyond the visceral mass to form a mantle cavity containing the gills for gas exchange.
Some species use gills for filter feeding.
Some species have a radula to scrape algae from rocks.

Front 57

Chitons

Back 57

have 8 overlapping calcareous plates surrounded by the girdle.
Marine; scrape algae and other organisms from rocks with a radula.

Front 58

Gastropods

Back 58

Snails, whelks, limpets, slugs, nudibranchs (sea slugs), abalones
Include the only terrestrial mollusks—snails and slugs. The mantle tissue is modified into a lung.
Most species glide on the muscular foot, some use it for swimming.

Front 59

Bivalves

Back 59

: clams, oysters, scallops, mussels
Hinged, two-part shell
Some use the foot to burrow into sediment.
Feed by taking in water through an incurrent siphon, and filter food with their gills. Water and gametes exit through the excurrent siphon.
Gills are also used for gas exchange.

Front 60

Cephalopods

Back 60

squids, octopuses, nautiluses
Excurrent siphon is modified to eject water from mantle for “jet propulsion.”
Ability to move rapidly makes them efficient predators
Capture and subdue prey with tentacles
Head has complex sensory organs, notably eyes comparable to those of vertebrates

Front 61

What kind of shells did early cephalopods have?

Back 61

external chambered shells; nautiluses are the only surviving forms.

Front 62

What has happen to shells in mollusk groups over time?

Back 62

Shells have been lost several times in mollusk groups, including slugs and nudibranchs. Some are distasteful or toxic to predators and have bright colors for warning (aposematic coloration).

Front 63

Ecdysozoans

Back 63

have a stiff external covering, or cuticle, secreted by the epidermis.
To grow, the cuticle must be shed or molted, and replaced with a newer larger one.
Molting evolved more than 500 million years ago.
Genetic evidence, including a set of Hox genes shared by all ecdysozoans, suggests they have a single common ancestor.

Front 64

Some species of ecdysozoans have what kind of cuticles?

Back 64

thin cuticles, which allows exchange of gases, minerals, and water. They are restricted to moist environments

Others, especially the arthropods, have thick cuticles that function as exoskeletons.
They are thickened by layers of protein and the polysaccharide chitin.

Front 65

Arthropods

Back 65

have appendages manipulated by muscles.
Appendages are used for walking, swimming, gas exchange, food capture and manipulation, copulation, and sensory perception.
Chitin in the exoskeleton also prevents drying out—good for life on dry land.

Front 66

Nematodes (roundworms

Back 66

Unsegmented body; thick cuticle that provides shape
Gas and nutrient exchange occurs through the cuticle and the gut.
Probably the most abundant and universally distributed animal group.
Many are microscopic, but one species is 9 meters long.

Front 67

Horsehair worms:

Back 67

Unsegmented; very thin
Most live in freshwater in leaf litter and algal mats.
Larvae are internal parasites of crayfish and insects.
Adults have no mouth and reduced guts; feed only as larvae, absorbing nutrients from their hosts.

Front 68

Priapulids- small poorly known groups of marine ecdysozoans

Back 68

named for Greek fertility god

Front 69

Kinorhynchs
Small poorly known groups of marine ecdysozoans:

Back 69

very small, 13 segments

Front 70

Loriciferans
Small poorly known groups of marine ecdysozoans:

Back 70

not discovered until 1983, body covered by 6 plates

Front 71

what are arthropods?

Back 71

ecdysozoans with paired appendages.
Extremely diverse group, huge number of species and huge number of individuals.

Front 72

what is success of arthropods related to?

Back 72

Segmented bodies; each segment has muscles that operate that segment and the appendages attached to it. Allows complex movement and specialization of appendages.
Rigid exoskeleton provides support in water and on land, some protection from predators, and protection from drying out.

Front 73

Onychophorans (velvet worms):

Back 73

• May be similar to the arthropod ancestor
• Segmented; with fleshy, unjointed legs
• Thin, flexible cuticle with chitin
• Live in leaf litter in humid tropical habitats

Front 74

Tardigrades (water bears):

Back 74

Fleshy, unjointed legs
Very tiny, no circulatory or gas exchange systems.
Some species live on water films on plants. When the water dries, they shrink and enter a dormant state that can last at least 10 years.

Front 75

Chelicerates:

Back 75

Two pairs of appendages modified into mouthparts, called chelicerae; used to grasp prey

Front 76

Pycnogonids (sea spiders

Back 76

most are small marine predators
Horseshoe crabs—four living species

Front 77

Arachnids

Back 77

: spiders, scorpions, harvestmen, mites, ticks
Simple life cycle; miniature adults hatch from internally fertilized eggs and begin independent lives almost immediately.
Some mites and ticks are parasites of animals, and vectors of diseases.
Spiders are important terrestrial predators; hollow chelicerae are used to inject venom into prey.

Front 78

Myriapods

Back 78

centipedes, millipedes
• Have mandibles for chewing and biting as well as grasping prey.
• Segmented trunks with many pairs of legs
Centipedes—one pair of legs per segment; prey on insects and other small animals.
Millipedes—two pairs of legs per segment; scavenge and eat plants.

Front 79

Crustaceans

Back 79

Decapods: shrimps, lobsters, crayfishes, crabs
Isopods, amphipods, ostracods, copepods branchiopods, and barnacles
Appendages on different parts of the body are specialized for different functions—gas exchange, chewing, capturing food, sensing, walking, swimming.

Front 80

Crustaceans

Back 80

Decapods: shrimps, lobsters, crayfishes, crabs
Isopods, amphipods, ostracods, copepods branchiopods, and barnacles
Appendages on different parts of the body are specialized for different functions—gas exchange, chewing, capturing food, sensing, walking, swimming.

Front 81

Hexapods

Back 81

: insects and their relatives; millions of species
Abundant and diverse in terrestrial and freshwater environments; only a few live in salt water.
Wingless relatives: springtails, bristletails, proturans; probably similar to insect ancestors. Have internal mouthparts.

Front 82

what are the three regions of insects?

Back 82

head, thorax, and abdomen.
One pair of antennae on head; 3 pairs of legs attached to the thorax.
In most groups the thorax also bears 2 pairs of wings.
External mouthparts
Gas exchange system of air sacs and channels (tracheae) that extend from external openings called spiracles.

Front 83

Pterygote (winged) insects

Back 83

2 pairs of wings, one or both pairs have been lost in some groups.

Front 84

Metamorphosis

Back 84

substantial morphological changes between developmental stages
Incomplete metamorphosis—changes are gradual

Front 85

Complete metamorphosis

Back 85

changes are dramatic; different life stages may be specialized for different environments and food types.

Front 86

What were the first flying animals?

Back 86

Pterygote insects were the first flying animals.
Flight opened up new lifestyle and feeding opportunities—one reason for success of insects.

Front 87

When did insects begin to diversify?

Back 87

Insects began to diversify when land plants appeared. They evolved in an environment that lacked similar organisms, another reason for success.

Front 88

What controls development of insect wings and crustacean appendages?

Back 88

Homologous genes control development of insect wings and crustacean appendages; suggests that insect wings evolved from a crustacean-like limb:

Front 89

Neopterans

Back 89

insects that can tuck their wings out of the way upon landing.

Front 90

Deuterostomes:

Back 90

• Triploblastic and coelomate
• Internal skeletons
• Includes many large animals—including humans
• Complex behaviors are especially well developed in some groups

Front 91

Deuterostomes:

Back 91

• Triploblastic and coelomate
• Internal skeletons
• Includes many large animals—including humans
• Complex behaviors are especially well developed in some groups

Front 92

Echinoderms:

Back 92

sea stars, sea urchins, sea cucumbers, crinoids
Only 6 of 23 fossil groups survive today.
Nearly all marine
Change from a bilaterally symmetrical larva to an adult with pentaradial symmetry.
Adults have no head, and move equally well in many directions.

Front 93

Echinoderms have what?

Back 93

oral side (with the mouth) and an opposite aboral side (with the anus).
A system of calcified internal plates fuse to form an internal skeleton.
The water vascular system is a network of water-filled canals leading to extensions called tube feet; functions in gas exchange, locomotion, and feeding.

Front 94

Crinoids (sea lilies and feather stars),

Back 94

were more abundant and species-rich 300 to 500 million years a
Most are sessile; attached to substrate by a stalk.

Front 95

Tube feet have been modified in different ways to capture prey

Back 95

Sea lilies—tube feet are covered with sticky mucus to catch food particles from water.
Sea cucumbers have anterior tube feet modified into sticky tentacles that are protruded from the mouth.
Most brittle stars ingest particles from the sediments and digest the organic matter.

Front 96

Hemichordates (acorn worms and pterobranchs) have three body parts:

Back 96

• Proboscis
• Collar
• Trunk

Front 97

Acorn worms

Back 97

• can be up to 2 meters long; live in burrows in marine sediments.
• breathe by pumping water into mouth and out the pharyngeal slits where gas exchange occurs.
• capture prey with proboscis, which is coated with sticky mucus.

Front 98

Pterobranchs:

Back 98

• small, only 12 mm long
• live in tubes secreted by the proboscis.
Some are solitary and some colonial.
The collar has one to nine pairs of arms with tentacles that capture prey and function in gas exchange.

Front 99

when are evolutionary relationships most evident?

Back 99

in the early developmental stages.

Front 100

three chordate clades

Back 100

• Cephalochordates
• Urochordates
• Vertebrates

Front 101

All chordates have what three derived structures?

Back 101

• Dorsal hollow nerve cord
• Tail that extends beyond the anus
• Dorsal supporting rod called the notochord

Front 102

Notochord

Back 102

has a core of large cells with fluid-filled vacuoles, making it rigid but flexible.
In urochordates it is lost in metamorphosis to the adult stage.
In vertebrates it is replaced by vertebrae.

Front 103

Ancestral pharyngeal slits in chordates

Back 103

are present at some developmental stage; often lost as adults.
The pharynx develops around the pharyngeal slits.
In chordate ancestors it functioned in gas exchange. It is enlarged in some chordates and lost in others.

Front 104

Cephalochordates (lancelets):

Back 104

• Small; 5 cm long
• Notochord persists throughout life
• Live in shallow marine and brackish waters
• Lie covered in sand with head protruding, and filter prey from the water with the pharyngeal basket.

Front 105

Urochordates
ascidians (sea squirts):

Back 105

• Adults are sessile; some form colonies by asexual budding; colonies can be meters across.
• Adult body is enclosed in a tough tunic (alter name is “tunicates”)
• Filter prey with pharyngeal basket

Front 106

what do urochordate larvae do when developing?

Back 106

Urochordate larvae swim in the plankton for a short time, then settle and transform into adults.
The tadpolelike larvae shows the relationship between ascidians and vertebrates.

Front 107

Vertebrates

Back 107

The jointed, dorsal vertebral column replaces the notochord during early development.
Probably evolved in the oceans and have since radiated into marine, freshwater, terrestrial, and aerial environments.

Front 108

what are thought to be sister group of all other vertebrates?

Back 108

hagfishes
They have three small hearts, a partial cranium, no stomach, no jaws, skeleton is cartilage; no vertebrae.
Gene sequences suggest hagfishes may be more closely related to lampreys, and secondarily lost many vertebrate features.

Front 109

what sense do hagfishes lack and what do they do to combat this?

Back 109

are blind and produce large amounts of slime as a defense.
They have no jaws but have a specialized structure to capture prey and tear up dead organisms.
Development is direct; adults can change sex from year to year.

Front 110

lampreys

Back 110

have a complete cranium and cartilaginous vertebrae.
Development is complete metamorphosis from filter-feeding larvae (ammocoetes), which are similar to lancelets.
Adults of many species are parasitic; the round mouth is used for attaching to fish and rasping at the flesh.
Some adults are nonfeeding.

Front 111

what are the four key features of vertebrates?

Back 111

• Anterior skull with a large brain
• Rigid internal skeleton supported by the vertebral column
• Internal organs suspended in a coelom
• Well-developed circulatory system with a ventral heart

Front 112

when and from what did jawed fished evolve?

Back 112

in the Devonian period.
Jaws evolved from the skeletal arches that supported the gills.
Jaws and teeth improved feeding efficiency and prey capture.

Front 113

Chondrichthyans

Back 113

sharks, skates, rays, chimaeras
Skeleton of pliable cartilage; leathery skin
Most sharks are predators.
Skates and rays live on the ocean floor and feed on animals buried in the sediments

Front 114

Ray-finned fishes

Back 114

• Internal skeletons of calcified, rigid bone
• Body covered with scales
• Gills open into a chamber covered by a flap, (operculum). Movement of the operculum improves water flow over the gills.
Radiated extensively in the Tertiary; exploit nearly all types of aquatic food sources

Front 115

what evolution set stage for evolution of land animals?

Back 115

Evolution of lunglike sacs set stage for evolution of land animals.
Changes in fin structure allowed some fish to support themselves in shallow water and later move onto land

Front 116

Sarcopterygians

Back 116

coelacanths, lungfishes, tetrapods
Jointed appendages joined to the body by a single enlarged bone.
Coelocanths were thought to have become extinct 65 mya, but living ones were found off South Africa in 1938.
They have a cartilaginous skeleton that is a derived feature.

Front 117

Lungfishes

Back 117

• Six surviving species in tropical swamps
• Have lungs and gills
• Burrow in mud when ponds dry up, and survive many months in an inactive state while breathing air.

Front 118

what did some sarcopterygians evolve into?

Back 118

tetrapods—four-legged vertebrates.
Earliest tetrapod limbs may have held animals upright in shallow water, allowing head to be above water.
The limbs were then co-opted for movement on land.

Front 119

Amphibians:

Back 119

caecilians, frogs and toads (anurans), salamanders
Most live in moist environments—they lose water easily through the skin, and eggs dry out if exposed to air.
Some species are entirely aquatic. In others, adults live on dry land but must return to water to lay eggs; larvae develop in the water.

Front 120

Anurans:

Back 120

• Some have tough skins and other adaptations to live in dry habitats.
• Many are arboreal; some are completely aquatic.
• All have a pelvic region modified for hopping or kicking in the water.

Front 121

Salamanders:

Back 121

Many live in moist soil and rotting logs.
One group has lost lungs and relies on gas exchange through skin and mouth lining.
Completely aquatic species have evolved several times through paedomorphosis (retention of juvenile characteristics).

Front 122

Factors on why amphibian species are declining

Back 122

Several factors may be implicated:
• Habitat destruction
• Increased UV radiation due to ozone layer thinning
• Air pollution
• Agricultural pesticide pollution
• Pathogenic chytrid fungus.

Front 123

Amniotes
Many adaptations led to success on land:

Back 123

• Amniote eggs
• Tough skin with scales and other modifications to prevent drying.
• Excretory organs that allow excretion of concentrated urine; allows excretion of nitrogen wastes without losing a lot of water.

Front 124

Amniote eggs

Back 124

• Impermeable to water;
• Leathery or calcium-impregnated shells prevent water loss but allow gas exchange;
• Store food for the embryo in the form of yolk
Extraembryonic membranes protect embryo from desiccation; assist gas exchange and nitrogen excretion

Front 125

what are reptiles diverged from?

Back 125

amniotes

Front 126

Turtles have changed very little over the millennia.

Back 126

• Dorsal shell is an expansion of the ribs.
• Most are aquatic, a few are terrestrial.
• Sea turtles come ashore only to lay eggs. Human exploitation has resulted in declining populations—all are now endangered.

Front 127

Lepidosaurs:

Back 127

Squamates—lizards, snakes, and amphisbaenians
Tuataras—resemble lizards; only two species survive
Skin with horny scales reduces water losses; gas exchange is through lungs; three-chambered heart.

Front 128

What are most lizards?

Back 128

Most lizards are insectivores, some herbivores, some predators.
Largest lizard is the Komodo dragon of the East Indies.
Snakes are limbless squamates, and all are carnivorous. Many have evolved venom glands.

Front 129

Archosaurs:

Back 129

: crocodilians, dinosaurs, and birds.Dinosaurs dominated terrestrial environments for 150 million years.
During the Mesozoic, most large animals were dinosaurs.
Only the birds survived the mass extinction at the end of the Cretaceous

Front 130

archosaurs: crocodilians

Back 130

crocodiles, caimans, gharials, alligators
• Live in tropical and warm temperate environments.
• They build their nest on land or floating piles of vegetation. Heat from decaying organic matter warms the eggs.
• All are carnivorous.

Front 131

What did bird probably arise from

Back 131

theropod dinosaurs, which had many characteristics of birds:
Bipedal, hollow bones, a furcula (wishbone), three-fingered feet and hands, and a pelvis that points backwards.
Scales of some theropods were modified into feathers.

Front 132

what is the oldest known fossil bird?

Back 132

Archaeopteryx is the oldest known fossil bird (150 million years).
Had teeth, feathers, well-developed wings
Clawed fingers on its forelimbs probably assisted it in clambering over tree branches.

Front 133

What was a major source of diversification in birds?

Back 133

Evolution of feathers was a major force for diversification.
Feathers are lightweight but strong; provide flying surfaces and insulation.
Bones of theropods are hollow with internal struts—lightweight but strong. The sternum forms a large, vertical keel to which flight muscles are attached.

Front 134

Is fligh metabolically expensive?

Back 134

High metabolic rates generate a lot of heat.
Birds control body heat by holding feathers close to the body or elevating them.
Bird lungs allow air to flow through in one direction, instead of pumping air in and out. Increased gas exchange efficiency supports high metabolic rates

Front 135

Mammals

Back 135

Coexisted with dinosaurs for millions of years.
After extinction of nonavian dinosaurs, mammals diversified and grew larger.
The blue whale is the largest animal on Earth, up to 33 meters long.

Front 136

what are the key features of mammals?

Back 136

• Sweat glands
• Mammary glands
• Hair
• Four-chambered heart that completely separates oxygenated from deoxygenated blood
• Eggs are fertilized, and embryos start development, within the female body.

Front 137

Prototherians:

Back 137

duck-billed platypus, echidnas
Only in Australia and New Guinea.
Lack a placenta, lay eggs, and have sprawling legs

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Therians:

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: all other mammals; includes marsupials and eutherians
Marsupials carry and feed young in a ventral pouch. Young are born early and crawl into pouch for further development.

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Eutherians:

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20 major groups
• Rodents: teeth adapted for gnawing; largest group
• Bats: flying mammals
• Moles and shrews: 3rd largest group

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What helped transform terrestrial landscape?

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Grazing and browsing helped transform terrestrial landscapes.
Large size evolved in several groups of grazing and browsing mammals.
Herbivory favored evolution of the spines, tough leaves, and difficult-to-eat growth forms found in many plants.
Herbivores also adapted—coevolution.

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What eutherian lineages returned to aquatic habitats?

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whales, dolphins, seals, etc.
Cetaceans evolved from artiodactyl ancestors (whales are related to the hippopotamuses).
Limbs became modified as flippers.
Others retain their limbs but live in both fresh and salt water (e.g., sea otters).

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Primates

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Prosimians (lemurs, lorises), restricted to Africa, Madagascar, sand tropical Asia.
Anthropoids (tarsiers, Old World monkeys, New World monkeys, apes)

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All new world monkeys are?

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are arboreal, many have prehensile tails.

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Some old world monkeys are...?

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arboreal, others are terrestrial; none have prehensile tails.

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What are modern decendents from the seperation of old world monkeys and app lineage?

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Asian apes (gibbons and orangutans), African apes (gorillas and chimpanzees), and humans are their modern descendants.

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What modern descendent lead to chimpanzees and the hominid clade?

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About 6 mya in Africa, a lineage split occurred that would lead to the chimpanzees and the hominid clade.
Earliest known hominids, ardipithecines, were bipedal.
With bipal locomotion, forelimbs are free to manipulate and carry objects; eyes are elevated to look for prey; locomotion is more energetically economical.

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Australopithecines

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descended from ardipithecines.
The most complete skeleton found to date is “Lucy” (Australopithecus afarensis), in Ethiopia; about 3.5 million years old.

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What lineage gave rise to the genus homo?

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australopithecines

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Homo lineage

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brain size increased while jaw muscles decreased in size.
Larger brain size was probably favored by increasingly complex social life; features that increased communication between individuals would have been favored.

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What is a shared derived trait or synapomorphy of the plantae?

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primary endosymbiosis

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What were the first clades to branch off after primary endosymbiosis?

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common name: algae

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What was the ancestor of plantae similar to?

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glaucophytes

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Red algae

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multicellular; have phycoerythrin and other pigments.
Most are marine and the ratio of phycoerythrin to chlorophyll a depends on light intensity or water depth.
> phycoerythrin deeper water
> chlorophyll a shallow water

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Other algae group in plantae are called green algae and have three clades

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Chlorophytes
Coleochaetophytes
Charophytes

Have chlorophyll a and b; store energy as starch

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Key synapomorphy of land plants...

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is an embryo that is protected by tissues of the parent plant.
They are also called embryophytes.

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Vascular plants (tracheophytes

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well developed vascular systems with tracheids.

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Non-vascular plants

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some have conduction cells, but no tracheids. Not a clade.

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What green algae groups are the closet relatives of land plants?

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coleochaetophytes and charaphytes

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charophytes are thought to be the sister group of what?

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land plants, based on DNA sequences and several synapomorphies:
Plasmodesmata join adjacent cells
Branching, apical growth
Similar peroxisomes, mitosis and cytokinesis, and chloroplast structure

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Stomata

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closable openings that regulate gas exchange

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Cuticle

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a waxy coating that slows water loss

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Gametangia,

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organs that enclose gametes and prevent them from drying out

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Embryos

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young plants contained within a protective structure

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land plants have alternation of generations

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Includes a multicellular diploid stage and a multicellular haploid stage.
Gametes are produced by mitosis, spores are produced by meiosis.
Spores develop into multicellular haploid organisms.

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Sporophyte

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the multicellular diploid plant
Cells in the sporangia produce haploid spores by meiosis.

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spores develop into what?

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gametophyte, the multicellular haploid plant.

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what does gametophyte produce?

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Gametophyte produces haploid gametes by mitosis.
Fusion of gametes produces a diploid zygote, which developed into the sporophyte.

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Nonvascular plants

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liverworts, mosses, hornworts
Live in moist habitats; have thin cuticles
Mostly small; they have no vascular system to transport water, so size is restricted.
Small enough that minerals can be distributed throughout their bodies by diffusion

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Liverworts

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Green, leaflike gametophytes
Sporophyte remains attached to the larger gametophyte.

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Mosses

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Have stomata
Have cells called hydroids, which die and leave a channel through which water can move.

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Hornworts

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Sporophytes look like small horns.
Cells contain one chloroplast.
Have a symbiotic relationships with cyanobacteria that live in internal cavities and fix nitrogen.
Examples of all three can be seen in Figure 21.5

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gametophyte/sporophyte relationship in nonvascular plants

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gametophyte is photosynthetic.
The sporophyte is nutritionally dependent on the gametophyte and remains attached to it.
Gametes are produced in the antheridium and archegonium. The sperm must swim or be splashed by water to reach the egg.

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tracheid

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evolved in sporophytes and was critical for evolution of land plants.
Tracheids allow transport of water and materials.
Lignin in the cell walls provides structural support, allowing taller growth.

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vascular system

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consists of tissues specialized for transport of water and materials from one part of the plant to another.
Evolution of vascular tissue allowed land plants to spread to new environments and diversify rapidly.
Xylem conducts water and minerals from the soil to aerial parts of the plant.
Phloem conducts products of photosynthesis from production sites to use or storage sites

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Rhyniophytes

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earliest vascular plants
No roots; were anchored in soil by rhizomes (like ferns today)
Dichotomous branching pattern

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Lycophytes

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club mosses
True branching roots
Have leaflike structures (microphylls), arranged spirally on the stem
Dichotomous branching
Sporangia in club-like clusters called strobili

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Monilophytes

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horsetails and ferns: a clade
A synapomorphy: leaf gaps in stem where leaves emerge.
Also have differentiation between main stem and side branches

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Horsetails

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all in genus Equisetum
Reduced true leaves in whorls
True roots
Independent sporophyte and gametophyte
Only about 15 species remain living all in the genus Equisetum

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Leptosporangiate ferns:

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Sporangia walls only one cell thick
Most are terrestrial; a few aquatic species
Require liquid water for movement of sperm, so most inhabit moist woodlands and swamps
Gametophyte is small and short-lived; sporophyte can be very large and can sometimes survive for hundreds of years.
Sporangia are borne on a stalk in clusters called sori, on the undersurfaces of the leaves.

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Euphyllophytes

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clade consisting of monilophytes and seed plants

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Overtopping growth

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one branch differentiates from and grows beyond the others; an advantage in competition for light

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Megaphylls

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more complex leaf; may have arisen from flattening of a branch tip.

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what are most vascular plants?

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heterosporus

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megaspore

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develops into a female gametophyte (megagametophyte) that produces only eggs

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microspores

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develop into a male gametophytes (microgametophytes) that produce only sperm.

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Seed plants (gymnosperms and angiosperms):

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Seeds provide a secure and lasting dormant stage for the embryo.
Seeds can be dormant for many years, even centuries.

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Trend in plant evolution

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The sporophyte became less dependent on the gametophyte; the gametophyte became smaller.
The male gametophyte is a pollen grain—the female megagametophyte is held in the integument, together they form the ovule.
Pollination—promotes pollen tube growth toward the megagametophyte where fertilization occurs.
The diploid zygote divides to form an embryonic sporophyte, then enters a dormant stage as a multicellular seed.

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what is one reason for the evolutionary success of seed plants?

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seeds

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Secondary growth

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growth—increasing diameter of roots and stems by growth of xylem—forms wood.
Older wood becomes clogged with resins but provides support and allows plants to grow to great heights.
Many plant groups have lost the woody growth habit.

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Gymnosperms

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seed plants that do not form flowers or fruits.
Ovules and seeds are not protected by ovary or fruit tissue.
Have only tracheids as the water-conducting and support cells within the xylem.

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Four groups of gymnosperms

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cycads, gingkos, gnetophytes, conifers

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Cycads

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tropical, earliest diverging clade

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Gingkos

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common in Mesozoic, today only one species: Gingko biloba

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Gnetophytes,

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some characteristics similar to angiosperms; Welwitschia

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Conifers

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cone-bearing plants

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cones of conifers

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Cones contain the reproductive structures.
Megastrobilus—female cone, seeds protected by woody scales
Microstrobilus—male pollen-bearing cone

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Synapomorphies of the angiosperms

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Double fertilization
Nutritive tissue called the endosperm
Ovules and seeds enclosed in a carpel
Germination of pollen on a stigma
Flowers
Fruits
Phloem with companion cells
Reduced gametophytes

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Inflorescence

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group of flowers; types are characteristic of plant families.

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Petals (collectively, the corolla) and sepals

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(collectively, the calyx) can be important in attracting pollinators

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Stamens

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bear the male microsporangia

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where are ovules and seed enclosed

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modified leaf called a carpel.

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what does pistal do?

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or more fused carpels, containing the ovaries.

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Perfect flowers

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have both megasporangia and microsporangia.

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Imperfect

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two flower types, male and female

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Monoecious

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male and female flowers occur on the same plant.

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Dioecious

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male and female flowers are produced on different plants

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what is a problem in perfect flowers?

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self-pollination, have elaborate mechanisms to prevent self-pollination

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What helps angiosperms pollinate?

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pollinated by animals and they have coevolved.
Many pollination mutualisms are vital to both parties. Some are highly specific—only one insect species pollinates one plant species.
Flower structure has diversified under the selective pressure of pollinators.
Flowers often provide food for pollinators—nectar and pollen; and have specialized structures or colors to attract them.

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where do fruits develop in angiosperms?

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Fruits develop from the ovaries after fertilization.
Fruits protect seeds and aid in dispersal.
Some are eaten by animals or become attached to animals for dispersal.

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Angiosperm clades

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Recent evidence suggests that the sister clade for the remaining angiosperms is a single species of Amborella.
The two largest clades:
Monocots (1 cotyledon)
Eudicots (2 cotyledons)
Magnoliids are the sister group to the monocots and eudicots.