Animal diversity questions Flashcards
1
Q
What is a “metazoan”?
A
means animal or (later/ after animal)
2
Q
What are the defining characteristics of animals?
A
Eukaryotic
Multicellular-except gametes (sperm and egg)
heterotrophic
All individuals are diploid; Only gametes are haploid
No cell walls(use extracellular structural proteins instead
in particular collagen, the most abundant protein in your body, 1/3 of all your protein)
ingest their food then digest
3
Q
Compare digestion of animals and fungi
Are fungi more closely related to animals or plants?
A
Both are heterotrophs
Animals ingest food bring in and then digest using enzymes
Fungi (digest food externally and take in after)
are more closely related to animals than plants have cell walls
4
Q
How do plants obtain nutrition?
A
autotrophic eukaryotes- capable of making their own food- thru photosynthesis
5
Q
What is the Haploid stage?
A
composed of gametes (egg and sperm) that are produced by meiotic division by the diploid stage
Cells of haploid stage don’t undergo further division
6
Q
How does reproduction and development start?
A
The sperm fertilizes the egg forming a diploid zygote
7
Q
Describe the animals developmental cycle
A
- The zygote of an animal undergoes mitotic cell division called cleavage
- An eight cell embryo is formed by 3 rounds of cell division
- Cleavage produces a multicellular stage called a blastula
- Most animals undergoes gastrulation
- The pouch formed by gastrulation called the archenteron opens to the outside via the blastopore
- The endoderm of the archenteron develops into the tissue lining the animals digestive tract
8
Q
List the evidence of shared ancestry between the animals and choanoflagellates
A
- Choanocyte cells of sponges look like choanoflagellates showing that the molecular evidence is true that animals evolved from choanoflagellate like animals
- collar cells that are similar have been found in echinoderms flatworms and cnidarians but not in non choanoflagellate animals
- DNA evidence that shows that animals and choanoflagellate are sister groups and signaling and adhesion proteins which had been only found in animals were found in them too
9
Q
What are the characteristics of radial symmetrical animals? give examples
A
Animals are sessile(living attached to a substrate )or platonic
(drifting or weakly swimming such as jellyfish)
Diploblasts are this
Don’t have distinct head region
ex; cnidarians, some anemones
10
Q
What are the characteristics of bilaterally symmetrical animals? give examples
A
ex; lobster, mammals arthropods
Has 2 axes of orientation: front to back and top to bottom
Have sensory equipment at anterior end including the nervous system (brain)- called cephalization
More active than radial animals(The central nervous system allows them to coordinate complex movements involved in crawling burrowing flying or swimming )
Triploblastic
11
Q
What animals lack tissues?
A
sponges have no tissues meaning they have no organs and are asymmetrical
(monophyletic)
12
Q
What is the function of the Body Cavities of triploblasts?
A
Structural support
Formation of the internal transport system to supply nutrients
Allow efficient gas exchange
Remove waste
13
Q
Why is the Hemocoel called a false body cavity?
A
because there isn’t mesoderm surrounding it completely
14
Q
What is the function of heomocoel body cavity and fluid ?
A
Internal circulation
Nutrient transport
Waste removal
Hydrostatic skeleton
15
Q
What kind of cleavage do Protostomes go through? Deuterstomes?
A
P- spiral and determinate
d- radial and indeterminate
16
Q
Compare coelom formation in deuterostomes and protostomes?
A
Protostomes–the solid masses of mesoderm cells split and form the coelom (coelom opens up inside middle of mesoderm)
Deuterostome development the mesoderm buds from the wall of the archenteron and its cavity becomes the coelom (folds in from mesoderm up at the top of archenteron)
17
Q
Compare the fate of the blastopore in deuterostomes and protostomes
A
In protostome development the mouth forms from the blastopore
Deuterostome development- the mouth forms from a secondary opening the blastopore forms the anus
18
Q
What are sponges considered? why
A
basal animals
- their lack of body symmetry
- the close resemblance of poriferan cells to slime molds
- their lack of germ layers
- the close resemblance of choanocytes to choanoflagellates
19
Q
What is the most diverse clade
A
Bilateria
Bilateral symmetry and 3 germ layers
20
Q
What are are 3 major clades of bilaterian animals ?
A
Deuterostomia
Lophotrochoza
Ecdysozoa
21
Q
How can animals be categorized?
A
Animals can be categorized by a number of features:(through morphology) Presence of tissues Body symmetry Body segmentation Presence of exoskeleton Embryonic tissue layers Digestive openings Mouth first Presence of body cavity
22
Q
Which came first, the sponge or the comb jelly?
A
Sponges did come first Ctenophores: are not a basal animal come between sponges and cnidarians Not always radial Have more cell types than sponges Have a rudimentary nervous system(more complicated than sponges) Similar to cnidarians nervous system Active hunters Called comb jellies- have combs of cilia
23
Q
What are the defining characteristics of phylum porifera?
A
High resemblance to certain colonial protists( cellular slime molds)
are sedentary
asymmetric body plan
Are suspension feeders-(have spongocoel and osculum)
Lack tissue but contain many cell types (choanocytes and amebocytes)
body consists of 2 layers of cells
sequentially hermaphroditic
No nervous system( have individual cells that contain much of the machinery of typical animal nerve cells (lot of proteins DNA sequences)
Adults are sessile(permanently attached to something)- larve swim
24
Q
What do amebocytes do?
A
Move through the mesohyl
Take up food from surrounding water and from choanocytes digest it and carry nutrients to other cells
Manufacture tough skeletal fibers within the mesohyl
Some fibers are sharp spicules made of calcium carbonate or silica(the exoskeleton) Or flexible protein called spongin
Are totipotent
25
What does it mean to be totipotent?
characteristic of amebocytes
| can transfer into any cell type as needed
26
What do Choanocytes do?
Pull water in thru the pores
Look similar to choanoflagellates (pre animals single cellular)- support molecular evidence that animals evolved from choanoflagellate like ancestors
Engulf bacteria by phagocytosis
27
What are the defining characteristics of phylum cnidaria?
The first eumetazoans
only two tissue layers
Most are marine; a few are in fresh water
Only one digestive system opening
diploblastic
radial body plan
gastrovascular cavity(single opening to this cavity functions both as mouth and anus )
Body wall has 2 layers of cells( gastrodermis and epidermis)
2 variations in body plan( polyp or medusa)
28
Polyps
Ex: hydra and sea anemones
Primary sedentary- but can move
When threatened by a predator some can swim by bending their body column back and forth
29
Medusa
Moves freely- free swimming jellies
Some exist only as one body plan some have both stages in their life cycle
Are predators that use tentacles arranged in a ring around their mouth to capture prey and push the food into the gastrovascular cavity
Tentacles are armed with batteries of cnidocytes
30
Medusa
Moves freely- free swimming jellies
Some exist only as one body plan some have both stages in their life cycle
Are predators that use tentacles arranged in a ring around their mouth to capture prey and push the food into the gastrovascular cavity
Tentacles are armed with batteries of cnidocytes
Contain cnidae
31
What are Medusozoans?
clade of cnidarians (monophyletic)
All cnidarians that produce a medusa are members of this clade
Include jellies box jellies and hydrozoans
Alternate between polyp and medusa life cycle
32
What are Anthozoans?
clade of cnidarians (monophyletic)
ex; Sea anemones and coral
only occur as polyps
have Exoskeleton
Corals make skeleton of calcium carbonate
Coral reefs are hard external skeletons secreted by certain cnidarians
33
What are Hydra ?
Freshwater cnidarians
Immortal
Exist only in polyp form but are not sessile- they “walk”
Only a few cell types
Frankenhydra- if you cut 2 they can fuse
Don’t have a mouth- rip body apart to swallow
34
Which is the biggest subphyla?
Lophotrochozoans phyla contains most pyhla)
35
Lophotrochozoans phyla include?
```
Flatworms
Rotifers
Ectoprocts
Brachiopods
Molluscs
Annelids
```
36
Flatworms(platyhelminthes)
Live in marine or freshwater
Have thin bodies that are flattened dorsoventrally
First animals with bilateral symmetry
First animals with 3 embryonic tissue layers
Are protostomes
Undergo triploblastic development- but lack a body cavity
have gastrovascular cavity
Only one digestive opening
Have no organs specialized for gas exchange
Protonephridia
lack circulatory system
True nervous system
37
describe the Flatworms(platyhelminthes) nervous system?
```
Paired eyespots
Paired anterior ganglia (close to being a brain)
Segmented gangia
Paired ventral nerve cords
Transverse nerve cords
```
38
What are examples of platyhelminthes?
Include tapeworms and flukes
39
What are the benefits of the flat shape of flatworms?
Flat shape places all cells close to water or in their gut
| Flat shape maximizes surface area for efficient exchange processes
40
Where are the nerve cords located on Invertebrates ?
have nerve cords always on ventral side
41
What are the defining characteristics of Planarians?
type of free living flatworm
Found in freshwater ponds
Move by using cilia on their ventral surface
Nervous system is more complex than cnidarians
Some can reproduce asexually through fission
Sexual reproduction can also occur
Are hermaphrodites
Exhibit extraordinary regenerative ability
important in the study of regenerative medicine
42
Tapeworms
Adults live mostly in vertebrates
Lack a mouth and gastrovascular cavity(no real digestive system)- absorb nutrients released by digestion in the hosts intestine
43
Lophotrochozoan named?
Lophophore- a crown of ciliated tentacles that function in feeding
Trochophore larvae- distinctive larvae stage observed in some Lophotrochozoan including some annelids and molluscs
44
What examples of molluscs?
Ex: snails slug oysters clams octopuses
45
what is the Second most diverse phlyum of animals ?
molluscs
46
What are the defining characteristics of molluscs?
Bilateral
triploblastic
protostomes
Complete digestive tract (2 digestive openings) (aka alimentary canal or gastrointestinal tract)
Are soft bodied and secrete a hard protective shell made of calcium carbonate
All have a similar body plan : foot visceral mass and mantle
Open circulatory system (except cephalopods)
Complete nervous system(brains, eyes
Paired ventral nerve cords from brain that go the entire length of the body
Some simpler animals have ganglia that encompasses esophagus(invertebrates)
Shell is not shed does not moult unlike ecdyszoans
They grow by secreting more shell
47
What is the benefit of a complete digestive tract?
Benefit is that there is one directional digestive tract with specialized regions(multiple things can happen at once)
48
What are the groups of molluscs?
Chitons
Gastropods (belly foot)
Bivalves (2 doors)
Cephalopods (head foot)
49
Gastropods
ex- Snails and slugs
Have a mucus gland and animals slides along it
¾ belong to this clade
marine freshwater or terrestrial species
Move very slowly by cilia or foot
Have single spiraled shell into which the animal can retreat when threatened
50
Bivalves
Are all aquatic
Ex- clams(sedentary) oysters mussels(sessile) scallops (swim and have eyes)
Have a shell divided into 2 halves which are hinged and have powerful adductor muscles drawing them in tightly to protect animals soft body
Have no distinct head and no radula
Have eye and sensory tentacles along the outer edge of the mantle
Mantle cavity of bivalve contains gills that are used for gas exchange as well as feeding
Most are suspension feeders
51
Cephalopods
Ex: nautiluses cuttlefish squids and octopuses
Are active marine predators
only molluscs with a closed circulatory system
Most advanced and largest eyes
Ammonites
Well developed brain and sense organs
Octopus and squids have no shell (have huge brains)
Don’t have a mantle either
52
What are the defining characteristics of Annelids
```
Segmented worms
Bilateral
triploblastic
protostome
Complete digestive tract with 2 openings
Digestive systems not segmented specialized along the path (elongates as animal develops)
Nervous and closed circulatory systems are segmented
2 groups: Errentia and Sedentaria
```
53
Why is segmentation good?
Makes development easy because segments just repeat (with some modifications)
54
How are different segments made?
Hox genes
- determine when and where things grow
Determine where the brain will go intestines etc (where changes in segments grow)
55
How does segmented body plan in annelids work?
During development segments just repeat (with some modifications)
Makes development easy
Most tissue are the same in each segment (segmental vessels excretory organs)
Each segment is separated by each other by septum
56
Clade Errantia
Mostly marine with gills
Many are mobile
Many are predators
Have well developed jaws and sensory organs
57
Clade Sedentarians
Earthworms, leeches (both blood sucking and predator types tube dwelling worms
Tend to be less mobile
58
Which clade has the most species?
Ecdysoza
59
Which clade has the most species?
Ecdysoza
60
What are the 2 largest phyla of Ecdysozoa?
Nematode's, arthropods
61
What are the defining characteristics of Nematodes(roundworms) ?
Bilateral
triploblastic
protostomes (complete digestive tract, 2 openings)
Found in most aquatic habitats, in the soil
Many are parasites
Don’t have segmented bodies
Covered by tough cuticle(exoskeleton)
Have an alimentary canal- lack circulatory system
Nutrients are transported throughout the body via fluid in the hemocoel
Body wall muscles are longitudinal
62
Which nematodes arent parasites?
Caenorhabditis elegans
Benign little things (abt 1 mm)
Enormously important in developmental biology genetics neuroscience
Genetic model species (sequenced editable genome)
Every cell is mapped
Hermaphrodites; 959 total cells 302 nerve cells
Male have 1031 total cells 385 nerve cells
63
What are the defining characteristics of Arthropods?
Phylum with the most species(extremely diverse)
Molting exoskeleton
Segmented body plan
Segments fuse to form major body parts (distinct head, thorax and abdomen (post genital region) )
jointed appendages(legs and antennae)
Have well developed sensory organs including eyes, olfactory receptors and antennae
Some undergo metamorphosis
64
What are the defining characteristics of Arthropods?
Phylum with the most species(extremely diverse)
Molting exoskeleton
Segmented body plan
Segments fuse to form major body parts (distinct head, thorax and abdomen (post genital region) )
jointed appendages(legs and antennae)
Have well developed sensory organs including eyes, olfactory receptors and antennae
Some undergo metamorphosis
65
How does segmentation differ in arthropods and annelids?
Arthropod segments are more specialized(modified) than in annelids
almost identical segments in annelids
66
What are examples of arthropods?
insects, spiders milipedes, crabs
67
What are examples of arthropods?
insects, spiders milipedes, crabs
68
what are the 3 main groups of arthropods?
Chelicerates
Myriapods
Pan crustaceans
69
Chelicerates
Ex; spiders, horseshoe crabs scorpions ticks mites and sea spiders
Are named for clawlike feeding appendages called chelicerae
Two main body parts : Have an anterior cephalothorax(means head thorax) and posterior abdomen
Lack antennae and have simple eye
70
What are the 2 main groups of Chelicerates?
1. Arachnaids- Scorpions spiders ticks and mites (Have 6 pairs of appendages: the chelicerae and pedipalps)
2. Horseshoe crabs(“living fossils”)
71
Myriapods
Less specialized segments- far fewer are fused (similar to annelid worm)
- many body segments and one or 2 pairs of legs per segment
2 main groups; millipede and centipedes
Head has pair of antennae and 3 pairs of appendages modified as mouthparts including jaw like mandibles
72
Millipedes
have a large number of legs
Each trunk segment is formed from 2 fused segments and bears 2 pairs of legs
Herbivores
73
Centipedes
Carnivores
Often venomous
One pair of legs per segment
74
Pan crustaceans
Crustaceans and insects now recognized as a single clade (previously thought as completely separate monophyletic groups-molecular info gives us new info)
75
Insects
All insects have either 0 or 2 pairs of wings but some have been modified
Have dorsal aorta that acts as a heart that pumps blood from the bottom of the body and the blood trickles down the body (don’t transport oxygen and carbon dioxide in blood have little holes on side of body and trachea that perminate all body tissues and gases diffuse passively
Reproduction is usually sexual with separate male and female
76
How are deuterostomia defined?
Deuterostomia is defined primarily by DNA similarities not developmental similarities
77
What are examples of echinoderms?
Ex: sea stars brittle stars sea urchins feather stars sea cucumbers
78
What are the defining characteristics of Echinoderms?
Slow moving
sessile marine
deuterostome
larvae have bilateral symmetry
Adults have radial symmetry-(this radial symmetry is new not evolved from cnidarian radial symmetry)
Sexual reproduction is separate in male and females, release their gametes into the water
Possess endoskeleton (like us) extensions of which form the exterior spines
Most locomote using tube feet and water vascular system
Divided into 5 clades
79
Asterodia: sea stars and sea daises
```
Crawl along rock and coral
Hunt clams (eject stomach out to begin digestive process and then shove stomach in)
Very strong
```
80
Ophiuroidea: brittle stars
Look like star fish superficially (bigger than them don’t have tube feet)
Some are suspension feeders others are predators
Locomote by thrashing arms abt
Up to 60 cm in diameter
Some bioluminesce blue or green
81
Echionoidea: sea urchins and sand dollars
Have no arms but have 5 rows of tube feet
Sand dollars:
Bury themselves in sand
Eat small crustacean's plankton algae and detritus
Sea urchins:
Eat algae (or sessile or very slow-moving animals)
Very painful to step on
82
Crinoidea: sea lilies and feather stars
Live attached to the substrates by a stalk
Feather stars crawl by suing their ling arms
Both use their arms as suspension feeder
83
Holothuroidea: sea cucumbers
Lack spines endoskeleton is much reduced- don’t look like echinoderms
Elongated on their oral aboral axis
Have 5 rows of tube feet
some around the mouth are developed as feeding tentacles
Eat plankton and detritus
Some are eaten by humans
84
what do invertebrate and vertebrate chordates have in common?
All share a set of derived characters
Some only have these during embryonic development
notochord
dorsal hollow nerve cord, Pharyngeal slits
Postanal tail
HUMANS HAVE ALL 4 THINGS
85
Which phylum do chordates share a close relationship with?
echinoderms
86
What are the characteristics of all chordates?
bilateral symmetry with segmented bodies
belong to clade Deuterostomia
Both invertebrate chordates and vertebrate chordates
Ex: lancelets tunciates vertebrates, humans (vertebrates)
87
2 groups of invertebrate
2 groups of invertebrate (lancelets and tunicates) Deuterostomes that are more closely related to vertebrates than other invertebrates
88
describe the dorsal hollow nerve cord
develops from a plate of ectoderm that rolls into a tube located dorsal to the notochord
Resulting dorsal hollow nerve cord is unique to chordates
Nerve cord of the embryo develops into the central nervous system; brain spinal cords
89
describe the Pharyngeal slits
Allow water entering the body to exit without passing through the entire digestive tract
Function as suspension feeding devices in invertebrates
In vertebrates they have been modified for gas exchange and are known as gill slits
90
What do other invertebrate phyla have?
have ventral solid nerve cords
91
Lancelets
Live in marine sand
Most basal group of living chordates
As larvae they develop a notochord a dorsal hollow nerve cord lots of pharyngeal slits and post anal tail
Muscle segments develop from blocks of mesoderm called somites
Display key chordate characters as adults
Suspension feeders
92
What are some characteristics of Lancelets?
Live in marine sand
Most basal group of living chordates
As larvae they develop a notochord a dorsal hollow nerve cord lots of pharyngeal slits and post anal tail
Muscle segments develop from blocks of mesoderm called somites
Display key chordate characters as adults
Suspension feeders
93
What are some characteristics of Tunicates?
sessile
marine chordates that lack a backbone
Recent studies show they are more closely related to other chordates than lancelets
Larvae have chordate features
Suspension feeders
Once it settles on substrate it undergoes metamorphosis
adults are radially symmetric(novel trait like in echinoderms)
94
what are the defining characteristics of the vertebrates?
have all defining features of chordates but share a set of derived characters that distinguish them from other chordates :
multiple sets of Hox genes- (turn on and off during development, shows where something will go)
neural crest cells- Give rise to teeth some of the bones and cartilage of skull, neurons and sensory capsules
Make peripheral nerves
95
what are the most primitive chordates?
(the invertebrate chordates)
lancelets
tunicate
96
what are the most primitive vertebrates?
hagfishes
lampreys
Only members of vertebrates that lack jaws
Don’t have backbone
Notochord stays there whole life- act as skeleton
Primitive skeleton; cartilaginous vertebrae along the notochord (provides little or no protection to nerve chord)
97
Hagfishes
Have a small brain eyes ears and a nasal opening that connects with the pharynx
Rows of slime glands secrete a substance that absorbs water forming a slime to suffocate predators
Tie itself into knots to escape from its own slime
Eat dead and dying animals by entering their bodies
98
Lampreys (Petromyzontida)
Some are marine some are freshwater
Larvae Is a suspension feeder (like lancelet)
Skelton is made of cartilage- contains no collagen, stiff matrix of proteins
Most adults are parasites (drinking blood or eating flesh)
A few are notropic (they don’t eat)
Larval stage eats make body big as possible and adults don’t eat
99
What are the three main groups of gnathostomes?
1. Rays and sharks
2. Ray finned fishes(trout salmon most fish we identify as a fish)
3. Lobe finned fish
100
What are the 2 extant groups of Lobe finned fish?
Coelacanth
| Lungfishes
101
What are some Derived characters of Gnathostomes ?
Are named for their jaws, hinged structures that with the help of teeth enable them to grip food firmly and slice them
Forebrain is enlarged compared to other vertebrates
Lateral line system (A row of organs along each side of the body that are sensitive to vibrations in the surrounding water , can detect slight changes in water pressure)
102
Chondrichthyes (rays and sharks)
Skeletal rods (cartilaginous bones) modified into jaws (proper mouths widen dietary options)
Have a skeleton composed predominantly of cartilage
Vertebrae filled out to make a complete skeleton
Still only cartilaginous
Provides stiff structure for bigger muscles and improved swimming
Provides protection to nervous system
Electrical sensation; nostrils on shark can detect electrical activity of muscles of other animals
103
Rayfinned Fish
True bones (calcium phosphate based)
Swim bladder(Swim bladders arose from lungs
Allows it to float- improves buoyancy and swimming ability )
operculum (protects the gills allows breathing without swimming)
have rayed fins (little bones that form rays)
Bony extensions into fins for added strength
Most are oviparous
104
Lobe- Finned fishes
Fins are more lobe like (slightly limb like)
Some in shallow stagnant waters; lungfishes
some in deep sea( coelacanths)
tetrapods( most diverse out of the 3 groups)
105
What are the previous and current hypotheses about how lungfish evolved to amphibians?
Previous hypothesis:
Lunged fish dragged themselves from pond to pond
Those that did a better job survived and legs eventually evolved
THIS IS WRONG
Current hypothesis:
Lunged fish evolved four legs and a neck
Then they were able to drag themselves from pond to pond
106
Lungfishes
Generally found in freshwater
Developed true lungs (frow swim bladder)
Can breathe air (oxygen in short supply in shallow stagnant water)
Still have gills
Surface to gulp air into lungs connected to the pharynx
107
What are tetrapods?
are gnathosomes that have limbs
108
What are defining features of tetrapods?
vertebrate with 4 true legs
the 1st vertebrate to leave the water
Have limbs with digits instead of pectoral and pelvic fins
The head is separated from the body by a neck
The bones of the pelvic girdle to which the hind legs are attached are fused to the backbone permitting forces generated by the hind legs against the ground to be transferred to the rest of the body
Adults don’t have gills
109
Amphibians (class Amphibia)
No more gills in most adults (breathe with lungs)most larvae still need gills
Some breathe through skin and some have even lost lungs because they do this so well
Lay their eggs in water or moist environments- eggs lack a shell and dehydrate quickly in air (completely dependent on water)
Similar to plants moving onto land
110
Amphibians (class Amphibia)
No more gills in most adults (breathe with lungs)
most larvae still need gills
Some breathe through skin and some have even lost lungs because they do this so well
Lay their eggs in water or moist environments- (eggs lack a shell and dehydrate quickly in air, completely dependent on water)
Similar to plants moving onto land
ex- salamanders frogs and caecilians
111
Salamanders (urodeles)
Some are entirely aquatic some are land based (Ones that live on land walk with a side to side bending of the body )
Some are legless (lost their legs through evolution even though ancestors had legs)
112
Frogs
Better suited for life on land than salamanders
| Completely terrestrial in some groups (toads) (some live in desert and go to great lengths to maintain hydration)
113
Caecilians
Are legless nearly blind and resemble earthworms
Would be called worms if they were invertebrates
Absence of legs is a secondary adaptation
Inhibit tropical areas
More closely related to frogs than salamanders
Evidence shows most ancients group did have legs but got lost during evolution
114
What are amniotes?
Are tetrapod's that have terrestrially adapted eggs
115
What are Derived Characters of Amniotes ?
amniotic egg
the amnion the chorion the yolk sac and allantois – called extraembryonic membranes
waterproof shell (slows dehydration)
use their rib cage to ventilate their lungs
(This allowed them to abandon breathing over their skin and develop less permeable skin conserving water )
116
What are the benefits of the amniotic egg
Was a major evolutionary innovation allowing embryos to develop on land in a fluid filled sac thus reducing the dependence of tetrapod's on water for reproduction
117
What are the 2 major groups of amniotes?
reptiles
| mammals
118
What are the major extant groups of reptiles?
tuatara lizards snakes turtles crocodiles and birds
119
What are some characteristics of reptiles?
Full adaptation to life on land unlike amphibians which still relied on water
(This is due to waterproof skin)
Lay their shelled eggs on land (internal fertilization)
Unlike amphibians they have scales that contain protein keratin
(Help protect animals skin from desiccation and abrasion)
120
What does it mean that lizards and snakes are cold blooded?
Lizards and snakes are described as cold blooded (old term they do warm up and do thermal regulate but from external space)
They don’t use their metabolism extensively to control their body temp- they are ECTOTHERMIC
121
What does it mean to be ecothermic?
(non avian)
Absorb external heat as main source of body heat
Low energy demands (don’t need to eat much)
Can sometimes generate own body heat by contracting muscles such as by shivering
122
What does it mean to be endothermic?
body temperature is warmed by heat generated by their own metabolism
ex-birds
feathers originally evolved for thermal insulation
feathers later evolved for flight
This heat usually maintains a stable body temp higher than that of external environment
Have to eat a lot more food because you need to burn a lot of calories to maintain body temp
123
What are the defining characteristics of mammals?
Mammary glands(to produce milk)
Hair
Highly efficient kidneys( efficient at conserving water when removing wastes from the body )
Four-chambered hearts (more efficient with gas exchange like birds; amphibians and other reptiles have three; fish have two)
Large brains(especially in carnivores and primates)
Neocortex (6 layers), the cerebral cortex is especially large (most vertebra have 3 layers)
Differentiated teeth
124
What group of amniotes do mammals belong to?
synapsids
single temporal fenestra- a hole behind the eye socket on each side of the skull
HUMANS retain this feature
125
What are the 3 groups of mammals?
1. Monotremes
2. Eutherians
3. Marsupials
126
Monotremes
An egg laying mammal such as platypus or echinada (spiny anteaters )
Have hair and produce milk but lack nipples
Milk is secreted by gland on the belly of the mom
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Marsupials
Ex; kangaroos koalas and opossums
A mammal whose young complete their embryonic development inside a maternal pouch called the marsupium
Have higher metabolic rates and nipples that provide milk
Embryo develops inside the uterus
Marsupial is born very early and completes embryonic development while nursing
Held within pouch called a marsupium
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Eutherians
placental mammals
complete embryonic development in the womb
Have longer pregnancy than marsupials
Ex; anteater Humans
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Why are duck billed platypus odd?
1. They have bills and webbed feed like ducks
2. They lay eggs
3. They’re venomous
4. They produce milk but have no nipples
5. They have 5 pairs of sex chromosomes
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What are 3 groups of Primates
1. Lemurs lorises bushbabies
2. Tarsiers
3. Anthropoids(HUMANS)
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What are the 5 groups of extant apes ?
1. Gibbons
2. Orangutans
3. Gorillas
4. Chimpanzees
5. Hominins
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What are the 2 groups of Anthropoids(simians) ?
monkeys and apes
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What are the 2 groups of monkeys?
New world
| Old world
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What is the "issue" with the word monkey?
group monkeys is not monophyletic because apes aren't included
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What are characteristics of primates?
Most have hands and feet adapted for grasping and their digits have flat nails instead of narrow claws of other mammals
Skin ridges on their fingers
Have large brains and short jaws
All except humans have big toe that is separated from other toes
All have a thumb that is relatively movable and separate from fingers but monkeys and apes have a fully opposable thumb
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Hominin
throughout evolutionary history multiple hominin species coexisted today we are the only ones left
Homo sapeins and homo neanderthaiensis coexisted
Know that in the last 2-3 million years many hominin species coexisted
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Characteristics of humans
are mammals that have a large brain and bipedal locomotion
Humans stand up right and are bi pedal( walk on 2 legs)
Have a much larger brain than apes and are capable of language symbolic though artistic expression and manufacture tools
Have a reduced jawbones and jaw muscles along with shorter digestive tract
