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Zoology Semester 1 > Biodiversity - animals > Flashcards

Biodiversity - animals Flashcards

1
Q

Approximately what percent of animals are vertebrates?

A

5%

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2
Q

How many common ancestors do animals have?

A

One - monophyletic group

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3
Q

What are the morphological features of animals?

A
  • Eukaryotes
  • multicellular, held together by collagen
  • Heterotrophic, feed by ingestion (usually)
  • Muscle and nervous tissue unique
  • Lack cell walls (instead supported by extracellular collagen matrix
  • Unique cell junctions
    • Tight junctions
    • Desmosomes
    • Gap junctions
  • hox genes (regulate form and function of animal development - complexity correlates with number of hox genes)
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4
Q

What are the life history features of animals?

A
  • Most reproduce sexually
  • Life cycle dominated by diploid stage
  • Small flagellate sperm fertilises non-motile egg (heterogametes)
  • Blastula (hollow ball of cells) in early development
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5
Q

What is the hollow inside of a blastula called?

What occurs after the blastula stage?

A

Blastocoel
- gastrulation (invagination) occurs, forming a gastrula with endoderm, ectoderm and in most animals mesoderm, as well as a blastopore

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6
Q

What is the common ancestor of all animals believed to be?

A

A colonial heterotrophic flagellate similar to a choanoflagellate protozoan
- closely resemble simple metazoan cells (collar of microvillae for filter feeding, single flagella (resembling cilia in animals), similar mitochondrial structure & DNA evidence)

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7
Q

Ontogeny reflects…

A

phylogeny (evolutionary history)

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8
Q

Animals can be … or … symmetrical?

A

Radially, bilaterally

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9
Q

Gastrulation results in…

A

at least 2 tissue layers (endoderm and ectoderm)

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10
Q

Radiata are … whereas bilateria are …

A

Diploblastic, triploblastic

- bilateral symmetry leads to cephalisation (development of CNS) and active lifestyle

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11
Q

What is the coelom like in pseudocoelomates?

A

Not completely lined with mesoderm - e.g. roundworms Nematoda)

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12
Q

What do acoelomates have?

A

A solid body between the digestive tract and outer body wall - lack digestive tract or incomplete without anus - e.g. flatworms

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13
Q

What are the benefits of having a coelom (body cavity)?

A
  • protection
  • allows organ growth
  • allows movement (“hydrostatic skeleton”) when combined with muscles
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14
Q

What are the four factors which differentiate protostomes from deuterostomes?

A
  • cleavage (protostomes spiral cleavage, deuterostomes radial
  • cell fate during early development (determinate in protostomes, indeterminate in deuterostomes)
  • coelom formation (schizocoelous in protostomes -solid masses split-, enterocoelous in deuterostomes - infolds)
  • Fate of blastopore (in protostomes the mouth develops from the blastopore, in deuterostomes the anus develops from the blastopore)
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15
Q

Platyhelminthes..

A

used to have coelom, then lost it (what plonkers!!)

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16
Q

Parazoa have…

A

No gastrulation
No true tissues (but some specialised cells)

  • simplest animals
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17
Q

What is phylum Porifera?

A

Sponges

  • simple body plan
  • lack muscles, nervous system, organs
  • asymmetrical
  • rigid, sessile, perforated sack
  • feed passively by filter feeding
    • water drawn in through porocytes and out of osculum
    • Choanocytes are specialist feeding cells and line the inside - have flagellum - resembles ancestral choanoflagellate
  • usually hemaphrodites that reproduce sexually
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18
Q

What are the radiata?

A

Have radial symmetry

Diploblastic

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19
Q

What is the phylum Cnidaria?

A

Jellyfish, corals, hydra, sea anemones

  • simple form (blind sac with a gastrovascular cavity
  • Mouth = anus
  • polyp (mouth-up) form and medusa (mouth down) form
  • No brain but simple nerve network
  • contractile bundle of microtubules in epidermis act like muscles
  • mesoglea acts a bit like a hydrostatic skeleton
  • tentacles covered in cnidocytes for defence and capturing prey (+nematocysts)
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20
Q

What are the true jellyfish?

A

Scyphozoan

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21
Q

What are the box jellyfish?

A

Cubozoan

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22
Q

Hydrozoan is a colony of…

A

polyps, e.g. portuguese man-o-war

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23
Q

What are corals?

A

Anthozoans

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24
Q

What are the two groups of protostomes?

A

Lophotrochozoa (crown of cilia) and ecdysozoa

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25
Q

What are the platyhelminthes?

A

Flatworms phylum

  • lost coelom
  • mesoderm -> true organs, organ systems and muscles
  • cephalisation and sensory development
  • lack gas exchange and circulatory organs
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26
Q

What are the 3 classes of platyhelminthes?

A

Turbellaria - free-living marine flatworms with ganglia an eyespots
Trematoda - parasitic flukes, usually of vertebrates
Cestoidea - parasitic tapeworms with hooks and proglottids

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27
Q

What is the phylum annelida (lophotrochozoan)?

A

Segmented worms

  • metamerism (linear and segmented)
  • Coelom divided by septa
  • Circular blood vessels + paired metanephridia
  • circular and longitudinal muscles in body wall
  • dorsal and ventral blood vessels (closed circulatory system)
  • Digestive tract has specialised regions
  • 3 classes (earthworms, marine segemented, leeches)
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28
Q

What are the 2 most important evolutionary features of the annelids?

A
  • Well-developed coelom that acts as a hydrostatic skeleton, provides body space for storage and organ development, acts as a cushion for the internal organs
  • metamerism - allows specialisation of regions of the body
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29
Q

What is the third group of lophotrochazoans?

A

Mollusca (snails, clams, squids)

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30
Q

What are the characteristics of molluscs?

A
  • Similar body plan (foot, visceral mass, mantle + many have radula (rasping tongue))
  • trochophore larval stage (with band of cilia)
  • not segmented
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31
Q

What are the 3 main classes of molluscs?

A
  • Gastropoda
  • Bivalvia
  • Cephalopoda
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32
Q

What are gastropods?

A

Snails, limpets, slugs

  • shelled forms can retreat into shell when threatened
  • most are marine, with terrestrial requiring damp locations
  • in some snails mantle cavity serves as a lung
  • radula to graze on algae and plants or even for predation
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33
Q

What are bivalves?

A

Clams and oysters

  • shell divided into two halves
  • body and foot laterally compressed
  • head and radula lost
  • gills adapted for filter feeding
  • generally sedentary lifestyle
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34
Q

What are cephalopods?

A

Squids, octopuses, cuttlefish

  • external shell much reduced or absent in most
  • Still have mantle present
  • nautilus is only living shelled cephalopod (living fossil)
  • Beak like jaws
  • some are venomous to immobilised prey
  • foot modified into a muscular siphon and tentacles to propel them
  • highly active predatory lifestyle
  • only molluscs with closed circulatory system - 3 hearts - blue blood - complex eye
  • chromatophores provide camouflage
  • well developed CNS and brain, capable of memory and learning
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35
Q

Apart from the lochotrophozoa, what is the other type of protostome?

A

Ecdysozoa
- molting - undergo ecdysis shedding of exoskeleton)

  • nematodes and arthropods
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36
Q

What are the nematoda?

A

Roundworms

  • coelom not fully bounded by mesoderm (pseudocoel)
  • cylindrical unsegmented body tapers at tail
  • DNA closer to arthropods
  • Cuticle shed during growth
  • complete digestive tract with anus
  • lacks circulatory system (nutrients transported in pseudocoel)
  • pseuodocoel and cuticle act as hydrostatic skeleton
  • Move by thrashing around
  • both free-living and parasitic types
  • may be most abundant multicellular animal
  • c. elegans one of most important model organisms in developmental biology and genetics
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37
Q

What are the arthropods?

A

Jointed exoskeletons (chitin and protein cuticle)

  • 2/3 species are arthropods
  • Waterproof exoskeleton must be molted for organism to grow (vulnerable to predation and dessication)
  • paired appendages
  • well developed cephalisation and sensory organs - well-defined head
  • metameric
  • open circulatory system (haemolymph bathe internal organs)
  • gills (aquatic)/tracheae (terrestrial)
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38
Q

What are the subgroups of arthropods?

A
  • Trilobites
  • chelicerates
  • crustacea
  • Uniramia
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39
Q

Trilobites

A
  • extinct (permian)
  • little tagmatization
  • extensive metamerism
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40
Q

Chelicerates

A

Spiders, horseshoe crabs, ticks

  • cephalothorax (lacking antennae) and abdomen
  • First appendages are pair of chelicerae for feeding, then pedipalps (sensing or feeding), the 4 pairs of legs
  • abdomen usually lacks legs
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41
Q

Crustacea

A
  • two pairs of antennae
  • 3 pairs of mouthpart appendages
  • thorax has legs, which are branched
  • abdominal segments have swimming appendages
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42
Q

Uniramia

A

Centipedes (chilopoda) and millipedes (Diplopoda - 2 legs per segment)

  • unbranched appendages
  • Highly metameric

Insects (Hexapoda)

  • 3 tagmata (head, thorax, abdomen)
  • one pair of antennae
  • efficient gas exchange system through well-developed tracheal system in which tubes lead to every cell in the body
  • Spiracles regulate airflow and water loss
  • Sophisticated sensory organs, e.g. compound eye
  • well-developed nervous system allowing complex behaviour
  • one or two pairs of wings derived from outfoldings of cuticle
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43
Q

What are the potential origins of insect wings?

A

Heat absorption
Gliding from vegetation to ground
Gills or fins in aquatic ancestor

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44
Q

What are the echinoderms?

A

Starfish, sea urchins, brittle stars

  • sessile or slow-moving
  • Secondary radial symmetry (larvae are bilateral)
  • Often radiate from central disc with 5 arms (pentamerous)
  • Endoskeleton made from calcareous ossicles or plates that are DERIVED FROM MESODERM
  • Water Vascular System comprising canals and sucker-like tube feet that function in locomotion, feeding and gas exchange
    • ring canal, ampullae, tube feet
  • no cephalisation
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45
Q

What are the 5 major classes of echinoderms?

A
  • Asteroidea (starfish) - evert stomach, can regenerate arms (totipotent cells) - prey on molluscs
  • Ophiuroidea (brittle stars) - distinct central disc, long highly mobile arms, often scavengers
  • Echinoidea (sea urchins/sand dollars) - no arms but rows of tube feet, move slowly, grazers, jaws
  • Crinoidea (sea lilies/feather stars) - ancient, use arms in suspension feeding
  • Holothuroidea (sea cucumbers) - lack spines, reduced endoskeleton, elongate oral axis, tube feet adapted as tentacles for feeding

+ new class concentricycloidea (sea daisies)

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46
Q

When did echinoderms and chordates separate?

A

500MYA

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47
Q

What are the 4 key characteristics of the chordates?

A
  • Notochord - long flexible rod lies between digestive tract and nerve cord in embryo, skeletal support
  • Dorsal hollow nerve chord - rolled up plate of dorsal ectoderm - front end becomes brain if present
  • Pharyngeal slits - slits in ‘throat’ region of the digestive tract that allow water to pass through
  • Muscular post-anal tail - unlike protostomes, chordates don’t usually end in anus
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48
Q

What are the 3 sub-phyla of chordates?

A

Urochordates, cephalochordates (craniates), vertebrates (also craniates)

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49
Q

What are the urochordates?

A

Subphylum tunicates or ‘sea squirts’

  • Adult is sessile, U-shaped filter-feeder (only has one chordate characteristic)
  • larvae has all four classic chordate characteristics
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50
Q

What are the cephalochordates?

A

Subphylum lancelets or branchiostoma (Amphioxus)

  • Live in the sand
  • Lance-shaped
  • Swimming motion similar to fish with side to side undulations produced by segmented muscles
  • all four chordate characteristics as adult
  • No real head, brain, sensory organs, heart or jaws
  • No true fins but fin-like folds along body
  • mouth surrounded by cirri that strain and direct food to mouth, food then collected in the pharyngeal slits, filtered by mucus
  • muscle segments (Develop from blocks of mesoderm arranged along the notochords)
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51
Q

What are the characteristic features of subphylum vertebrata?

A
  • Formation of neural crest during development, cells become braincase, teeth, PNS
  • pronounced cephalisation with brain and sensory organs in the head
  • Segmented vertebral column forms main axis of the body
  • closed circulatory system with ventral cha mbered hearts - pumps oxygenated blood through complex system of capillaries and arteries
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52
Q

When did the first vertebrates appear?

A

Around 550MYA

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53
Q

What does agnatha mean?

A

Without jaws

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54
Q

Most agnatha are..

A

extinct

55
Q

The earliest agnatha were…

A

Ostracoderms - heavily armoured jawless fish

  • covered with bony plates and scales surfaced in enamel and dentine (like teeth) to protect against invertebrate predators
  • Plates around mouth acted as shovel
  • lacked pectoral fins - probably poor swimmers
56
Q

The modern agnatha are….

A

Hagfish and lampreys - eel-like vertebrates that lack paired fins and jaws - no armour - cartilaginous skellington

57
Q

What are the most primitive fish?

A

Hagfish - most are scavengers that feed on dead animals - enter body through opening and eat from the inside out

  • the only vertebrates that are isotonic with seawater - all others must maintain osmotic balance, therefore the ancestor of all subsequent vertebrates lived in freshwater
  • Produce a shit tonne of mucus “slime”
  • no eyes
58
Q

Lampreys are..

A

predators or parasites of fish

  • freshwater or marine
  • cartilaginous ‘vertebral column’
59
Q

What do the gnathostoma have?

A

hinged Jaws

2 pairs of appendages

60
Q

What is it thought was the original function of gills?

A

Suspension feeding

61
Q

What were the first jawed fish?

A

Placodermi

  • devonian predators
  • heavily armoured, some with cleaver-like plates for biting
62
Q

What are the Chondrichthyes?

A

Cartilaginous sharks and rays

  • Many covered in small tooth-like placoid scales
  • Well-developed jaws and paired fins
  • five pairs of gill pouches
  • acute sense for predatory lifestyle
    • lateral line system for detecting pressure changes
    • some have electroreceptive organs in the head
    • nostrils with cups-shaped smell receptors
    • sharp non-coloured vision
  • species can be oviparous, ovoviviparous, or viviparous
  • heterocercal tail (top part longer) + wing-like pectoral fins provide lift as body negatively buoyant
  • short intestine with a spiral valve that increases SA area for absorption
  • always must swim or pump water over gills to get oxygen
  • no swim bladder
63
Q

Sharks are very resistant to…

A

viruses - dogfish have squalamine which combats several viruses which cause human diseases (dengue fever and hepatitis for example)
- positively charged molecule - sticks to negatively charged membranes and removes other positive proteins (inc those from viruses)

64
Q

What are the bony fish?

A

Osteichthyes

  • endoskeleton made of bone (calcium phosphate)
  • flattened bony scales
  • lateral line system for detecting pressure changes
  • Gas-sac organ - either lung or swim bladder (allows to maintain buoyancy, may act as O2 resevoir, evolved from outpocket of pharynx)
  • no spiral valve, instead coiled intestine
65
Q

What does an operculum do?

A

Covers gills

66
Q

Pharyngeal muscles act like…

A
  • bellows to keep water flowing across the gill
67
Q

What are the 3 classes of osteichthyes?

A
  • lobe-finned fish (actinistia)
  • lungfish
  • ray-finned fish
68
Q

What are the actinistia?

A

A class of osteichthyes

  • lobe-finned fish
  • heavy pectoral and pelvic fins supported by extensions of the skeleton and muscle
  • large bottom-dwellers that may have walked in the sea bed
  • coelocanth is the only living species
69
Q

What are the dipnoi?

A

Lungfish - live in stagnant ponds and swamps, with lungs and nostrils to provide oxygen by breathing air in their oxygen-depleted environments

70
Q

What are the actinopterygii?

A

Ray-finned fish (most living forms of fish - teleosts)

  • reduced scales for increased mobility
  • fins free from being wings, adapted as brakes or rudder
  • Homocercal tail allows better manoeuverability
  • more efficient jaw - maxilla now free and articulated
71
Q

Why did the movement of tetrapods onto land occur?

A

Cyclic weather and drying conditions predominated in the late Devonian so there was less habitat for fish.
Also there was abundant prey on shore
Also the potential to escape fearsome marine predators

72
Q

What were the first tetrapods?

A

Fish that lived in shallow waters - with heavy skeletal structures, lungs and internal nostrils
- e.g. tiktaalik

73
Q

Fossil amphibian anatomy closely resembles fossil…

A

lobe-finned fishes

74
Q

What challenges did the first early amphibians have to overcome?

A
  • UV light
  • Physical support (as no water medium)
  • Sensory modification
  • Variable temperature (no water to act as temp buffer)
  • Water loss through breathing air
  • Water loss through skin and excretion
  • Desiccation of sperm and eggs
75
Q

How did the first amphibians evolve to suit life on land?

A
  • Lungs
  • Epidermis with chromatophores (pigments cells) to absorb UV, keratin to reduce water loss, mucous to protect skin and reduce water loss, and a vascularised dermis permitting gas exchange but with limited range
  • Skeleton and paired appendages - strong vertebrae, pentadactyl limb, modified ribs attach pelvic girdle to vertebrae, pectoral girdle held in place by muscles
  • sensory adaptations - lateral line system lost in adult stage, tear ducts, eyelids, evolution of an ear
  • metabolic adaptations - divided intestine, gills/lungs, 3 chambered heart, winter hibernation
76
Q

What do amphibians require for reproduction?

A

Water - jelly egg masses subject to dessication and aquatic tadpole larvae

77
Q

What were the earliest amphibians?

A

Subclass labrynthodonts

  • named for complex tooth shape
  • semi-aquatic
  • gave rise to reptiles
78
Q

What are orders of modern amphibians?

A

Urodela - newts and salamanders
Anura - frogs and toads
Apoda - caecilians

79
Q

What does paedomorphic mean?

A

Development slows down and sexual maturity is reached in the larval stage - neoteny

  • e.g. tiger salamander - axolotl
  • metamorphoses if enough iodine in the water
  • use gills rather than lungs
80
Q

Frog ribs are fused to…

A

their vertebrae

81
Q

caecilians are..

A

legless and blind

- worm-like through convergent evolution

82
Q

How many frog species have become extinct since the 1970s?

A

200 species that we know about
+ high rates of deformity in some places

Causes:

  • habitat loss
  • Introduced predators
  • toxic contaminant
  • CHYTRID FUNGUS which damages keratin in frog skin, reducing their capacity to breathe
  • climate change & global warming, reducing pond depths, increasing UV on eggs, reducing disease resistance, allowing high rates of chytrid fungus infection –> mortalities and deformities
83
Q

What is an amniote?

A

An animal that produces an amniotic egg - a self-contained waterproof chamber for development, eliminating the larval stage - contains 4 membrane layers that are not part of the embryo - does not need to return to water to reproduce

84
Q

What are the layers of the amniotic egg?

A
  • Outer shell - hard, waterproof and protective but allows gas exchange - allows oxygen to reach embryo
  • Albumin - contains some nutrients, primarily cushions and protects embryo + air space to feed air to embryo
  • chorion - surrounds embryo and other membranes and regulates gas exchange
  • yolk sac - accumulation of nutrients used to nourish embryo
  • allantois - stores nitrogenous wastes (+involved in gas exchange
  • Amniotic cavity with amniotic fluid - surrounds and protects embryo
85
Q

What are the 3 main branches of amniotes (based on skull morphology)?

A

Anapsid - no fenestra (windows in skull) - turtles + extinct reptiles
Diapsid - two fenestra - other reptiles and birds
Synapsid - one fenestra - mammals

86
Q

The class reptilia is…

A

paraphyletic (not monophyletic) - multiple lineages, not single common ancestor

87
Q

What defines the reptile class?

A

Amniotic egg, no feathers (so not birds), no mammary glands (so not mammals)

88
Q

What does the reptile class include?

A

Turtles, tortoises, lizards, snakes, crocodiles, alligators, caimans, gharials, tuataras

89
Q

What are the features of reptiles?

A
  • Dry scaly keratinised skin (prevents dessication) - must breathe through lungs not skin
  • Internal fertilisation, eggs laid on land
  • Ectothermal (don’t have to eat as much and don’t lose energy to metabolic processes, but are sluggish when it is cold and must spend time sunbathing to gain heat)
  • Heavier more ossified skeleton than amphibia, stronger joints, clawed toes
  • More complex muscle and nervous systems
  • 4 chambered heart separates oxygenated blood
90
Q

Which period is known as the “age of the reptiles”?

A

Mesozoic

91
Q

How many evolutionary radiations of reptiles were there?

A

2
1st - anapsid (turtles), diapsid (lepidosaura and archosauria), synapsid (mammals) lineages
2nd - Archosauria radiated, producing crocodiles, pterosaurs and dinosaurs

92
Q

What extant reptiles are archosauria?

A

Crocodiles

93
Q

What extant reptiles are lepidosauria

A

lizards, snakes

94
Q

There is evidence to suggest that dinosaurs could sustain rapid motion, suggesting that some may have actually been…

A

endothermic

  • legs beneath body
  • vascularised bones
  • predator prey ratios similar to modern mammal communities
  • however mesozoic consistently warm
  • small SA to V ration - low SA for heat to escape
95
Q

Order chelonia

A

Turtles, terrapins and tortoises

  • marine, freshwater + terrestrial forms
  • teeth replaced by sharp horny plates
  • bony dermal plates fuse with ribs + vertebrae to form a carapace and plastron
  • retractable limbs and head to protect vulnerable soft parts
96
Q

Order squamata

A

Lizards and snakes

97
Q

How are snakes highly specialised?

A
  • loss of limbs, elongate body form - likely from burrowing lizard ancestor
  • loss of eyelids, clear spectacle
  • many specialisations for finding prey, e.g. jacobson’s organ senses smell, pit organs sense heat
  • jaws extremely flexible with 5 moveable joints for large prey
98
Q

Order crocodilia

A

Alligators, crocodiles, caimans, gharials

  • all extant species adapted for life in water - broad flattened tail, ears, eyes and nostrils on top of head
  • most closely related to dinosaurs
99
Q

Class aves

A

Birds - monophyletic group

  • defined by the presence of feathers
  • reptile features include scaly legs and amniote egg
100
Q

How are birds adapted for flight?

A
  • hollow bones with cross-struts (reduce weight, add strength)
  • reduced organs (e.g. females have 1 ovary)
  • no teeth, food ground in a gizzard (centre of gravity)
  • keratin bill - often highly modified
  • large pectoral muscle anchored to keel with rigid fused vertebrae gives power for flight
  • wings aerofoil shape
  • pentadactyl limb
  • feathers held together with barbs and hooked barbules
  • feathers are outgrowths of skins made from keratin - not living
101
Q

What are contour feathers for?

A

Overly body and give body outer shape, cover front of wings

102
Q

What are down feathers for?

A

Lack hooks - trap air for insulation, keep bird warm

103
Q

What are flight feathers for?

A

Trailing edge of wings - large strong feathers for flight

104
Q

What are filoplumes for?

A

Accompany contour feathers and probably have sensory function

105
Q

what did birds evolve from?

A

Bipedal dinosaur therapod

106
Q

birds have no … in their tails

A

vertebrae

107
Q

What are the 3 hypotheses for the origin of flight?

A

1 - feathers aided rapid running, jumping then gliding when catching insect prey
2 - feathers aided running up inclines, then gliding
3 - ancestors were climbers, feathers evolved as an adaptation for gliding to the ground

108
Q

What are the two main superorders of birds?

A
  • Ratites (“raft shaped” or flat chest) - vestigial wings, large powerful legs, lack keel but wide sternum (suggests lost flight), once thought primitive but has evolved at least 4 times, cassowary & emu, ostrich, rhea, kiwi - not monophyletic
  • Carinates (have keel or carina) - 24 orders, great variety adapted to many environments and ways of life (e.g. penguins, waders raptors), 60% are passeriformes (perching birds)
109
Q

Mammals are…

A

endothermic vertebrates

  • posses hair made of keratin, with fat = insulation
  • skin glands including mammary (modified sweat glands)
  • 4 chambered heart
  • anatomical features such as limbs carried below body, synapsid skull with large braincase, jaw consisting of a single bone, ear comprising 3 ossicles derived from jaw bones
110
Q

mammalian teeth are…

A

heterodont - for different functions

111
Q

Early mammalian teeth were..

A

tribosphenic

112
Q

The oldest mammal fossils pre-date…

A

birds

113
Q

The mammal ancestor was a now extinct…

A

therapsid reptile

114
Q

The mesozoic mammals were small…

A

nocturnal insectivores

115
Q

Why did mammals radiate very rapidly after the cretaceous extinction event?

A

Lost reptile competitors

116
Q

What are the prototheria?

A

Monotremes (“one opening” - reproductive and digestive tract have combined opening - called the cloaca)

  • egg laying
  • possess hair and mammary glands (but no nipples)
  • only found in australia and new guinea
  • two forms - platypus and echidna
  • Platypus has webbed feet, short thick fur, bill for feeding on invertebrates
  • echidna has long snout, sticky tongue, heavy claws
117
Q

What are the metatheria?

A

Marsupials - pouched mammals

  • embryo nourished by yolk (mostly), then placenta
  • short gestation, young altricial (<1% of mother’s weight)
  • young have strong forelimbs and claws, climb into marsupium where mammaries are located
  • invested few resources at point of birth so young cheap to abort at times of nutritional stress
118
Q

What are the eutheria?

A

Placental mammals

  • complete development in the uterus
  • most extant orders evolved between 50-70mya
  • longer pregnancy than marsupials - placenta nutrient highway from mother to offspring
  • 4 major lineages of eutherian mammals based on molecular data
119
Q

What are the afrotheria?

A

Proboscids (elephants), sirenians (manatees), hyraxes, aardvarks
- herbivorous

120
Q

What are the xenarthra?

A

Sloths, anteaters, armadillos

  • radiation occured in south america so don’t occur anywhere else
  • reduced or no teeth
121
Q

What are the laurasiatheria?

A

Carnivores (cats, dogs, seals - carnassial pair of teeth for slicing), artiodactyls (even-toed ungulates - sheep, pigs, deer - elaborate ruminant stomach - tusks, horns, antlers), cetaceans (whales and dolphins - toothed and baleen types - monophyletic with artiodactyls), perissodactyls (odd toad ungulates - horses, rhinos - simple single stomach, different teeth (lophodont)), chiropterans (bats - mega- and microchiroptera), core insectivores (moles, shrews, hedgehogs - most primitive eutheria - nocturnal)

122
Q

What are the boreoeutheria?

A

Rodents (most specious mammals, rootless incisors, hypsodont molars, most pass food twice), Lagomorpha (rabbits and hares - rootless incisors, hypsodont molars), tree shrews, primates

123
Q

What does the dental structure of primates suggest that the ancestor was?

A

a small cretaceous insectivore

124
Q

What primate features suggest they were originally arboreal?

A
  • Supple shoulder joints for brachiation (swinging)
  • Hands for climbing
  • Claws replaced by nails
  • sensitive fingers
  • thumb
  • eyes front facing with binocular vision
  • enlarged braincase and optic lobe
  • single birth with long parental care
  • omnivorous diet and lack of specialisation in teeth
125
Q

What are the prosimians?

A

“pre monkeys”

  • lemurs (madagascar) - mostly nocturnal, eyes small and not binocular, pronounced nose, small brain, large olfactory regions (smell)
  • tarsiers - mostly nocturnal, huge eyes and optic regions, reduced nose and olfactory regions
126
Q

What are the anthropoids?

A

Monkeys, apes, hominids

  • monophyletic group
  • reduced nose, sense of smell
  • primary communication visual, well-developed sense of vision
  • reliance on visual rather than olfactory social cues, elaborate social organisation in many groups
  • tactile senses of digits well-developed, tips have ridges for grip
  • large brain
127
Q

What are the anthropoids divided into?

A
  • Platyrrhini - new world monkeys - widespread nostrils, flat nose, prehensile tail common, all arboreal, 3 premolars, non-opposable thumbs
  • Catarrhini - old world monkeys, apes (inc humans) - narrower nose, downward pointing nostrils “drop nose”
128
Q

What are the cercopithecoidea?

A

Old world monkeys

  • ischial callosities, often surrounded by coloured skin
  • never prehensile tail
  • 2 premolars
129
Q

What are the hylobatidae?

A

Gibbons - adapted for brachiation

130
Q

What are the pongidae?

A

Chimpanzees, gorillas, orangutans

  • larger body size
  • lack tail
  • tendency towards upright posture
  • very large brain, well-developed social structure
131
Q

What are some human specialisations?

A
  • Elaboration of brain and behaviour, speech
  • increased cranial capacity (1.4L, 0.4 in chimps, 0.5 in gorillas)
  • prolonged post natal development (neoteny)
  • erect posture
  • large, strong thumb, fingertip broad, enabling precise grip
132
Q

What are the modifications to the human skull?

A
  • Enlargement of frontal region of braincase (gives high forehead)
  • shortening of snout and face
  • jaws receding, shortened tooth row and rounded shape, reduction of the canines
  • reduction of jaw bone but development of chin
  • reduction in jaw musculature and ridges on skull for muscle attachment
133
Q

How large was the australopithecus brain in relation to the homo?

A

1/3 of the size

Zoology Semester 1 (16 decks)

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