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VERTEBRATE EVOL > Jawless-jawed and life in the water > Flashcards

Jawless-jawed and life in the water Flashcards

1
Q

evidence early vert evolution occurred in marine env:

A
  • earliest fossils found in marine deposits

- all non-vert chordates and deuterostome phyla are marine

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2
Q

odontodes: features and eg

A
  • first appearance of mineralised tissue
  • teeth-like structures that form in dermal layer of skin and overlaid w epidermis
  • eg. catfish have odontodes assoc w mouth
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3
Q

odontodes: function

A
  • mineral storage
  • protection
  • improved electroreception
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4
Q

early vert: vert w mineralised bone find

A

480-500mya

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5
Q

early vert: soft bodies vert found

A

520mya

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6
Q

early vert: fish-like creatures features and lacking

A
  • lack rays

- complex myomeres

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7
Q

world wide dist of ostracoderms and gnathostomes by:

A

400mya

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8
Q

extinct placoderms more closely related to living jawed/jawless fish:

A
  • jawed fish
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9
Q

myxiniformes: hagfish- features

A
  • eel-like scavengers
  • produces copious slime
  • 1-15 gill openings (species dependent)
  • lack true vert
  • simple kidneys
  • single semi-circular canal
  • single terminal nasal opening
  • horny plates of keratin (vs mineralised) in mouth
  • horny teeth on mm tongue can be extruded
  • degenerate eyes
  • 6 tentacles
  • large blood sinuses, low BP
  • 3 chambered heart
  • accessory hearts in liver and tail
  • heart is ANEURAL
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10
Q

myxiniformes: hagfish- reproduction and embryonic dev

A
  • almost unknown
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11
Q

peteromyzontiformes: lamprey- features

A
  • intermediate btw hagfish and gnathostomes (anatomy wise)
  • 2 semicircular canals: body orientation and momentum
  • heart inn by vagus nn (like gnathostomes)
  • active ion transport across skin
  • well dev kidneys: good control of hydrostatic pressure
  • useful for anadromous lifestyle (migration)
  • 7 pairs gills: pump water through mouth, out gills
  • but when attached to prey, ventilate back/forth through gills
  • large eyes, well dev pineal gland (close to nasal opening)
  • teeth keratinised
  • oral gland secretes anti-coagulant so feed on hosts uninterrupted
  • super rich diet, simple digestive tract
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12
Q

peteromyzontiformes: lamprey- unique features

A
  • single nasal opening connects to pituitary (hypophysis)

- unknown function

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13
Q

peteromyzontiformes: lamprey- lifestyle

A
  • most adults live in sea, some in lakes as fish parasites
  • migrate to freshwater to spawn
  • females builds nest in stream riffle, male wraps and fertilises eggs depositing into nest
  • 2 wks hatch into amoceotes larvae (burrow into soil and filter feed)
  • this stage up to 3 yrs
  • metamorphose into adults, drift downstream to sea
  • adults live to 2 yrs
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14
Q

peteromyzontiformes: lamprey- name phases

A
  • spawning
  • larval
  • transforming
  • parasitic
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15
Q

why important to study jawless fish in regards to early evol of vert:

A
  • fossil record not helpful
  • but can’t assume rep ancestral vert (highly specialised niches: scavenger and parasite)
  • hagfish eg. CNS reflects but others like eye loss most likely derived/ hard to interpret
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16
Q

condonts: elements

A
  • small mineralised teeth-like fossils
  • og thought to belong to invert
  • but assigned to true vert when discovered fossilised impressions
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17
Q

condonts: features

A
  • clear myomeres (V shaped)
  • well defined heads
  • large eyes
  • fins w fin rays
  • entire clade extinct 200mya
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18
Q

condonts: current phylogeny places them

A
  • btw lamprey and gnathostomes
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19
Q

ostracoderms: features

A
  • paraphyletic group
  • encased in dermal bone, well dev brains
  • all had central dorsal fin, some had true pectoral fins w assoc girdles and skeletal fin supports
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20
Q

ostracoderms: more closer to living jawed/jawless fish

A
  • closer related to jawed vert
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21
Q

ostracoderms: extinction

A
  • some say emergence of gnathostomes pushed ostracoderms to extinction (lived side by side for 50mya)
  • also coincides w mass invert extinctions
  • suggest catastrophic shift in env conditions
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22
Q

gnathostome: dev of jaws

A
  • probs started out as support for improved respiration vs. eating
  • once evolved, predation possibility and opened new niches
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23
Q

gnathostome: main obv distinctions btw jawed/jawless

A
  • jaws w teeth
  • paired pectoral and pelvic fins
  • duplication of HOX genes
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24
Q

gnathostome: other key innovations- jawless to jawed

A
  • jointed branchial arches
  • hypobranchial mm
  • 2 nares
  • first gill slit: spiracle
  • 3 semicircular canals
  • conus arteriosus (controls blood flow)
  • horizontal septum dividing epaxial and hypaxial mm
  • vert w centra and ribs
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25
Q

jaws and teeth: features

A
  • most likely evolved separately
  • teeth came from denticles already existing in some shape/form as seen on todays shark skin
  • placoderms (earliest jawed vert had jaw, no teeth)
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26
Q

jaws and teeth: seen in shark

A
  • ancestral situation where teeth form in skin
  • rest on jaw bone
  • new teeth roll forward in a whorl to replace old teeth
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27
Q

jaws and teeth: bony fish and tetrapods (incl ancestral and modern eg.)

A
  • teeth embedded into jawbone
  • ancestral form: like pleurodont where teeth set in shelf on inner side of jawbone
  • also seen in modern amphibians
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28
Q

jaws and teeth: acrodont teeth and eg.

A
  • teeth fastened to top of ridge, absence of socket

- most common in teleosts

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29
Q

jaws and teeth: thecodont teeth and eg.

A
  • teeth fastened in sockets and held in place by ligs

- most common mammals

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30
Q

hypobranchial mm: features

A
  • assoc w existing branchiomeric mm
  • allows animals form strong suction action
  • for ventilating gills
  • also suck in prey
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31
Q

vertebra: features- ancestral gnathostomes

A
  • dev more complex vert through time
  • ossified dorsal arches, protect nn cord (neural arch),
  • matching pair on ventral side (hemal arch)
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32
Q

vertebra: features- tetrapods

A
  • notochord more less replaced by series of well dev vert acting as scaffolding for axial mm
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33
Q

vertebra: features- recent gnathostomes

A
  • vertebral centrum/and or central elements which ribs articulate
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34
Q

vertebra: features- mammals

A
  • all sorts of spines

- interlocking processes unlike ancestral vert

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35
Q

ribs: features and assoc parts

A
  • gnathostome invention
  • offer further scaffolding upon axial mm: better locomotion
  • axial mm clearly arranged into ep/hypaxial segments divided by horizontal septum
  • middle of mm pack, lateral line collects vibration info (sent to ear)
  • 3rd semicircular canal allow movement and orientation in 3D space
36
Q

soft tissue: ostracoderm

A
  • well dev brain
  • cerebellum
  • olfactory tracts
  • lack 3rd semicircular canal
37
Q

soft tissue: gnathostomes

A
  • evolved myelin sheaths
  • increase efficiency of NS
  • 3 semicircular canals
  • conus arteriosus in heart: elastic reservoir to maintain uni-directional high pressure pumping sys
  • specialised duct connecting gonads to cloaca, for sperm/egg
38
Q

fins: features

A
  • guidance sys in 3D
  • unpaired fins of midline: control roll and yaw
  • pectoral, pelvic fins: control pitch, and breaks
  • caudal fin: increase SA of tail, more thrust
39
Q

fins: tribasal

A
  • connection from pectoral fins (in sharks)

- three elements of fin articulating w girdle

40
Q

gills: ancestral og

A
  • ancestral vert had both int/ext arches
  • alternatively lost in cyclostomes and gnathostomes
  • morphological changes due to changing timing of dev genes
41
Q

gills: transition btw gills and jaw

A
  • likely gill arches evolved to enhance fill ventilation

- changes co-opted to perform new functions as jaws

42
Q

gills: features

A
  • once produce powerful suction for gill ventilation, easy for using to forage
  • first arch must be articulated so open/close mouth
  • hyper/branchial mm dev to help power opening/closing -added stress so arch stronger, second gill recruited for structural support
43
Q

jaws: features and name arches

A
  • vert jaw derived from branchial arches historically assoc w gills
  • 1st gill arch: mandibular arch
  • 2nd: hyoid arch (supports 1st)
  • those post arches: support gills
  • most vert no hole btw 1st/2nd, some present as spherical in sharks/fish
44
Q

devonian gnathostomes: list 4 jawed vert (and whether extinct or not)

A

still exists:

  • sharks,
  • bony fish

extinct:

  • placoderms
  • acanthodians
45
Q

devonian gnathostomes: ostracoderms important features

A
  • large and diverse group
  • paraphyletic
  • grouped based on morphology
  • some more primitive/ more recently derived taxa in group
46
Q

devonian gnathostomes: acanthodians (spiny sharks)

A
  • traditionally grouped w bony fish, molecular evidence suggests not group at all
47
Q

devonian gnathostomes: placoderms- features

A
  • covered in bony plates, typically ant end
  • distinct set head plates linked via joint to rest of body: head can move independently
  • endoskeleton mineralised on edges only (perichondral) vs bony fish complete ossification (endochondral)
  • during Devonian times, dom and most diverse vert
  • some 8m length
  • majority wiped out by later Devonian event
48
Q

placoderms: teeth, soft features, reproduction

A
  • most lacked true teeth, modified dermal plates projecting from jawbones
  • later species evolved true teeth
  • not much known about soft bits, evidence in Aus:
  • myomeres weakly W shaped, lack clear distinctions btw epaxial and hypaxial sections
  • some: internal fertilisation, modified anal fins resembling male sharks
  • also may had embryos inside specimen
49
Q

acanthodians: features

A
  • named after strong spines assoc w fins
  • probs not single clade, dist all over gnathostome heritage
  • most diverse during Devonian period in freshwater (started out as marine group)
  • fusiform caudal fin suggest midwater taxa
  • some species 2+ paired fins: pectoral, anal
  • wide diversity of lifestyles, some w teeth also had whorls similar to sharks
50
Q

water living: features and facts

A
  • gravity insig in water vs. huge effect on terrestial vert
  • low viscosity of air: wind resistence neglible, but in water good hydrodynamics is vital
  • 800x denser than air
  • 55x more viscous than air
  • 40x less O2
  • water conducts heat 25x faster than air
51
Q

oxygen:

A
  • much harder to extract from water
  • need to pass over gills w high SA
  • by buccal pumping, ram ventilation
  • blood vessels in gills arranged to max uptake:
  • deoxy blood flows one direction, fully oxy water opp direction
  • counter current= O2 diffusion gradient maximised from water to blood
52
Q

buoyancy: features and eg.

A
  • fish effectively made of water, neutral buoyant (no effort to maintain position in water column)
  • bony fish: swim bladder on doral side wedged btw vert column/ peritoneal cavity (body vol- 5% marine teleosts, 7% freshwater teleosts)
53
Q

buoyancy: adjust position in water column- primitive and more derived fish

A
  • to swim up/down water column, need to adjust pressure
  • primitive fish: valve connecting stomach to burp air out/ gulp air and force back in
  • more derived fish: changes in vol by secreting gas from blood v into/out of swim bladder
54
Q

buoyancy: define physosomous fish and eg.

A
  • have link btw swim bladder and gut
  • more primitive fish
  • eg. trout
55
Q

buoyancy: rete mirabile

A
  • despite diff of primitive/more derived fish
  • both have this aka gas gland
  • enable excretion of O2 into swim bladder even at incredible depths
  • coz pressure in deep sea, rete mirabile have to be v long to overcome gradient
56
Q

buoyancy: define physoclistous fish

A
  • no connection btw swim bladder and gut

- more derived fish

57
Q

fish sense: name important properties in water (3)

A
  • light/ colour
  • mechanical disturbance
  • chemical cues
58
Q

fish sense: light and eg.

A
  • water rapidly absorbs light
  • red hardly penetrates, most colours lost in first 100m of water
  • only blue light persists afterwards
  • surface fish nearly all tetrachromatic, spherical lens coz refractive index of water
  • other fish, vision waste so depend on other senses
59
Q

fish sense: mechanical disturbance

A
  • works v well underwater
  • most bony fish has well dev lateral line
  • neuromasts detect displacement of water
  • also hav typical vert internal ear, for orientation and hearing
60
Q

fish sense: chemical cues

A
  • spread nicely underwater
  • already in solution
  • many fish sense chemicals 1 part/ billion
61
Q

electroreception: why and define electrocytes and eg.

A
  • also works well as water conducts electricity
  • electrosensitivity likely ancient vert trait
  • some fish: electrocytes (modified mm cells) generate electricity to stun prey, communicate or navigate
  • eg. weak electric fishes
62
Q

electroreception: sharks

A
  • network (ampullae of Lorenzini) on head
  • hone electrical discharge from mm and nn activity of prey
  • also picks up earths magnetic field
63
Q

electroreception: echidna and platypus

A
  • pre good electrosensitivity for foraging

- may evolved independently

64
Q

water and ions: features, waste and eg.

A
  • srs issue for all vert esp aquatic ones to control ions
  • skin highly permeable (not equally to everything)
  • vert control water/ion balance by actively/passively passing molecules from inside/outside vice versa
  • also deal w waste (ammonia) toxic product of protein decay
  • kidneys play huge role in both
65
Q

kidneys: nephron

A
  • fundamental unit is nephron
  • millions in kidney producing urine
  • extracts foreign substances and waste products from blood
  • control salt and water balance
66
Q

nephron: glomerulus

A
  • structure unique to vert

- arteriole under pressure leaks ultrafiltrate into bowmans capsule

67
Q

osmoregulation: hagfish

A
  • don’t achieve iron conc. diff from env =isotonic to sea water
  • other vert hav lower salt conc.
    1. salt move into marine vert
    1. water tries to leave
  • cartilaginous fish counteract by having high urea lvls in blood
  • opp for freshwater fish
68
Q

osmoregulation: define stenhaline

A
  • fish that remain in either salt/fresh water entire lives

- thus fixed physiology

69
Q

osmoregulation: define euryhaline

A
  • move btw fresh/salt water

- more complicated physiology

70
Q

osmoregulation: marine teleost and eg.

A
  • keep as much water as possible, excrete excess ions
  • marine teleosts drink alot of seawater and pump ions across stomach into blood to encourage water follow
  • gills pump Cl- out and Na follows
  • small glomeruli, lack distal convoluted tubule
  • produce lil but highly conc. urine
71
Q

osmoregulation: Coelacanths and eg.

A
  • sharks
  • high urea to prevent salt in, like coelacanths
  • water actively flows across gill membranes
  • sharks don’t need to drink
  • plenty of water, glomeruli large, great filtration rates
  • ions follow water across gills but unlike marine teleosts, membranes relatively impermeable to ions
  • excess salt secreted by rectal gland
72
Q

osmoregulation: freshwater teleosts and amphibians

A
  • salt tries to escape, water coming in
  • teleosts reasonably impermeable skin
  • huge water across gills to breathe
  • both amphibians and fish produce huge vol urine, kidneys overtime to extract excess water from blood
  • nephrons actively pump ions back into bloodstream from ultrafiltrate
  • fish also hav Cl- ion pumps in gills to actively move Cl from water to blood
  • causes diffusion grad and Na travels across passively
73
Q

nitrogenous waste- teleosts: waste product

A

ammonia

74
Q

nitrogenous waste- teleosts: excrete where

A

skin, gills, urine

75
Q

nitrogenous waste- teleosts: cost

A

low

76
Q

nitrogenous waste- teleosts: toxicity

A

high

77
Q

nitrogenous waste- teleosts: water conservation

A

low

78
Q

nitrogenous waste- mammals: waste product

A

urea

79
Q

nitrogenous waste- mammals: excrete where

A

urine

80
Q

nitrogenous waste- mammals: cost

A

med

81
Q

nitrogenous waste- mammals: toxicity

A

med

82
Q

nitrogenous waste- mammals: water conservation

A

med

83
Q

nitrogenous waste- reptiles (birds): waste product

A

uric acid

84
Q

nitrogenous waste- reptiles (birds): excrete where

A

urine

85
Q

nitrogenous waste- reptiles (birds): cost

A

high

86
Q

nitrogenous waste- reptiles (birds): toxicity

A

low

87
Q

nitrogenous waste- reptiles (birds): water conservation

A

high

VERTEBRATE EVOL (6 decks)

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