Lesson 3 - Protochordates and the Origin of Craniates Flashcards

1
Q

what is present in protochordates

A
  1. bilateral symmetry
  2. pharyngeal slits
  3. notochord
  4. dorsal hollow CNS
  5. postanal tail
  6. endostyle
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2
Q
  • had bony plates and scales (armored fishes)
  • jawless vertebrates
  • small bony scales fitted tightly where there are no scales
A

ostracoderms

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3
Q

when did ostracoderms occur

A

late Cambrian period through the Devonian
(400-525 million years ago)

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4
Q

primitive fish that have many similarities to living hagfish and are the oldest vertebrates (530 my) ever found

A
  1. Myllokunmingia fengjiaoa
  2. Haikouichthys ercaicunensis
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5
Q

when did Myllokunmingia fengjiaoa
and Haikouichthys ercaicunensis live

A

530 million years ago

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6
Q
  • literally the ‘Chinese eel of good fortune’
  • earliest known chrodate
  • thought to be a fossil relative of modern lancelets
A

Cathaymyrus diadexus

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7
Q

proposed the establishment of Phylum Chordata in 1874

A

Ernst Haeckel

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8
Q

Subphylums under Phylum Chordata

A
  1. Urochordata
  2. Cephalochordata
  3. Craniata
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9
Q

subset of the larger group of animalia and share common features in development

A

basal deuterostomes

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10
Q
  • presence of calcium carbonate skeleton
  • presence of a secondary radial symmetry except in the most basal members
  • Cambrian to present
A

Echinoderms

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11
Q

example of echinoderms

A
  1. starfish
  2. sea urchins
  3. sea cucumbers
  4. sea daisies
  5. crinoids
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12
Q
  • acorn worms
  • marine organisms that live in the mud under shallow waters
  • fragile when handled
  • 1.5 meters
  • with invertabrate and chordate features
A

Hemichordates

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13
Q

added Hemichordates (acorn worms) to the Phylum Chordata

A

Bateson

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14
Q

why did Bateson add acorn worms to the Phylum Chordata in 1884

A
  1. dorsal, hollow nervous system
  2. gill slits
  3. short diverticulum of the gut (stomochord)
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15
Q
  • short diverticulum of the gut
  • not homologous with notochord
A

stomochord

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16
Q
  • marine chordates
  • notochord is confined to the locomotor tail of the free-living larval stage and lost during metamorphosis into sessile adults
  • enclosed within a delicate, nonliving, and colored transparent tunic
  • filter feeders
  • posses pharyngeal slits
A

Urochordata

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17
Q

urochordata are enclosed within a delicate, nonliving, and colored transparent __

A

tunic

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18
Q
  • sea squirts
  • solitary or colonial populations
  • larvae, have fleeting existence and do not feed (subsist on nutrients stored in the tissues)
A

Ascidians

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19
Q

three unequal regions of Hemichordates

A
  • proboscis
  • collar
  • trunk
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20
Q

parts of the Ascidian larva

A
  1. mouth
  2. pharyngeal slit
  3. atriopore
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21
Q
  • external opening through which water exits the body after passing through the pharyngeal slits
  • plays a key role in their filter-feeding system and respiratory process
A

atriopore

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22
Q

Features of the Subphylum Cephalochordata

A
  1. notochord
  2. dorsal, hollow nervous system
  3. pharyngeal gill slits
  4. ‘circulatory’ system - vertebrate pattern with pumping vessels but no heart
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23
Q

where is the locomotor musculature of subphylum cephalochordata found

A

muscles segments lie just under the skin

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24
Q

subphylum cephalochordata :
__ extend the entire length of the organism (locomotor muscle)

A

myomeres

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25
Q

skin of subphylum cephalochordata

A

single layer of epidermis

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26
Q

respiration of subphylum cephalochordata

A

cutaneous respiration

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27
Q

subphylum cephalochordata
- opens into the atrium which surrounds the pharynx laterally and ventrally
- water that enters here is another source of oxygen

A

pharyngeal slits

28
Q

how many pharyngeal slits are present in adult organisms of subphylum cephalochordata

A

60

29
Q

Pathway of water in subphylum cephalochordata

A

pharynx –> atrium –> atriopore

30
Q
  • extends from tip, to the rostrum, to the tip of the tails
  • muscular disc arranged like a long roll of coins separated by fluid-filled spaces
  • adaptation that facilitates burrowing in the sand
A

notochord

31
Q

where does the notochord extend from and to in subphylum cephalochordata

A

tip to rostrum to tip of tails

32
Q

skeletal structures of notochord in subphylum cephalochordata

A

fibrous rods that support
- pharyngeal bars
- buccall cirri
- mid-dorsal fin-like ridges

33
Q

subphylum cephalochordata
- hollow brain and dorsal nerve cord containing a central canal lined with ependymal cells
- brain has two subdivisions
- with cranial nerves
- spinal nerves – dorsal roots

A

nervous system and sense organs

34
Q

surrounds the brain and spinal cord of subphylum cephalochordata

A

leptomeninx

35
Q
  • light sensitive and pigmented
  • embedded within the ventrolateral walls of the spinal cord throughout its length
  • consists of a receptor cell and caplike melanocyte
A

Ocellus

36
Q

what are absent in subphylum cephalochordata

A
  • retinas
  • semicircular canals
  • lateral-line organs
37
Q

chemoreceptors of subphylum cephalochordata

A
  • buccal cirri
  • velar tentacles
  • tail
  • trunk
38
Q

monitor the incurrent water stream

A

velar tentacles

39
Q

what type of feeders are subphylum cephalochordata

A

filter feeders

40
Q

create a steady flow of water through the mouth and into the pharynx

A

cilia

41
Q

subphylum cephalochordata
- collective chamber of seawater
- laterally by oral hood, caudally by velum, perforated by the mouth, which opens into the pharynx

A

vestibule

42
Q

subphylum cephalochordata
- covered with sticky mucus
- retrieves some of the heavier food particles which directs it to the mouth and pharynx

A

wheel organ

43
Q

subphylum cephalochordata
- partially strain water as it enters the vestibule
- chemoreceptors monitor the food that enters

A

buccal cirri

44
Q

pathway of food in subphylum cephalochordata

A
  1. pharynx
  2. epibranchial groove
  3. midgut
  4. midgut ring
  5. hindgut or intestinal caecum
  6. anus
45
Q

digestive enzymes

A

midgut ring

46
Q

digestive juices for digestion

A

hindgut or intestinal caecum

47
Q

not prominent cavity in adult organisms in subphylum cephalochordata

A

coelom

48
Q

color of blood in subphylum cephalochordata

A

colorless
- lacks blood cells, platelets, and other formed bodies

49
Q

subphylum cephalochordata
- termination of venous system
- beginning of arteries
- not a pump

A

sinus venosus

50
Q

subphylum cephalochordata
- cells that collect the metabolic wastes

A

cyrtopodocytes

51
Q

subphylum cephalochordata
- footlike projections that make contact with an adjacent glomerulus

A

pedicels

52
Q

subphylum cephalochordata
- collects fluid from a cluster of cyrtopodocytes and empty into the atrium

A

nephridial tubule

53
Q

subphylum cephalochordata
- from cyrtopodocyte that propell tubulue fluids to the atrium

A

flagellum

54
Q

pathway of the excretory system in subphylum cephalochordata

A
  1. glomeruli
  2. pedicels
  3. cyrtopodocyte
  4. microvillar strands
  5. nephridial tubule
  6. atrium
  7. atriopore
55
Q

subphylum cephalochordata
- bulge into the atrium into which sperm or egg are shed
- gametes are flushed into the sea via atriopore

A

gonads

56
Q

subphylum cephalochordata are __ which means that ovaries and testes do not develop in the same individual

A

dioecious

57
Q

Amphioxus (a) vs Craniate (c):
cephalization

A

C = present
A = absent

58
Q

Amphioxus (a) vs Craniate (c):
paired sense organs

A

C = present
A = absent

59
Q

Amphioxus (a) vs Craniate (c):
notochord

A

C = present
A = present, no vertebral column

60
Q

Amphioxus (a) vs Craniate (c):
Pharyngeal slits

A

C = present
A = present, large in numbers and emptying into the atrium

61
Q

Amphioxus (a) vs Craniate (c):
hollow CNA

A

C = present
A = present, brains lack major subdivisions

62
Q

Amphioxus (a) vs Craniate (c):
segmented musculature

A

C = present
A = present, extend to tip of head

63
Q

Amphioxus (a) vs Craniate (c):
two layered skin

A

C = present
A = present, epidermis one cell thick

64
Q

Amphioxus (a) vs Craniate (c):
venous and arterial channels

A

C = present
A = present, no muscular heart

65
Q

Amphioxus (a) vs Craniate (c):
coelom

A

C = present
A = present, restricted in adults