Chordata Flashcards

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1
Q

What characterizes the phylum Chordata?

A

4 anatomic features

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2
Q

What does studying invertebrates in Chordata allow for?

A

Clues to the origins of vertebrates

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3
Q

What are the 3 subphyla of the phylum Chordata? Examples

A

1- Urochordata = tunicates
2- Cephalochordata = lancelets
3- Vertebrata = vertebrates

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4
Q

What are the 4 common features that all Chordatas have at some stage in their life?

A

1- Notochord
2- Dorsal hollow nerve cord
3- Pharyngeal slits
4- Post-anal tail

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5
Q

What is the notochord? When is it present? Where is it?

A

Present in all chordate embryos
Longitudinal, flexible rod
Between digestive tube and nerve cord

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6
Q

What is the notochord made from?

A

Large fluid-filled cells in stiff fibrous tissue

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7
Q

What does the notochord do?

A

Skeletal support

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8
Q

What does the notochord turn into in humans?

A

Gelatinous (Jelly) material of the disks between vertebrae

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9
Q

How does the dorsal hallow nerve cord develop?

A

In embryo - from plate of ectoderm that rolls into a tube

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10
Q

What does the dorsal hollow nerve cord develop into?

A

Central nervous system = brain and spinal cord

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11
Q

Where are the pharyngeal gill slits found? (3)

A

Connected to the pharynx, behind the mouth and to the outside of the animal

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12
Q

What does the pharyngeal gill slits do?

A

Allows water to enter mouth and exit without going through digestive tract

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13
Q

What does the pharyngeal slits function as in invertebrates of Chordata?

A

Suspension feeding devices

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14
Q

What does the pharyngeal gill slits turn into?

A

Slits and structures become - modified gas exchange (water vertebrates), jaw support, hearing and more

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15
Q

What is the post-anal tail?

A

Muscular tail that extends past the anus

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16
Q

What does the post-anal tail contain?

A

Skeletal elements and muscles

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17
Q

What does the post-anal tail do?

A

Pushing force for aquatic species

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18
Q

What is an example of the subphylum Urochordata?

A

Tunicates = sea squirt

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19
Q

Where are Urochordata found? How do they move?

A

Marine - sessile

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20
Q

How do Urochordata feed?

A

Suspension-feeders

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21
Q

Explain the process of suspension-feeding for Urochordatas

A

Water passes inside animal by
incurrent siphon -> gill slits -> ciliated chamber (atrium) -> food is trapped here -> water exits through excurrent siphon

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22
Q

What are Urochordata encased in?

A

In a tunic of cellulose-like carbohydrate

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23
Q

What of the 4 characteristics of Chordata are seen in young and adult Urochordata?

A

Young - all 4

Adult - only pharyngeal gill slits retained

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24
Q

What is an example of Cephalochordata?

A

Lancelets

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25
Q

What of the 4 characteristics of Chordata are seen in young and adult Cephalochordata?

A
Young = all 4
Adult = retain all 4
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26
Q

How do Cephalochordata feed? Explain

A

Suspension feeders - mucus nets across gills trap particles

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27
Q

How do Cephalochordata respire?

A

A little in part by pharynx and gill slits

Mainly across external body surface

28
Q

Where are Cephalochordata found? Do they move?

A

Found tail end buried

Frequently move burrow sites by swimming

29
Q

Explain how Cephalochordata swim

A

Contraction of chevron-shaped muscles flexes notochord and pushes body forwards

30
Q

How are the chevron-shaped muscles used for swimming developed in Cephalochordata?

A

From blocks of mesoderm - called somites

Arranged along each side of notochord in embryos

31
Q

What are the 2 stages of the evolution of vertebrates from invertebrates?

A

1- ancestral Cephalochordata evolved form oranges similar to larva form of Urochordata
2- vertebrates evolved from Cephalochordata

32
Q

What is the hypothesis of Cephalochordata evolving from larva Urochordata?

A

Paedogenetic

33
Q

Explain the hypothesis of Paedogenetic

A

Larva developed sexual maturity before metamorphism - if successful than natural selection would have reinforced this

34
Q

Is there any evidence of the hypothesis Paedogenetic?

A

No evidence supporting or contradicting it

35
Q

What are 3 distinct features of the subphylum Vertebrata?

A

1- head protected by cranium
2- backbone
3- bones

36
Q

What else is unique to Vertebrata?

A

Neural crest cells

37
Q

What are the 6 milestones of Vertebrata evolution?

A
1- cranium 
2- backbone
3- jaws/lungs
4- 4 limbs = colonized land 
5- amniotic eggs
6- mammary glands
38
Q

What are Gnathostoma?

A

Jawed vertebrates

39
Q

What does having a jaw mean for the Gnathostoma? (2)

A

1- wide range of feeding niches

2- evolved from gill arches in pharynx

40
Q

How did vertebrates move onto land? Common ancestor?

A

Became tetrapods

Common ancestor shared with fleshy finned fish

41
Q

What is the intermediate between an amphibian and a lobe-finned fish?

A

Tiktaalik

42
Q

What happened to the amphibians after colonizing land?

A

Diversified out = age of amphibians

43
Q

Though amphibians colonized land, they must spend most of life in water. Why?

A

They are dependent on water for reproduction

44
Q

Would amphibians be able to survive and thrive in rainforests?

A

Yes = moist habitat for reproduction

45
Q

How do amphibians respire?

A

Small lungs so have cutaneous gas exchange = gas exchange across moist skin

46
Q

What developed next for amphibians to move away from water?

A

Amniotic eggs

47
Q

What are amniotic eggs?

A

Drought-resistant = external water not necessary for production

48
Q

What are the 4 extraembryonic membranes?

A

1- yolk sac
2- chorion
3- allantois
4- amnion

49
Q

What is inside the amnion of an egg?

A

Amnion is the member with Amniotic cavity filled with amniotic fluid which protects the developing embryo

50
Q

Explain the allantois of the egg

A

Stores excreted waste of the developing embryo

51
Q

What is the yolk of the egg for? Where is it?

A

Nutrients and energy for the embryo

Contains within yolk sac

52
Q

What is the chorion of an egg?

A

Outside membrane before shell

53
Q

How are amniotes (eggs) classified?

A

How many temporal arches and opening on their skull

54
Q

What are the 5 groups of diapsids (reptiles)?

A
1- tuataras
2- lizards
3- snakes 
4- crocodiles
5- birds
55
Q

What are synapsids?

A

Mammals

56
Q

How do we distinguish diapsids (reptiles) for synapsids (mammals)?

A

All synapsids have mammary glands

57
Q

What are 2 other features to distinguish a mammal?

A

1- fur or hair

2- endothermy

58
Q

What is fur and endothermy? How is it used?

A

Endothermy - maintain body temp with metabolism

Homeothermy - maintain body temp requires fur

59
Q

What is the hypothesized reason as to why humans don’t have fur?

A

Reduce number of external parasites

60
Q

Mammals are divided into 3 groups, what are they?

A

Monotremes
Marsupials
Eutherials

61
Q

What are monotremes? Milk?

A

Egg-laying mammals

Milk secreted by mammary glands into milk patched

62
Q

What are marsupials?

A

Short gestation = young born underdeveloped and at birth crawl to mammary the gland to suckle milk

63
Q

What are Eutherials?

A

Longer gestation = developed at birth and weaned at early aged

64
Q

Explain the yolk of Eutherials

A

Reduced as embryo is nourished by mother’s blood = had placenta

65
Q

How are marsupials embryo nourishment different than Eutherials?

A

By yolk sac placenta = limited resources