Protochordates and The Origin of Craniates Flashcards

1
Q

Also known as enterocoelomates because their coelom develops through enterocoely

A

deuterostomes

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2
Q

proposed a taxonomic classification of deuterostomes

A

Ernst Haeckel (1874)

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3
Q

Four extant phyla of deuterostomes

A

Xenoturbellida
Echinodermata
Hemichordata
Chordata

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4
Q

Invertebrate extant phyla of deuterostomes

A

Xenoturbellida
Echinodermata

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5
Q

coelom forms when the mesoderm splits, doe

A

protostomes

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6
Q

the coelom forms when the mesoderm pinches off through the process of enterocoely, merges with coelom

A

deuterostomes

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7
Q

Closest relatives of vertebrates along with the hagfish
Provide clues to the invertebrate origin of animals with backbones

A

Protochordates

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8
Q

Protochordates are composed of subphylums:

A

Hemichordata
Urochordata
Cephalochordata

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9
Q

Phylum
Unique calcium carbonate skeleton
Secondary radial symmetry in adults
Bilateral symmetry in early life stage

A

Phylum Echinodermata

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10
Q

Commonly known as acorn worms
Vermiform bottom dwellers found in shallow mud water
Fragile and can reach up to 5 feet in length
can be in freshwater

A

Phylum Hemichordata

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11
Q

Proposed classification of Hemichordata in 1870 by Gregenbaur

A

Enteropneusta

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12
Q

Proposed classification of Hemichordata in 1874 by Haeckel

A

Phylum Chordata

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13
Q

Proposed classification of Hemichordata in 1884 by Bateson

A

Subphylum Hemichordata

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14
Q

Subphylum Hemichordata example

A

acorn worm

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15
Q

Bateson’s considerations placing Phylum Hemichordata under Phylum Chordata

A

Collar nerve cord is dorsally located with lumen

Have slits that open to the exterior in lateral walls of the foregut

Have a stomochord, short diverticulum of the foregut

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16
Q

findings ultimately showed that it is not homologous to the chordate notochord

short diverticulum of the foregut

A

stomochord

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17
Q

Class

Wormlike acorn worms

Mucus-covered body

Active proboscis collects food in mucous strands

Cilia carry particles to groove at the edge of the collar, then to the mouth

Thrust proboscis into mud and ingest mud to extract the organic matter

Sexes are separate

Fertilization is external

At least one species undergoes asexual reproduction

A

Class Enteropneusta

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18
Q

connects protocoel with a proboscis pore to the outside in Class Enteropneusta

A

Buccal diverticulum

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19
Q

________ of body musculature forces excess water out through the gill slits in Class Enteropneusta

A

Contraction

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20
Q

Roll of gill pores is part of _________ that connects with series of gill slits in sides of pharynx in Class Enteropneusta

A

branchial system

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21
Q

Primarily ciliary-mucus feeders using U-shaped gill slits

A

Class Enteropneusta

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22
Q

Class Enteropneusta has a vessel that expands into a sinus and heart vesicle above the buccal diverticulum

A

Middorsal vessel

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23
Q

Blood enters network of blood sinuses called _______ and then through an extensive system of sinuses to the gut and body wall in Class Enteropneusta

A

glomeruli

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24
Q

in Class Enteropneusta, consists mostly of a

A

subepithelial plexus

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25
Q

in Class Enteropneusta, formed by an invagination of ectoderm (hollow in some species)

A

Dorsal nerve cord (neurocord)

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26
Q

in Class Enteropneusta, a ________ larva develops similar to that of echinoderm larva

A

ciliated tornaria

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27
Q

Basic plan similar to that of Enteropneusta

Small animals, usually 1 to 7 mm in length

Many individuals may live together in collagenous tubes (zooids are not connected)

Ciliated grooves on tentacles and arms collect food

Both dioecious and monoecious species

Asexual reproduction is by budding

A

Class Pterobranchia

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28
Q

Body divided into three regions in Class Pterobranchia

A

proboscis, collar and trunk

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29
Q

Similarties between hemichordates and echinoderms

A

Bilaterally symmetrical larvae

Similar in certain developmental processes, in muscle proteins, etc.

In addition to the dorsal nerve cord, there is another one on the ventral surface, as in invertebrates

Deuterostomous development

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30
Q

Sequence analysis of the gene encoding the small subunit of rRNA supports a deuterostome clade by which taxa

A

Echinodermata
Hemichordata
Chordata

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31
Q

should be classified close both to echinoderms and protochordates but in a separate taxon

A

Hemichordates

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32
Q

Marine chordates

Notochord is found in the locomotive tail of the free-living larval stage

Enclosed in tunics

Filter feeders

A

Subphylum Urochordata

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33
Q

Subphylum Urochordata 3 classes

A

Ascidiacea
Larvacea
Thaliacea

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34
Q

Urochordata class

Sea squirts are the best known urochordate

Can either be solitary or colonial

Larvae are tiny and have a fleeting existence lasting for a few minutes to a few days and do not feed

Presence of uninucleated striated muscles

A

Class Ascidiacea

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35
Q

Urochordata class

Nervous system consists of dorsal hollow nerve cord, several ganglia and nerves

Definitive blood cells and a functional heart does not differentiate until metamorphosis

Adhesive papillae attaches the larva to a permanent substrate

A

Class Ascidiacea

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36
Q

used for statoreception in Class Ascidiacea

A

Otoliths

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37
Q

used for photoreception Class Ascidiacea

A

Ocellus

38
Q

Class Ascidiacea water pathway

A

Respiratory water  mouth  pharynx  gills  atrium  atriopore

39
Q

Class
Notochord is resorbed and becomes source of nutrients during metamorphosis

Nervous system location is altered and rearrangement of viscera takes place

Water flows through slits into atrial cavity and out through excurrent siphon

A

Class Ascidiacea

40
Q

Class
Called sea squirts because they discharge a jet of water when disturbed

A

Class Ascidiacea

41
Q

______ becomes the incurrent siphon (anterior)
Class Ascidiacea

A

Larval mouth

42
Q

______ becomes the excurrent siphon (dorsal)
Class Ascidiacea

A

atriopore

43
Q

Class Ascidiacea
Water entering the incurrent siphon passes through a ciliated perforated

A

pharynx with an elaborate basketwork

44
Q

Class Ascidiacea
Feeding depends on the formation of a mucous net that is secrete by the ____

A

endostyle

45
Q

Class Ascidiacea
on gill bars of pharynx pull mucus into a sheet

Particles trapped in sheet are worked into a rope and carried back to the esophagus and stomach

Polyp becomes a filter feeder because of this

A

Cilia

46
Q

circulatory system of Class Ascidiacea

A

Heart drives blood first in one direction, then in reverse

47
Q

gland that samples incoming water and may have an endocrine function

A

Subneural gland

48
Q

with a single ovary and a single testes and fertilization is external in Class Ascidiacea

A

Hermaphroditic

49
Q

Adult sea squirts retain 2 of 5 chordate features

A

Pharyngeal slits
Endostlye

50
Q

Tadpole larvae have all 5 chordate characteristics

A

true

51
Q

class

Planktons on surface water or deep sea

With a long body and a long flat locomotive tail supported by a notochord

Retain larval form yet is sexually mature

Resemble the larval stages of other urochordates

A

Class Larvacea

52
Q

class
Surrounded by a thick, delicate hollow sphere of mucus interlaced with passages for water entry produced by the larva

Phytoplankton and bacteria trapped on a feeding filter inside the sphere are drawn into the branchial basket through pulsating movement

A

Class Larvacea

53
Q

Class Larvacea
When ______become clogged with wastes, they are left behind and a new sphere is built

A

feeding filter

54
Q

Colony may be linear or it may consists of a floating water-filled sac

Incurrent aperture projects into the sea and excurrent aperture empties into the saccular chamber

Colonies move with water current

Only one order has a free-living larval stage and has a very short-life span

A

Class Thaliacea

55
Q

class Thaliacea has No notochord to be described

A

true

56
Q

the correct morphological development or evolution

A

Pedomorphosis preceding Peramorphosis

57
Q

Any outcome arising from evolutionary changes in developmental rates (see heterochrony) that involves the addition of new stages to the end of the ancestral development sequence.

A

Peramorphosis

58
Q

process of development in which an organism retains juvenile characteristics into adulthood,

A

Pedomorphosis

59
Q

Generally called amphioxus (sharp at both ends) or lancelet (little spear)

Marine forms in sandy beaches

Filter feeders by burrowing in the sand, making a U-turn and having the oral hood protruded

Hollow nerve cord lies above the notochord

Pairs of spinal nerve roots emerge at each trunk segment

Anterior nerve cord is not enlarged, yet is homologous to vertebrate brain

Sexes are separate

Gametes are set free in the atrium and pass out through atriopore

Fertilization is external

Larvae soon hatch and gradually assume the shape of adults

A

Subphylum Cephalochordata

60
Q

Subphylum Cephalochordata Genera:

A

Branchiostoma and Asymmetron

61
Q

has the five distinctive characteristics of chordates in simple form

A

Amphioxus

62
Q

in Amphioxus, Water enters the mouth directly driven by cilia in the _______

A

buccal cavity and pharynx

63
Q

in Amphioxus, Water passes through pharyngeal slits where food is trapped in mucus secreted by the

A

endostyle

64
Q

in Amphioxus, Food is moved through gut via cilia concentrated in areas called the

A

ileocolic ring

65
Q

in Amphioxus, Food particles separated from mucus are passed into _______ where they are phagocytized

A

in Amphioxus,

66
Q

in Amphioxus, Filtered water leaves body by an

A

atriopore

67
Q

Closed circulatory system is complex but lacks a heart in Amphioxus

A

true

68
Q

how does blood flow in amphioxus

A

Blood is pumped by peristaltic contractions in ventral aorta, passes upward through branchial arteries in pharyngeal bars to paired dorsal aortas

Blood moves by microcirculation through tissues and returns to ventral aorta

69
Q

Blood lacks ________ and mainly transports nutrients in amphioxus

A

erythrocytes and hemoglobin

70
Q

Sense organs are simple, including an unpaired _______ that functions as a photoreceptor in amphioxus

A

ocellus

71
Q

Subphylum Cephalochordata
is a diverticulum resembling the vertebrate pancreas in secreting digestive enzyme

A

Cecum

72
Q

Subphylum
possesses features that suggest the vertebrate plan

Trunk muscles resemble vertebrate patterns

Posses basic circulatory plan of vertebrates

A

Cephalochordata

73
Q

Differences of Cephalochordata From Vertebrates

A

Almost no cephalization and no paired sense organs
No vertebral column
Has pharyngeal slits in large numbers
Brain lacks major craniate subdivisions
Segmented musculature extends to the anterior tip of the head
One-layered external integument
No muscular heart
Coelom is found in adult forms only

74
Q

Similarities of Cephalochordata From Vertebrates

A

Big five

Segmented or metameric musculature

Two layered skin

Blood flow direction in arterial and venous channels

Homologous homeobox gene clusters

75
Q

have been found in very old rocks, indeed, predating the origin of the vertebrates

A

Fossil cephalochordates

76
Q

earliest known cephalochordate found in South China (Early Cambrian)

A

Yunnanozoon

77
Q

cephalochordate fossil found in BC, Canada (Middle Cambrian)

A

Pikaia

78
Q

eel-like; earliest known chordata fossil somewhat similar to Pikaia

A

Cathaymyrus

79
Q

A Vertebrate Larva

A

Ammocoete Larva

80
Q

Shows evidence that vertebrates share a common ancestor with protochordates

Notochord that commence from the midbrain and continues to the end of the body (no vertebral column)

A

Ammocoete Larva

81
Q

Dorsal hollow nerve cord develops as of the amphioxus but with a tripartite brain

Seven pair of gill slits open to the exterior for respiration

Skin is multilayered

Body wall musculature provides locomotion

Filter feeders

A

Ammocoete Larva

82
Q

Hypobranchial groove in ammocoetes sink and becomes the

A

subpharyngeal gland

83
Q

Ammocoetes and amphioxus difference in diverticulums

A

Ammocoetes have a solid liver diverticulum which the amphioxus has a saccular diverticulum at the same location but are not analogous

84
Q

Food particles are trapped in mucus produced by the ________which is homologous to the hypobranchial groove of amphioxus

A

endostyle

85
Q

Larva that has a:

Circulatory system with heart (sinus venosus, atrium and ventricle) and RBC

Sense organs are present such as otic vesicles (precursor of membranous labyrinth but not for hearing), olfactory sac (chemoreception associated with feeding) and pineal and parapineal organs (act as photoreceptors)

Paired lateral eyes eventually form but are rudimentary

A

Ammocoete Larva

86
Q

which collect body fluid for processing and excretion in Ammocoete Larva

A

funnel-like nephrostomes

87
Q

in Ammocoete Larva, Fluids are expressed into the coelom via

A

glomeruli

88
Q

in ammocotes, _increase in number as larvae elongates and lead to ducts which empties to the exterior near the anus

A

Tubules

89
Q

Gonad is paired early in larval life and becomes unpaired later in ammocoetes

A

true

90
Q

Bottom-dwelling organisms from the Late Cambrian

Sucked up organic material from the sediment like vacuum cleaners

Most ancient agnathan or jawless fish

Extinct by the Devonian because they could not compete with other jawed fishes

A

Ostracoderms

91
Q

Cartilaginous internal skeleton
Dorsoventrally flattened
Cartilaginous internal skeleton
Dorsoventrally flattened
Dorsal eyes
Armored head

A

Ostracoderms