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COMPARATIVE ANATOMY > AMPHIOXUS > Flashcards

AMPHIOXUS Flashcards

1
Q

All chordates have at some time during their life a _____________, _____________< and __________________.

A

notochord, dorsal nerve cord, and gill slits

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2
Q

4 Subphyla of Phylum Chordata

A

Hemichordates (acorn worms)
Urochordata (tunicates)
Cephalochordates (amphioxus)
Vertebrata

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3
Q

2 genera of Cephalochordates

A

Branchiostoma
Asymmetron

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4
Q

it means sharp at both ends

A

Amphioxus

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5
Q

genus of Amphioxus

A

Branchiostoma

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5
Q

it is transparent and has an elongated but laterally compressed body

A

Amphioxus

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6
Q

What do amphioxus lacks?

A

paired appendages; skull; vertebrae; kidney; heart; brain

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7
Q

What makes amphioxus differ from fishes?

A

it lacks skull, vertebrae, brain, heart and kidneys

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8
Q

Why is the body of amphioxus semitransparent?

A

single cell epithelium and gelatinous connective tissue

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9
Q

angularly shaped muscle masses

A

myomeres

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10
Q

feeding position of amphioxus

A

burrowing into the sand with its head exposed

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11
Q

how do amphioxus obtains its food?

A

getting food from the seawater that flows over its head at regular intervals

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12
Q

water-filtering mechanism of Amphioxus

A

Wheel Organ

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13
Q

extends the entire length of the body

A

Median dorsal fin

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14
Q

An expanded continuation of the median dorsal fin at the posterior end of the body

A

Caudal fin

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15
Q

An anterior continuation of the caudal fin extending to the atriopore.

A

Ventral fin

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16
Q

Opening of an internal cavity, the atrium, located just in front of the ventral fin.

A

Atriopore

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17
Q

snout-like anterior end of the body that projects over the oral hood

A

Rostrum

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18
Q

Twenty-two stiff tentacle-like structures projecting from the free edge of the oral hood. used for taste

A

Buccal cirri

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19
Q

sixty angularly shaped muscle segments, also known as myotomes

A

Myomeres

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20
Q

connective tissue partitions separating the myomeres

A

Myosepta

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21
Q

row of rectangular bulging masses located beneath the ventral ends of the myomeres

A

Gonads

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22
Q

A pair of integumentary folds that extend along the ventrolateral surfaces from the anterior pharyngeal region almost to the atriopore.

A

Metapleural folds

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23
Q

Funnel-shaped membrane located at the ventral part of the anterior end of the body. Helps direct the water vortex, created by the wheel organ

A

Oral hood

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24
Q

Funnel-shaped cavity enclosed by the oral hood

A

Vestibule

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25
Q

Internal connective tissue rods that are present as supporting elements in both the dorsal and ventral fins; absent in caudal fin

A

Fin rays

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26
Q

supporting rod that extends almost the entire length of the body

A

Notochord

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27
Q

elongated cylindrical mass of nervous tissue that lies above the notochord

A

nerve cord

28
Q

linear series of pigment cells lying along the ventral wall of the nerve cord; serve as photoreceptors

A

Ocelli

29
Q

A mass of pigment cells located at the anterior end of the nerve cord.

A

Eye spot

30
Q

A series of finger-like projections, lined with cilia, that lies on the inner lateral and dorsal walls of the oral hood.

A

Wheel Organ

31
Q

vertical membrane located just behind the base of the wheel organ; regulate the amount of water entering the pharynx

A

Velum

32
Q

opening in the velum

A

Mouth

33
Q

short tender projections extending from the margin of the velum that rings the mouth; prevent sand particles from passing into it

A

velar tentacles

34
Q

the chamber, interrupted by gill slits, that extends from the mouth to the intestine

A

pharynx

35
Q

slender parallel oblique bars, supported by branchial rods, that make up the side wall of the pahrynx

A

Gill bars

36
Q

Large cavity surrounding the pharynx; its ventral boundary is visible as a line extending below the pharynx to the atriopore.

A

Atrium

37
Q

digestive tube that extends from the pharynx to the anus

A

Intestine

38
Q

pouch that projects forward as an outpocketing of the intestine

A

Hepatic diverticulum

39
Q

outer cellular layer of the body; composed of single layer columnar cells; covered by an acellular cuticle

A

Epidermis

40
Q

short projection from the dorsal midline region that is supported by the gelatinous fin rays

A

Dorsal fin

41
Q

masses of muscle under the skin, separated by connective tissue partitions, the myosepta

A

Myomeres

42
Q

triangular structure located in the midline, slightly ventral to the dorsal fin

A

Nerve cord

43
Q

very narrow cavity of the nerve cord

A

Neurocoel

44
Q

central cavity of the oral hood

A

Vestibule

45
Q

The thickened ciliated epithelial masses of the __________ are found on the inner oral hood wall.

A

Wheel Organ

46
Q

These project down from the ventrolateral corners of the body.

A

Metapleural folds

47
Q

lies in the wrinkled body wall between the metapleural folds; when it contracts, it compresses the atrial cavity dorsal to it from the side, thus expelling its water

A

transverse muscle

48
Q

narrow cavity limited laterally by gill bars extend between the notochord and transverse muscle

A

pharynx

49
Q

2 types of gill bars

A

Primary and Secondary Gill Bars

50
Q

Smaller gill bars and do not contain a coelomic cavity near their lateral end

A

Secondary or tongue bars

51
Q

the gill bars are separated by small bridges called

A

synapticulae

52
Q

deeply grooved structure in the floor of the pharynx

A

endostyle

53
Q

thyroid gland in amphioxus

A

endostyle

54
Q

located on the roof of the pharynx

A

epipharyngeal groove

55
Q

they protrude into the atrium from the body wall, still bounded by the atrial lining.

A

Gonads

56
Q

large, nucleated cells

A

Ovary

57
Q

smaller germ cells, which appear as a mass of small dark dots

A

Testis

58
Q

hollow oval-shaped structure seen on the right side of the pharynx

A

Hepatic diverticulum

59
Q

Present in the cross-section as three sacs

A

Coelom

60
Q

located on both sides of the epipharyngeal groove

A

Coelomic cavities

61
Q

paired dorsal aortae may be seen between the notochord and the dorsal end of each of the paired coelomic cavities

A

Blood vessels

62
Q

enclosed within the ventral coelomic cavity

A

Ventral aorta

63
Q

present close to the midpoint of the medical borders of the gonads

A

Cardinal Veins

64
Q

large hollow oval structure lying ventral to the unpaired dorsal aorta

A

Intestine

65
Q

Beneath the intestine

A

Subintestinal Vein

66
Q

seen at levels posterior to the atriopore; at levels anterior to the atriopore, metapleural folds will be seen in its place

A

Central fin

67
Q

rather than dorsal or ventral fins, it is present. It is narrower and higher than either.

A

Caudal fin

COMPARATIVE ANATOMY (2 decks)

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