Anatomy of Dogfish Shark Flashcards

1
Q

The dogfish shark is also known as

A

Spiny dogfish

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2
Q

The dogfish shark belongs to the superclass Piesces because of this 3 characteristics

A
  • Presence of scales
  • Presence of gills
  • Paired appendages in the form of fins
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3
Q

Its cartilaginous skeleton makes it a member of which class

A

Chondrichthyes

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4
Q

Animals belonging in class Chondrichthyes

A

Sharks, skates, rays, chimera

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5
Q

Because its gill slits open separately to the outside it belongs to what subclass?

A

Elasmobranchii

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6
Q

Adult males of spiny dogfish length

A

2-3 feet in length

females are slightly larger
some large sharks are more than 30 ft in length

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7
Q

Dogfish shark prefer what temperature

A

About 10 degrees Centigrade

note: they migrate north in the spring
south in the fall

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8
Q

2 dogfish shark species

A

Squalus acanthias- found in the North Atlantic coast
Squalus suckleyi- abounds along the Pacific coast

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9
Q

To remember:

A

Their carnivorous and predacious habits are responsible for the annual destruction of large numbers of commercially valuable fish, they also destroy fishing nets

Their usefulness is for laboratory study

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10
Q

3 reasons why dogfish are studied

A
  1. Exhibits the organizational pattern of the vertebrate body in almost a generalized condition
  2. It is easily dissected because its skeleton is entirely cartilaginous
  3. Because of its size , this allows as complex structures as the brain , the spinal cord, cranial nerves, inner ear, and the eye muscle to be disclosed with ease
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11
Q

European counterpart

A

Scyllium

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12
Q

Smooth dogfish

A

Mustelus

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13
Q

The rough sandpaper quality of the skin surface is due to the presence of ?

A

Placoid scales embedded on it

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14
Q

Each scale is consists of a diamond- shaped, bony _____

A

Basal plate

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15
Q

Basal plate is embedded in __

A

Stratum laxum of the dermis

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16
Q

Projecting caudally above the epidermis surface

A

Constricted neck and a spine

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17
Q

The base is anchored to the ____

A

Stratum compactum by fibers

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18
Q

A centrally placed _____ is present within the spine

A

Pulp cavity

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19
Q

The cavity is contain of

A

Blood vessels that nourish the dentine that makes up the bulk of the spine

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20
Q

What substance protects the exposed surface of the spine

A

Enamel-like substance

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21
Q

The skin consists of two major layers

A

Epidermis (thin outer)
Dermis (thick inner)

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22
Q

The epidermis of what kind of tissue

A

Stratified epithelium which are flat

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23
Q

The cells of the basal layer is ___

A

Stratum germinativum - columnar cells - mitotically active - responsible for the formation of the entire epidermis

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24
Q

Numerous unicellular, mucus- secreting cells are distributed along the surface between what elements

A

Squamous Epithelial elements

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24
Q

Loose connective tissue

A

Stratum laxum

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25
Q

Denser connective tissue

A

Stratum compactum

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26
Q

Small pigment cells are called

A

Melanophores

27
Q

Responsible for the gray color of the dorsal and lateral surfaces of the dogfish’s body

A

Melanophores

Note: they are absent from the lighter ventral surfaceand also from localized areas so this results to white spors

28
Q

Broad and somewhat flattened

A

Head

29
Q

Fusiform in shape, in order to facilitate locomotion this gradually tapers posteriorly

A

Trunk

30
Q

Compressed laterally and becomes a caudal fin, it is also the principal organ of locomotion

A

Tail

31
Q

Five pair of oblique openings, located on the sides of the head, communicates with the pharynx

A

External gill slits

32
Q

Means gill plate refers to the plate of skin between external openings of each of the gill slits

A

elasmobranch

33
Q

Modified first gill slits located above and behind the eye

A

spiracle

34
Q

Serves for water intake, especially when the jaws are grasping food

A

spiracle

35
Q

Located laterally near the top of the head, they cannot simultaneously focused on a single object, the eyelids are immovable

A

Eyes

36
Q

The linearly arranged series of minute openings, on each side the line extends from a point just behind the spiracle to the tail

A

Lateral line canal

37
Q

Thought to serve as a receptor for low-frequency vibrations and hydrostatic pressure changes

A

Lateral line canal

38
Q

Pair of flexible appendages located ventrolaterally behind the gill slits, they have short bases and are connected by a ventral cartilaginous bar

A

Pectoral fins

39
Q

Pair of flexible appendages located ventrolaterally at the caudal end of the trunk. They are smaller than the pectoral fins

A

Pelvic fins

40
Q

Two unpaired appendages located along the dorsomedian line, one somewhat behind the level of the pectoral find, the other somewhat behind the level of the pelvic fin

A

Dorsal fin

41
Q

Located at the anterior border of each dorsal fin, they are sharp and posteriorly directed any may be considered modified scales

A

Fin spines

42
Q

The presence of fin spines is reflected in the species name

A

acanthias (Greek akantha, thorn)

43
Q

Major part of the tail, consisting of a large dorsal lobe and a smaller ventral kive

A

Caudal fin

44
Q

This type of tail in which the lobes are unequal in size is called

A

Heterocercal

45
Q

Openings situated on the ventral surface of the snout

A

External nares

46
Q

Oval and is thought to have an incurrent function

A

Medial aperture

47
Q

Round and is presumed to be the excurrent orifice

A

Lateral aperture

48
Q

Rather than communicating with the pharynx, the nares end blindly and thus serve only as?

A

Olfactory organs

49
Q

Located subterminally, a feature characteristics of elasmobranchs

A

Mouth

50
Q

Blind pocket located at each corner of the mouth

A

Labial pouch

51
Q

Furrow extending forward from each labial pouch

A

Labial groove

52
Q

These structures, thought to be modified placoid scales, are arranged in series of rows paralleling the curvature of the jaws

A

Teeth

53
Q

The first two rows of teeth, located on the crest of each jaw

A

Functional teeth- flat sharped edge and tend to be three pointed- serve to hold and tear food rather than to chew it

54
Q

Two small openings located on the dorsal surface of the head between the spiracles

A

Endolymphatic pores

55
Q

They are the external openings of the endolymphatic ducts which extend up from the internal ear

A

Endolymphatic pores

56
Q

Numerous tint pores in the skin of the top and bottom of the head, their presence can be observed by pressing the skin surface and noting the sites from which oozes

A

Ampullae of Lorenzini

57
Q

Special endings that serve as thermoreceptors and sometimes mechanoreceptors, these endings are innervated by fibers from the seventh cranial nerves

A

Ampullae of Lorenzini

58
Q

Modified copulatory organs located at the median border of each pelvic fin in the adult male of the dogfish

A

Claspers

59
Q

Takes form of elongated projections that are indented on one side by a deep groove

A

Claspers

60
Q

A region located posteriorly on the ventral surface of the body that serves as a common exit for terminal products of the digestive, urinary and reproductive systems

A

Cloaca

61
Q

A cone shaped structure possessing a pore as its apex that projects from the roof of the cloaca

A

Papilla

62
Q

Both urine and sperm are emitted through the pore

A

Urogenital Papilla

63
Q

The pore is associated with the elimination of urine only

A

Female urinary papilla

64
Q

Openings that are located posteriorly on the lateral edge of the cloaca of both sexes and the function is unknown

A

Abdominal pores