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Flashcards in Lab 1 Deck (83):
1

Define allometric growth

Changes in body proportions during maturation

2

Total length

Straight-line distance from most anterior point of the fish to the tip of the caudal fin

3

Standard length

Most anterior tip of fish to end of vertebral column at base of caudal fin

4

Hypural plate

Internal structure in teleosts marking the end of the vertebral column

5

How to find hypural plate

Bend caudal fin laterally near the base - crease marks end of vertebral column

6

Snout-vent length

Distance from tip of snout to opening of anus

7

Fork length

Distance from most anterior tip of fish to middle of the fork of the caudal fin
Can only be measured where the caudal fin has a distinct fork or indentation

8

Head length

Distance from most anterior point of fish to the most posterior extension of operculum
Includes any membranous flap on operculum
In skates, rays and sharks goes to base of the most posterior gill slit

9

Maximum depth of body

Maximum vertical height of body not including fins
Located about 1/3 of the length from snout in active swimmers, such as the perch

10

Minimum depth of caudal peduncle

Minimum vertical height of trunk region between posterior insertion of anal fin and caudal fin

11

Three types of fin rays

Spiny
Heavy spinous
Soft

12

Features of spiny rays

Usually stiff and sharp (but not always)
Unsegmented + unbranched

13

Features of spinous rays

Stiff + often have sharp barbs on posterior edge (eg in catfish)
Not true spiny rays but thickened, hardened soft rays

14

Features of soft rays

Usually branched and clearly segmented
Usually occur on posterior portion of a fin behind spinous rays

15

Cleithrum

Shoulder girdle

16

External nares

Nostrils
Not connected to oral cavity - blind-ended sacs
Sensory organs ONLY

17

Protective layer on outside of eye

Cornea

18

Specialised cells in the retina

Rods + cones

19

Caniniform

Pointed, elongated teeth

20

Incisoriform

Blade-like teeth
Sharp, cutting edge with broad base

21

Molaiform

Blunt, flattened teeth
For grinding + crushing

22

Cirri

Small, fleshy projections from fish head
Chemosensory (taste) or mechanosensry function
Not present in all fishes

23

Branchiostegal rays

Parallel, bony struts arranged like ribs of bellow or a fan
Connect membrane of skin below and between the two sides of the lower jaw or mandible
Stretch -> expand buccal cavity -> draw in water
Support gill membranes

24

Isthmus

Skin connecting two sides of lower jaw on ventral side of head

25

Classification of gill membranes

Free or separate - not joined to isthmus or to each other
United - joined to each other across, but not to, the isthmus
Joined to the isthmus

26

Barbels

Fleshy, hair-like projections on the chin or around the mouth
Chemosensory or mechanosensory function
Cods, catfishes + sturgeons

27

Finlets

Numerous small, flag-like projections between main dorsal fins and caudal fin or anal fin
Present in fast swimming fish such as tuna

28

Function of anal fin

Stabiliser to prevent roll
Usually absent from bottom dwelling species

29

Heterocercal tail

Upper lobe of caudal fin is larger
Posterior end of vertebral column extends into upper lobe of caudal fin

30

Homocercal tail

Symmetrical

31

Neuromasts

Specialised sense organs in lateral line system
Nerve endings are sensitive to subtle changes in pressure in the water
Usually more concentrated at head end of lateral line

32

Ctenoid scales

Common in fishes with at least one spiny ray in the dorsal fin
Common in flatfishes such as halibut and flounders on their uppermost surface
Comb-like projections (ctenii) on exposed edge of scales

33

Placoid scales

Sometimes called dermal denticles
Characteristic of Chondrichthyes
Unlayered, tooth-like scales

34

Ganoid scales

Heavy + plate-like
Form a bony armour

35

Cycloid scales

Thin + round
Flat overlapping scales
In most soft-rayed fishes

36

Ctenii

Comb-like projections on exposed edge of ctenoid scales

37

Circuli

Growth rings in fish that have seasonal variations in growth
Faster growth -> rings further apart

38

Axial muscles

Make up most of the mass of the trunk

39

Myomeres

Form W-shaped blocks in axial muscles

40

Electroplaques

Arrangement of axial muscles in fish that are able to produce electric current
Insulating layers between muscles + skin -> act like a storage battery to accumulate electrical charge

41

Physostomous condition

Fish that have a duct connecting the swim bladder to the mouth in bony fish
Ancestral
Used to breathe atmospheric air during periods of drought

42

Physoclistous condition

Fish that do not have a duct connecting the swim bladder to the mouth
More advanced bony fish

43

Pyloric ceca

Blunt-ended finger-like projections extending into the stomach
Over 100 in salmonids
Increase absorptive surface area of stomach

44

Mesentery

Surrounds the intestine
May contain yellow-orange fat deposits

45

Function of spleen

Produces new blood cells and destroys old ones

46

Function of reproductive ducts

Conduct gametes from gonads to outside for fertilisation

47

Function of cerebral hemispheres of forebrain

Sense of smell

48

Cerebellum

Hindbrain

49

Function of the cerebellum

Co-ordinates muscular movement and adjusts spatial equilibrium
Integrates info from lateral line + inner eat

50

Elongated body form

Fusiform

51

Anguilliform

Eel-like
Greatly elongated

52

Ovate body form

Truncated
Shortened

53

Compressiform

Thin, narrow, deep
Eg. angel fish

54

Depressiform

Flattened

55

Globiform

Subcircular
Hemispherical
Eg. pufferfish

56

Holobranch

Bony gill arch supporting gill filaments
Four on each side of gill cavity in most fish

57

Hemibranch

Reduced gill arch
Attached to underside of operculum

58

Gill rakers

Extensions of gill arches
Project inwards
Prevent food particles passing out with flow of respiratory water

59

Agnathans

Jawless fishes

60

Ostracoderms

500 million years ago (Cambrian period)
Jawless fishes
Successful for 100 million years

61

Surviving ostracoderms today

Lampreys + hagfishes

62

Differences between hagfish and lampreys

Hagfish have single nostril opening into the mouth, lampreys do not
Lampreys have well developed eyes, hagfishes do not
Lampreys have well-developed lateral line system, hagfish do not

63

Ammocoetes

Filter-feeding larval stage of lampreys

64

Lamprey teeth

Made of keratin
Derived from the skin

65

Which (hagfish or lampreys) have dorsal fins?

Lampreys

66

Which (hagfish or lampreys) have pre-anal fins?

Hagfish

67

Origin of the jaw

Hinged gill supports modified for improved feeding efficiency

68

Number of dorsal fins in sharks

Never more than two

69

Most sharks have ___ gill slits

5 but can have 6 or 7

70

Function of spiracles in sharks

Accessory water intake when mouth is feeding

71

Carchariniformes

Largest order of sharks
Hammerheads, requiem sharks, blue sharks and cat sharks

72

Rajiformes

Rays and skates

73

What order do rays and skates belong to?

Rajiformes

74

Position of gill openings on a skate

Ventral

75

The anterior edge of skate's pectoral fin is attached to...

Side of the head

76

The sting on an electric ray is a modified...

Caudal muscle

77

Basking shark feeding method

Filter feeder
Traps plankton in gill rakers

78

Differences between skates and rays

Skates are oviparous (lay eggs), rays are viviparous (live births)
Skates have distinct dorsal fins, rays have lost or is vestigial
Skates pelvic fin is divided into two lobes, rays have just one
Skates have a fleshy tail, rays have a whip=like tail with 1-2 stinging spines
Skates are usually smaller
Rays usually inhabit shallower water (although not always)

79

Holocephali

Chimaeras + ratfish
First definitive fossils from Jurassic period 200 million years ago but could be much earlier
Cartilaginous skeleton + internal fertilisation

80

Autostylic jaw suspension

Upper jaw is connected directly to cranium, lower jaw is directly attached

81

Protection for gills in chimaeras

Calcified opercular plate
Not present in any other fish

82

Ampullae of Lorenzini

Sensing organs - jelly-filled pores
Electroreceptors
Common in sharks, rays + chimaeras

83

Function of head clasper in male ratfish

Stimulate female during courtship