Fish comparative anatomy

Question 1

What are the 3 classes of fish?

Answer 1

Class agnatha (cartilaginous skeleton)

Class chondrichtyes (cartilaginous fishes)

Class Osteichthyes (bony fishes)

Question 2

Body shape of fish characteristics?

Answer 2

• Torpedo shaped tapering towards tail
  
  • tail is main source of propulsion

Question 3

Skin of skin: what are the 3 glands of the skin of fish?

Answer 3

• Epidermis non-keratinised stratified squamous
• Glands:
  
  • mucous glands (cleaning)
  • club cells (warning chemicals)
    
    • poison glands (modified mucous glands)

Question 4

What are some important features of the skin that result in skin damage/no bleeding/disease?

Answer 4

• Non keratinised (Easily damaged)
• epidermis lacks blood vessels - BV are in the dermis, so won’t bleed if damaged
• skin susceptible to disease (bacterial, fungal, viral, parasitic)

Question 5

Skin/Integument:

• Three types of chromatophores (colours)

Answer 5

• Melanophores = black
• xanthophores = yellow
• erythrophores = red

Question 6

What controls the change in colour and pattern in skin of fish

Answer 6

• Density and dispersion of pigments
• endocrine and nervous control this
• camouflage, breeding, territorial purposes

Question 7

What are iridophores in skin of fish

Answer 7

• crystalline guianine platelets
• reflect and refract light (shimmering)

Question 8

What are the 2 types of scales in fish? **

Answer 8

• Placoid: dentine, enamel and projects/penetrates through the epidermis**
  
  • like a ‘tooth’
• teleost: consist ONLY of lamellar bone (no dentine or enamel)
  
  • develops in the dermis but DOESN’T penetrate through the epidermis

Question 9

2 components of the fish skull are:

Answer 9

• Neurocranium: olfactory, optic and otic parts of brain
• Branchiocranium: jaws, hyoid, operculum and gill arches

Question 10

Axial skeleton: characteristics of the vertebrae of this skeleton:

Answer 10

• Trunk and caudal regions
• neural arch: spinal cord
• haemal arch: blood vessels caudally

Question 11

Axial skeleton: what are splint bones?

Answer 11

• pin bones
• false ribs
  
  • in myosepta

Question 12

Appendicular skeleton and fins: what are the pectoral and pelvic fins support by?

Answer 12

• pectoral fins supported by pectoral girdle (attached to skull)
• pelvic fins supported by pelvic girdle (articulates with pectoral girdle)

Question 13

Two types of find in appendicular skeletons?

Answer 13

• Median: along the median axis. Dorsal, caudal and anal fins.
• Paired: pectoral and pelvic fins

Question 14

Characteristics of spines and soft rays (differences)

Answer 14

• Spines: hard, stout rays. single median element
• soft rays: bilateral structure, segmentation and branching

Question 15

skeletal musculature segmented: what is it segmented into (2 main things)

Answer 15

• myosepta: connective tissue/pale lines in the fish
• myomeres: muscle blocks, W shapes and considerable overlap between them (sit on top of each other)

Question 16

Musculature in locomotion: what causes locomotion in fish

Answer 16

• Propulsive forces generated by axial musculature
• alternating contractions of myomeres → lateral undulations, lateral thrust against water = forward propulsion

Question 17

Digestive system of fish:

Answer 17

• basic vertebrate pattern
• adaptations to different diets:
  
  • lampreys: rasped blood and tissue debris, oesophagus and intestine but not stomach
• gnathostomes: jawed fishes, herbivores, carnivorous
  
  • have oesophagus and usually have a stomach, intestine is varying length

Question 18

Oropharyngeal cavity: characteristics of fish teeth:

Answer 18

• Species variation with diet:
• Lampreys: rasp tissue, abrasive teeth
• Skates and rays: molluscs and crustacea, grinding molariform teeth
• parrot fish: algae growing on coral, beak and titurition with pharyngeal teet
• Sharks: kill prey, teeth continually replaced

Question 18

Oropharyngeal cavity: characteristics of fish teeth:

Answer 18

• Species variation with diet:
• Lampreys: rasp tissue, abrasive teeth
• Skates and rays: molluscs and crustacea, grinding molariform teeth
• parrot fish: algae growing on coral, beak and titurition with pharyngeal teet
• Sharks: kill prey, teeth continually replaced

Question 19

Digestive system in fish: alimentary canal; what are the features of the oesophagus

Answer 19

• oesophagus: distensible, ciliated in lampreys

Question 20

Features of the stomach in fish

Answer 20

• stomach: elongate in predatory fish: gastric glands HCL and pepsinogen
• Sac-shaped in omnivores - muscularised in the mullet
• absent in lampreys

Question 21

fFeatures of the intestine of fishes: comparison between herbivores and carnivores

Answer 21

• short in carnivores
• elongated with folds in herbivores (plant material difficult to digest)
• spiral valve in sharks
• glands for digestive enzymes and mucous

Question 22

Define pyloric caeca in fish and what is the role of it?

Answer 22

• junction of stomach and the duodenum
• digestion and absorption

Question 23

Digestive system of fish: what is the role of the liver

Answer 23

• produces bile salts
  
  • may be stored in gall bladder

Question 24

Digestive system in fish: components of the pancreas

Answer 24

• endocrine and exocrine pancreas
• may be discrete or scattered throughout the liver and omentum (hepatopancreas)

Question 25

The circulatory system of fish: what is a single circulatory system?

Answer 25

• It is one big loop, no separate systemic and pulmonary circulations
• deoxygenated blood returned from body to the heart → heart to gills → gills to the body