Fishes

Question 1

Fishes are in what Phylum?

Answer 1

Phylum Chordata

Question 2

What are Superclass Agnatha

Answer 2

jawless fishes

Question 3

What are the 2 class of Superclass Agnatha?

Answer 3

Class Myxini - hagfishes
Class Petromyzontida - lampreys

Question 4

Characteristics of Class Myxini (hagfishes)

Answer 4

-No scales or jaws – have keratinized plates
-Poorly developed eyes
-Slime glands
-Fibrous and cartilaginous skeleton
-Notochord persistent
-Vertebrae reduced or absent

Question 5

Describe circulatory system of class Myxini

Answer 5

-Low pressure circulatory system with three accessory hearts
-Single circulatory system; main heart with sinus venosus, atrium, ventricle

Question 6

Characteristics of Class Petromyzontida (Lampreys)

Answer 6

-No scales or jaws
-No paired appendages
-Moderately developed eyes
-Fibrous cartilaginous skeleton
-Persistant notochord; reduced vertebrae
-No stomach; spiral folds in intestine

Question 7

Describe circulatory system of class Petromyzontida

Answer 7

-Single circulatory system; main heart with sinus venosus, atrium, ventricle
-no accessory hearts

Question 8

Which class of Agnathans have:
-Sucker-like mouth withlips (sensory and attachment)
-Epidermal teeth line mouth
-Teeth cover moveable tongue-like structure
-Salivary glands secrete anticoagulant

Answer 8

Class Petromyzontida (Lampreys)

Question 9

Explain the process of reproduction in Class Petromyzontida (Lampreys)

Question 10

What are Superclass: Gnathostomata

Answer 10

Jawed Vertebrates

Question 11

What are the 2 important events in vertebrate evolution?

Answer 11

1. Evolution of jaws
   -More efficient gill ventilation
   -Ingestion of greater variety of food sources
2. Evolution of paired appendages
   -Important to counteract roll during locomotion
   -Also used to control tilt and lateral steering when swimming

Question 12

Characteristics of Class Chondrichthyes
Superclass: Gnathostomata

Answer 12

-Biting mouthparts
-Paired appendages
-Strong swimming musculature
-Well developed sense organs
-Cartilaginous endoskeleton (no bone!)
-Phosphatized mineral tissues retained in teeth, scales, spines

Question 13

What are the 2 subclasses of Class Chondrichthyes?

Answer 13

Subclass Elasmobranchii
Subclass Holocephali

Question 14

Characteristics of Subclass Elasmobranchii

Answer 14

-Fusiform body; extensive fins
-Hetercercal tail – thrust
-Skin with dermal placoid scales that reduce friction

Question 15

Reproduction and Development
of Subclass Elasmobranchii

Answer 15

-Male with modified pelvic fins = claspers
-Internal fertilization
-Various developmental modes (Oviparous, Ovoviviparous, Viviparous)

Question 16

Defensive modifications of Subclass Elasmobranchii

Answer 16

Tail → defensive lash
Placoid scale remnants → venomous spine

Question 17

Class Chondrichthyes
Subclass Holocephali Characteristics

Answer 17

-Large head, small mouth surrounded by large lips
-This group has specializations not found in other elasmobranchs:
-Gill cover (operculum)
-Teeth modified into large plates for crushing
-Lack scales

Question 18

What are Osteichthyes?

Answer 18

Bony Fishes and Tetrapods

Question 19

What characteristics links bony fishes and tetrapods?

Answer 19

-Endochondral bone
-Cranial/dental characters
-Lungs or swim bladder

Question 20

What are the 2 classes of Osteichthyes?

Answer 20

Class Sarcopterygii – lobe-finned fishes
Class Actinopterygii – ray-finned fishes

Question 21

Describe Class Sarcopterygii

Answer 21

-muscular lobes associated with fins
-use lungs for gas exchange
-live in areas where seasonal droughts common

Question 22

Class Actinopterygii gave rise to what 3 groups?

Answer 22

1. Clade Cladistia
2. Chondrosteans
3. Neopterygians

Question 23

Describe Class Actinopterygii

Answer 23

-Over 31,000 species
-Paleoniscids (heterocercal tail, ganoid scales)

Question 24

Which group of Class Actinopterygii is similar to paleoniscids?

Answer 24

Clade Cladistia

Question 25

Which group of Class Actinopterygii is: -Ancestral forms with bony skeleton -Modern forms have: cartilaginous skeletons, tail with upper lobe -Most live in sea; migrate to rivers to breed

Answer 25

Chondrosteans

Question 26

Describe Neopterygians

Answer 26

-Modern bony fishes -Diverged from ancient marine actinopterygians -Underwent huge evolutionary diversification

Question 27

What morphological trends that supported great diversification of the Teleost?

Answer 27

Flexible cycloid and ctenoid scales Homocercal tail – speed Flexible fins and other fin modifications Fine control of gases in swim bladder Suction feeding Pharyngeal jaws – chewing, crushing, grinding

Question 28

Why are fishes one of the most successful and diverse vertebrate groups?

Answer 28

Have been able to adapt to very demanding environment (aquatic) 1. Locomotion 2. Respiratory system 3. Highly efficient sensory systems 4. Efficient reproduction

Question 29

Mechanisms for reducing friction

Answer 29

Streamlined shape Mucoid secretions (lubricate body)

Question 30

Buoyancy Fishes can float due to one or more of four ways

Answer 30

Low density compounds incorporated into tissues (oily livers; squalene) Fins provide lift (pectoral fins or upper lobe of caudal fin) Reduction of heavy tissues in body Less dense bones/cartilaginous skeletons Swim bladder Controls volume of gas within

Question 31

How does gas get into swim bladder?

Answer 31

Gas gland  lactic acid  localized acidity of blood in rete mirabile  hemoglobin releases O2 load  counter-current multiplier  high O2 in gas gland  diffusion into swim bladder

Question 32

How fishes achieve neutral buoyancy?

Answer 32

displace additional water by a volume of gas in swim bladder Can then remove gas in swim bladder via Pneumatic duct (ancestral physostomous condition) or Ovale (derived physoclistous condition)

Question 33

Fish Circulation and its disadvantage

Answer 33

Single circuit circulation Disadvantage: gill capillaries give high resistance so blood pressure to body tissues is low

Question 34

Explain gas exchange in fish

Answer 34

Pumping action by operculum helps move water through gills (continuous flow) Water pumped into mouth and pharynx → over gills → out gill openings

Question 35

Explain Sensory Functions of fish

Answer 35

Have specialized receptors for olfaction, vision, hearing, equilibrium and balance and detecting water movements

Question 36

unique to fishes and used to detect water currents or predators/prey causing water movements

Answer 36

Lateral line system

Question 37

sensory pits in epidermis of skin connecting to canals running just below epidermis

Answer 37

Lateral line system

Question 38

Describe Reproduction and Development of Fish

Answer 38

Most fish are: Dioecious External fertilization Oviparous Eggs develop outside female from stored yolk