Fish

Question 1

What are the key features of the phylum Chordata?

Answer 1

Notochord, dorsal tubular nerve chord, postanal tail, pharyngeal slits, endostyle/thyroid gland.

Question 2

What are the three subphylums of the phylum chordata?

Answer 2

Vertebrata, Cephalochordata, and Urochordata.

Question 3

What are two hypotheses of the evolutionary origins of fish? Which is the most likely?

Answer 3

Originated from tunicates (sac-like sessile filter feeders), and originated from lancelets (amphioxus, free-living). Lancelet evolution is more likely.

Question 4

What are the two superclasses of the subphylum Vertebrata?

Answer 4

Agnatha and Gnathostomata.

Question 5

What are the three key subclasses in the superclass Agnatha?

Answer 5

Myxini (hagfish), petromyzontida (lampreys), and ostracoderms (group - extinct).

Question 6

What is the class in Agnatha?

Answer 6

Cyclostomata.

Question 7

What are the two key extinct groups in the superclass Gnathostomata?

Answer 7

Placoderms and Acanthodians.

Question 8

What are the two classes in the superclass Gnathostomata?

Answer 8

Chondrichthyes and Osteichthyes.

Question 9

What are the subclasses of Chondrichthyes - Gnathostomata?

Answer 9

Elasmobranchii (sharks and rays) and Holocephali (whole heads).

Question 10

What are the subclasses of Osteichthyes - Gnathostomata?

Answer 10

Actinopterygii (ray finned fish - most fish) and Sacropterygii (lobe-finned fish).

Question 11

What are the defining features of the Superclass Agnatha class Cyclostomata?

Answer 11

Circular mouths, teeth made of keratin, no/paired fins, poor swimmers.

Question 12

What are the key features of the extinct group Ostracoderms?

Answer 12

Mineralized bony heavy armor.

Question 13

What are the key features of the superclass Gnathostomata?

Answer 13

Jaws, paired fins.

Question 14

What are the key features of the extinct group Placoderms?

Answer 14

First jawed fish, plate skin - heavy armor around head, mostly bottom dwellers, primitive autostylic jaw with true paired fins. Heterocercal tail.

Question 15

What are the key features of the extinct group Acanthodians?

Answer 15

“Spiny sharks,” small column feeders, teeth with large head and eyes, streamlined round bodies, more lightweight armor. Heterocercal tail. Hyoid (visceral arch) - attachment between chondrocranium and the skull. Amphistyllic jaw.

Question 16

What are the key features of the Chondrichthyes subclass Elasmobranchii (sharks and rays)?

Answer 16

Spiracles, sub-terminal mouth with protrusible jaw - detached from skull, heterocercal tail, fins supported by ceratorichia, placoid scales, clasper, cloaca - joint anal and urogenital, ampullae of lorenzini.

Question 17

What are the key features of the Gnathostomata class Chondrichthyes?

Answer 17

Cartilaginous skeleton, placoid scales, separate sexes with internal fertilisation (claspers in males), 5-7 gill pairs - slits in sharks and rays, covered by operculum in chimaeras, replacement teeth, oil liver for buoyancy.

Question 18

What are placoid scales?

Answer 18

Scales that feel rough in one direction and smooth in the other.

Question 19

What’s a clasper?

Answer 19

Sexual organ modified from pelvic fin in males - used for sperm.

Question 20

What are the key features of the subclass Holocephali?

Answer 20

Chimaeras/ratfish, non-protrusible jaw - top attached to the skull, operculum, diphycercal (equal) tail, naked skin with few placoid scales, no cloaca - separate anal and urogenital opening. Grinding plates instead of teeth.

Question 21

What are the key features of the class Osteichthyes?

Answer 21

Bony fish, 96% of all living fish, true bony skeleton - endochondrial bone, scales - ganoid, cycloid, or ctenoid. Bony operculum covering gills, bony fin support (lepidotrichia), lung or swim bladders.

Question 22

What’s the operculum in Osteichthyes?

Answer 22

A bony plate covering gills - can use pressure to draw water over the gills for improved respiratory efficiency.

Question 23

What are swim bladders (lungs)?

Answer 23

Gas filled pouch branching from esophagus, efficient for neutral buoyancy and modified for air breathing in some groups.

Question 24

What are the key features of the Osteichthyes subclass Sarcopterygii?

Answer 24

Lobed fins, only eight species, heavy scales, pulmonary and systemic circulatory systems incompletely separated.

Question 25

What are the infraclasses of Sacropterygii?

Answer 25

Actinistia - lobe finned and 2 species, Dipnoi - two breathing - air and water.

Question 26

What are the infraclasses of Actinopterygii?

Answer 26

Chondrostei - cartilage bones, ganoid scales. Neopterygii - new fins - primitive.

Question 27

What are the key features of the division Teleostei in the infraclass Neopterygii?

Answer 27

"perfect bones," most diversity, bony lightweight skeleton, homocercal tail supported by uroneural bones, cycloid or ctenoid scales, moveable maxilla and premaxilla, swim bladder. - fast

Question 28

What does having a moveable maxilla and premaxilla in Teleostei do?

Answer 28

Allows for suction feeding.

Question 29

What are the main two types of swimming in fish?

Answer 29

Undulatory (primitive swimming - muscular contraction - swim via waves), and Oscillatory (wing or oar-like swimming - using an anchor as a pivot).

Question 30

What are the two types of drag in water - adaptations to counter?

Answer 30

Friction drag "stickiness," and pressure drag (pressure difference between head and tail). Streamlining + tucking in fins + mucous can reduce drag as well as breaking up pressure drag with spines and scales.

Question 31

How do fish stay afloat and move up and down in the water? What are the two different kinds?

Answer 31

Buoyancy - dynamic (moving) or static (non-moving).

Question 32

What are some examples of dynamic buoyancy?

Answer 32

Constantly moving - with pectoral fins and heterocercal tail to create lift - high energy cost.

Question 33

What are some examples of static buoyancy?

Answer 33

Swim bladder, use of oils, fats, and buoyant ions.

Question 34

What are the two different kinds of swim bladders?

Answer 34

Physostomous: gas-filled sac connected to the oesophagus. Filled with air by gulping and blood diffusion - emptied by mouth. Phytoclistous: sealed off from oesophagus, filled by blood diffusion and emptied at the end of the body.

Question 35

What are the three main muscle types for power and control in swimming?

Answer 35

Flexors/extensors, protractors/retractors, and adductors/abductors.

Question 36

What is the role of the caudal fin?

Answer 36

Propulsion and steering.

Question 37

What's the role of the dorsal and anal fins?

Answer 37

Prevent roll and helps propulsion in undulatory swimming.

Question 38

What is the role of pelvic fins?

Answer 38

Control pitch and act as hydrofoils.

Question 39

What is the role of pectoral fins?

Answer 39

Propulsion, turning, and stopping.

Question 40

What are the key characteristics of fish vision?

Answer 40

Fisheye - doomed lens, unequal photoreceptors (cones for shallow water and colour, and rods for low light).

Question 41

What are the key features of fish hearing?

Answer 41

Otoliths (ear bones) are dense, suspended in fluid move and send messages via cilia. Good for low frequency, high energy sound.

Question 42

How can the swim bladder act for sound?

Answer 42

Amplifies sound due to being air filled - sonic muscles allow vibration. Good for high frequency/low energy sound.

Question 43

What are the key features of fish smell?

Answer 43

Nares = nose. Goes in one side, out the other. Can smell pheremones, mates, homing, and chemical alarm systems.

Question 44

What are the key features of taste in fish?

Answer 44

Taste receptors in mouth, lips, skin, and fins.

Question 45

What is distant touch in fish?

Answer 45

Fish can detect touch from far away due to their lateral line (canal with neuromasts (hair cells with cupola - free or protected in canal organs)). Used for object avoidance, schooling, and prey location.

Question 46

What is electroreception in fish?

Answer 46

Can be done with specialized neuromasts with no cilia. Ampullary organs - weak, low frequency - passive electrolocation (elasmobranchii), and Tuberous organs sensitive to higher, stronger frequency - active electrolocation.