L21 - Bony Fish

Question 1

How many extant species of fish are their?

Answer 1

35,400

Question 2

What are the two class of the superclass Agnatha?

Answer 2

Cephalaspidomorphi & Myxini

Question 3

What is the order of the class Cephalaspidomorphi?

Answer 3

Petromyzontiformes: lampreys (48 extant spp)

Question 4

What is the order of the class Myxini?

Answer 4

Myxiniformes: hagfish (88 extant spp)

Question 5

What are the two sub-class of the class Chondrichthyes?

Answer 5

Elasmobranchii & Holocephali

Question 6

What is the sub-class Elasmobranchii?

Answer 6

Sharks, skates, rays (1,279 extant spp)

Question 7

What is the sub-class Holocephali?

Answer 7

Chimaeras (55 extant spp)

Question 8

What are the class of the superclass Osteichthyes?

Answer 8

Sarcopterygii & Actinopterygii

Question 9

What is the class Sarcopterygii?

Answer 9

Lobe-finned fish (8 extant spp)

Question 10

What are the subclass of the class Sarcopterygii?

Answer 10

Actinistia: coelacanths (2 spp)
Dipnomorpha: lungfish (6 spp)

Question 11

What is the class Actinopterygii?

Answer 11

Ray-finned fish (33,969 extant spp)

Question 12

What is the subclass of the class actinopterygii?

Answer 12

Chondrostei: sturgeons, paddlefish (52 extant spp)

Question 13

What are the infraclass of the subclass Chondrostei?

Answer 13

Holostei: bowfins, gars (8 spp), Teleostei: Teleosts; 96% of all living fish

Question 14

How many orders and families in the superclass Osteichthyes?

Answer 14

> 50 orders, >500 families.

Question 15

How do most teleosts feed?

Answer 15

Most teleosts suction feed.

Question 16

Buoyancy in Osteichthyes?

Answer 16

Neutral buoyancy, much lower cost of transport, new niches

Question 17

What is specific gravity?

Answer 17

Specific gravity is the ratio of the density of a substance to the density of distilled water. Unit = g ml-1. Freshwater 1.00, seawater 1.026, fish muscle 1.050, cartilage 1.100, bone 2.000, average lipid 0.900, air (at 20 degC) 0.001204.

Question 18

What are the advantages of using gas as a buoyancy aid?

Answer 18

Gas is >800-times less dense than lipid; much less is required for neutral buoyancy. Without buoyancy: 7% denser than freshwater, 5% denser than seawater. Only requires 5-7% increase in volume. Quantity of gas can be adjusted quickly so able to compensate for short-term changes.

Question 19

What are physostomatous fish?

Answer 19

Pneumatic duct between swimbladder and gut open throughout life (lower teleosts, e.g. clupeids, anguilla).

Question 20

What are physoclistous fish?

Answer 20

Pneumatic duct closes early in development (higher teleosts)

Question 21

What opens up a multitude of life styles?

Answer 21

Short deep body best for manoeuvrability, but produces high drag when swimming

Question 22

What is the ideal shape for continuous swimming?

Answer 22

Fusiform (spindle shaped). E.g. scombrids (mackerels, tunas, etc)

Question 23

What increases linearly with depth?

Answer 23

Pressure (atm)

Question 24

What are particularly affected by pressure?

Answer 24

Gases

Question 25

How does the swim bladder change on descent?

Answer 25

It compresses, fish becomes negatively buoyant. To maintain neutral buoyancy: more gas into gas-bladder.

Question 26

How does the swim bladder change on ascent?

Answer 26

It expands, fish becomes positively buoyant. To maintain neutral buoyancy: expel gas from gas-bladder.

Question 27

What are the adaptations for buoyancy in deep-sea fish?

Answer 27

Quanity and speed of gas secretion into swim bladder depends on the size of capillary bed, so many deep sea fish have multiple gas glands. Deep water fish tend to have larger oval per volume of swim bladder. Lightly ossified skeleton, few if any scales, reduced musculature (important if weak bones), loss of swimbladder entirely.

Question 28

How does tissue change after being pulled up?

Answer 28

Extreme tissue damage from being pulled up.

Question 29

How do teleosts reproduce?

Answer 29

Most are broadcast spawners, unique to aquatic animals, high fecundity of small eggs - gametes released into water column for external fertilisation without mate selection. Attrition: far more zygotes produced than will ever reach maturity - mortality rates of over 99.99%

Question 30

What are the vast majority of fish?

Answer 30

All elasmobranchs are predatory except for 13 species of filter feeders. Large, terminal mouths with well developed biting or grasping teeth.

Question 31

What are grazers and browsers?

Answer 31

Many with specialised morphologies and therefore narrow diets width (e.g. butterfly fish); others may be more generalist. Grazers may be herbivorous (cichlids, blennies damselfish) but true herbivory is quite rare in fish. Some grazers may be carnivorous, e.g. some catfish and cichlids browse on scales and mucous of other fish. Some grazers are omnivorous, e.g. parrotfish browse coral, seagrass, algae.

Question 32

What are strainers/filter feeders?

Answer 32

Often large, toothless mouths, long gill rakers, food selection by particle size.

Question 33

What are bottom feeders?

Answer 33

Mostly bottom feeding fish sucking food/detritus into mouth and ejecting non-digestible items. Grey mullets scrape mud in estuaries. Sturgeons hoover river/sea bed.

Question 34

What is an example of symbioses?

Answer 34

Cleaner fish remove dead and damaged tissue/scales and parasites. Often have characteristic colouration and set up cleaner stations where fish in search of cleaning will adopt stereotypical poses to ilicit cleaning. Some species are obligate cleaners. Many other species show facultative cleaning behaviour as juveniles (butterfly fish, angelfish).

Question 35

What are the clupeiformes?

Answer 35

5 of the top 14 fished species/genera in 2020 (including 4 in the top 10 and the number one spot: Engraulis ringens). 15% of all fish biomass, 10072000 tonnes.

Question 36

What are the Scombridae?

Answer 36

4 of the top 14 fished species/genera in 2020 (including the number three spot, Katsuwonus pelamis). 10% of all fish biomass, 6805000 tonnes

Question 37

What are the Gadiformes?

Answer 37

3 of the top 14 fished species/genera in 2016 (including the number two spot: Gadus chalcogrammus). 9% of all fish biomass, 6109000 tonnes.

Question 38

What are the four different types of fisheries?

Answer 38

Capture fisheries - Marine or inland waters Aquaculture - marine or inland waters

Question 39

What are the Cyprinidae?

Answer 39

9 of the top 15 inland aquacultured species/groups in 2020 were cyprinids, (including the number one and two spots). 28 726 500 tonnes, representing 58% of all finfish aqua culture in 2020 (by biomass).