L4 Bevan - Bony Fish Diversity and Adaption

Question 1

What is the most advanced of the bony fish?

Answer 1

Teleosts

Question 2

How do teleosts brood their young?

Answer 2

In their mouths

Question 3

What are Otoliths an what do they do?

Answer 3

Otoliths are stony concretions situated in part of the ear system at the base of the brain

record of fish growth as they are deposited gradually through life

shape is species dependent (diagnostic)

Question 4

What are the 4 types of fish scale?

Answer 4

1. Placoid - sharks
2. Cosmoid - lungfish - composed of and inner and outer layer - cosmine and vitrodentine
3. Ganoid - bowfish and sturgeon
4. Cycloid/ctenoid - majority of teleost fish

Question 5

What is the gas bladder?

Answer 5

Gas filled sac located in the dorsal region of the body cavity.

its volume can be varied to increase or decrease buoyancy

Question 6

What are the 2 types of swim bladder?

Answer 6

1. Physostomous - (more primitive), a connection is retained between the swim bladder and the gut, allowing the fish to fill up the swim bladder by “gulping” air. Excess gas can be removed in a similar manner.

Physoclistous - connection to digestive tract is lost. Fish either have to rise to the surface to fill up their swim bladders or introduce gas (usually oxygen) to the bladder to increase its volume and thus increase buoyancy

Question 7

What are the 4 types of locomotion of fish?

Answer 7

1. Anguilliform
2. Carangiform (SUBCARANGIFORM)
3. Ostraciform
4. Swimming with fins

Question 8

What is the difference between undulation and oscillation?

Answer 8

undulation– sinusoidal wave passing down body or fins

oscillation– structure moving back and forth

Question 9

Describe anguilliform swimming

Answer 9

Involves sinusoidal undulations

Seen in most eels, dogfishes - occurs in fishes with very flexible bodies

Question 10

Describe Carangiform swimming

Answer 10

Advanced Functional hinge – connecting tail to caudal peduncle; allows fish to maintain tail at ideal attack angle of 10o to 20o throughout the power stroke

Advanced swimmers have a stiff, sickle-shaped fin; narrow and tall

HIGH ASPECT RATIO – minimal drag; ideal for sustained swimming
Reduces viscous drag by reducing surface area

Subcarangiform swimmers have caudal fins with a LOW ASPECT RATIO
Better suited for rapid acceleration and can aid hovering
Tail has intrinsic musculature to help control shape

Question 11

Describe Ostraciform swimming

Answer 11

Observed in boxfishes

is extreme in that only the tail oscillates while the body is held rigid

Contract the entire muscle mass on one side of the body then the other – produces a sculling motion

These fishes rely on armour rather than speed for protection from predators

Question 12

Describe swimming with fins

Answer 12

5 types within this group – all employ median and paired fins rather than body-tail couplings

1. Tetraodontiforms - flap their dorsal and anal fins synchronously
2. Labriform swimmers - row their pectoral fins, pushing with the broad blade then feathering it in the recovery phase (an switch to carangiform locomotion)
3. Amiiform swimmers (seahorses) the undulations pass along the dorsal fin
4. Gymnotiform undulations of a long anal fin, essentially upside down amiiform
5. Balistiform both anal and dorsal fins undulate