Fish Morphology and Anatomy

Question 1

Why is fish body shape closely linked to their phylogeny and lifestyle?

Answer 1

Fish body shape reflects both evolutionary lineage and adaptations to specific lifestyles, allowing basic categorization for descriptive purposes.

Question 2

Describe the compressed body shape and its typical habitat.

Answer 2

Laterally compressed, appearing thin when viewed head-on. Common in reef-associated fishes.

Question 3

What is a depressed body shape, and which habitats are associated with it?

Answer 3

Dorso-ventrally flattened (e.g., flatfish or skates). Often linked to benthic habitats, though some, like mobulid rays, are pelagic.

Question 4

What defines a globiform body shape, and where is it commonly found?

Answer 4

Rounded body, often in deep-sea fishes, suited for energy-efficient ambush hunting in mesopelagic or benthopelagic zones.

Question 5

Explain the anguilliform body shape and its associated swimming style.

Answer 5

Elongate and tubular, seen in eels. Propulsion relies on sinuous body movements rather than fins.

Question 6

What characterizes a fusiform body shape, and which fishes typically have it?

Answer 6

Bullet-shaped, tapering at both ends (e.g., tuna, mackerel). Typical of active pelagic predators, minimizing inertial drag.

Question 7

What is the aspect ratio in caudal fins, and why is it important?

Answer 7

The ratio of fin height to surface area. It indicates swimming performance and metabolic rate.

Question 8

Describe the characteristics and advantages of rounded caudal fins.

Answer 8

High surface area and low aspect ratio. Flexible and used by fish relying on pectoral fins for propulsion.

Question 9

What are the features of lunate caudal fins, and which fishes possess them?

Answer 9

Small surface area and high aspect ratio. Found in fast swimmers like tuna and mackerel, enabling efficient propulsion.

Question 10

How do heterocercal tails benefit certain fish like sharks?

Answer 10

The longer upper lobe helps balance lift forces while swimming.

Question 11

How does caudal fin shape relate to swimming speed and metabolic cost?

Answer 11

Streamlined shapes (e.g., fusiform body, lunate fins) minimize drag and metabolic cost, favoring high-speed movement.

Question 12

Why is water a challenging medium for fish locomotion?

Answer 12

Water is 800 times denser and 50 times more viscous than air, increasing drag and metabolic costs.

Question 13

Differentiate between viscous and inertial drag in fish movement.

Answer 13

• Viscous drag: Friction between fish surface and water, influenced by surface smoothness and area.

Inertial drag: Resistance due to water displacement, increasing with speed and reduced by streamlining.

Question 14

How do fish minimize viscous drag?

Answer 14

Through smooth scales, surface mucus, and streamlined bodies.

Question 15

What adaptations help fast-moving pelagic fishes reduce inertial drag?

Answer 15

Circular cross-section, 25% body width-to-length ratio, and fusiform shape with propulsion from the caudal fin.

Question 16

Why must fish swallow prey whole or take bites?

Answer 16

They cannot manipulate prey, so most are larger than their prey to capture it effectively.

Question 17

List common prey capture methods in fish.

Answer 17

• Active pursuit (e.g., tuna, salmon)

Ambush (e.g., anglerfish, pike)

Filter feeding (e.g., whale sharks)

Scavenging (e.g., deep benthic fishes)

Suction feeding (e.g., lionfish)

Herbivory (e.g., parrotfish)

Question 18

How does skull morphology influence feeding strategies in fish?

Answer 18

Flexible, diverse skulls enable adaptations like precision for small prey or large mouths for bigger prey.

Question 19

What role does the axial skeleton play in fishes?

Answer 19

Protects the dorsal nerve cord, resists shortening during muscle contractions, and allows flexibility.

Question 20

Describe the integument (skin) and its functions in fish.

Answer 20

Maintains shape, protects against infection and damage, aids in communication, and enables gas exchange and ion regulation.

Question 21

Why is vision significant in deep-sea fishes with no sunlight?

Answer 21

Vision aids in detecting bioluminescence and navigating dark environments, despite physiological costs.

Question 22

How do otoliths contribute to fish hearing and fisheries science?

Answer 22

Otoliths detect sound vibrations and show growth rings for aging fish, fundamental in fisheries management.

Question 23

What is the lateral line system, and how does it aid fish movement?

Answer 23

Specialized cells (neuromasts) detect water currents and turbulence, critical for spatial awareness.

Question 24

How does electroreception function in fish like sharks?

Answer 24

Ampullary receptors detect electrical currents from prey muscle contractions, especially in saline environments.

Question 25

Provide species examples for each caudal fin shape.

Answer 25

• Rounded: Anglerfish
• Lunate: Tuna, Mackerel
• Heterocercal: Sharks

Question 26

How does inertial drag influence fish morphology?

Answer 26

Increases with speed; streamlined bodies with circular cross-sections and fusiform shapes minimize this drag.

Question 27

What adaptations in the dermis aid in camouflage and survival?

Answer 27

Pigmentation for coloration, embedded scales for protection, and connective tissue for mechanical support.

Question 28

How do neuromasts in the lateral line system function?

Answer 28

Superficial neuromasts detect slow currents; canal neuromasts sense turbulent, fast-moving water.

Question 29

What is the significance of otolith diversity in fish?

Answer 29

Reflects sensory adaptations; smaller in fast-moving fish, larger and more robust in demersal species.

Question 30

Why are spherical lenses crucial for fish vision?

Answer 30

They counteract the lower refractive index difference in water, focusing light efficiently.

Question 31

Why are fish skulls flexible

Answer 31

A lot of bones
Infused bones
Bones are thin

Question 32

What mouth positions are there and what types of fishes posess them

Answer 32

Inferior/ventrally positioned - benthic feeders
Anterior mouth - pursuit predators
Terminal mouth - active hunting
Superior - surface feeders

Question 33

What are teeth types

Answer 33

Canines - sharp cone like (pikes)
Incisors - sharp edged for cutting similar to human teeth (parrotfish)
Molars - broad flat for crush (skate)
Cardiform - short packed teeth (catfish)
Villiform - long fine teeth (lion fish)
Pharyngeal teeth - teeth in throat (eels)