Fish Morphology and Anatomy Flashcards
Why is fish body shape closely linked to their phylogeny and lifestyle?
Fish body shape reflects both evolutionary lineage and adaptations to specific lifestyles, allowing basic categorization for descriptive purposes.
Describe the compressed body shape and its typical habitat.
Laterally compressed, appearing thin when viewed head-on. Common in reef-associated fishes.
What is a depressed body shape, and which habitats are associated with it?
Dorso-ventrally flattened (e.g., flatfish or skates). Often linked to benthic habitats, though some, like mobulid rays, are pelagic.
What defines a globiform body shape, and where is it commonly found?
Rounded body, often in deep-sea fishes, suited for energy-efficient ambush hunting in mesopelagic or benthopelagic zones.
Explain the anguilliform body shape and its associated swimming style.
Elongate and tubular, seen in eels. Propulsion relies on sinuous body movements rather than fins.
What characterizes a fusiform body shape, and which fishes typically have it?
Bullet-shaped, tapering at both ends (e.g., tuna, mackerel). Typical of active pelagic predators, minimizing inertial drag.
What is the aspect ratio in caudal fins, and why is it important?
The ratio of fin height to surface area. It indicates swimming performance and metabolic rate.
Describe the characteristics and advantages of rounded caudal fins.
High surface area and low aspect ratio. Flexible and used by fish relying on pectoral fins for propulsion.
What are the features of lunate caudal fins, and which fishes possess them?
Small surface area and high aspect ratio. Found in fast swimmers like tuna and mackerel, enabling efficient propulsion.
How do heterocercal tails benefit certain fish like sharks?
The longer upper lobe helps balance lift forces while swimming.
How does caudal fin shape relate to swimming speed and metabolic cost?
Streamlined shapes (e.g., fusiform body, lunate fins) minimize drag and metabolic cost, favoring high-speed movement.
Why is water a challenging medium for fish locomotion?
Water is 800 times denser and 50 times more viscous than air, increasing drag and metabolic costs.
Differentiate between viscous and inertial drag in fish movement.
- 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.
How do fish minimize viscous drag?
Through smooth scales, surface mucus, and streamlined bodies.
What adaptations help fast-moving pelagic fishes reduce inertial drag?
Circular cross-section, 25% body width-to-length ratio, and fusiform shape with propulsion from the caudal fin.
Why must fish swallow prey whole or take bites?
They cannot manipulate prey, so most are larger than their prey to capture it effectively.
List common prey capture methods in fish.
- 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)
How does skull morphology influence feeding strategies in fish?
Flexible, diverse skulls enable adaptations like precision for small prey or large mouths for bigger prey.
What role does the axial skeleton play in fishes?
Protects the dorsal nerve cord, resists shortening during muscle contractions, and allows flexibility.
Describe the integument (skin) and its functions in fish.
Maintains shape, protects against infection and damage, aids in communication, and enables gas exchange and ion regulation.
Why is vision significant in deep-sea fishes with no sunlight?
Vision aids in detecting bioluminescence and navigating dark environments, despite physiological costs.
How do otoliths contribute to fish hearing and fisheries science?
Otoliths detect sound vibrations and show growth rings for aging fish, fundamental in fisheries management.
What is the lateral line system, and how does it aid fish movement?
Specialized cells (neuromasts) detect water currents and turbulence, critical for spatial awareness.
How does electroreception function in fish like sharks?
Ampullary receptors detect electrical currents from prey muscle contractions, especially in saline environments.
