Swimming Flashcards
(31 cards)
What is buoyancy
An upward force exerted by a fluid that opposes the weight of an object
How is buoyancy achieved in biological organisms
By displacing a volume of water equal to their weight or using buoyancy aids like swim bladders or oily livers
How does a swim bladder aid in buoyancy
It is an internal gas-filled organ that helps fish maintain depth without swimming
Why do sharks need to keep swimming to stay afloat
They lack swim bladders and rely on oily livers
What’s the difference between CoM and center of buoyancy (CoB)
CoM is where mass is evenly distributed
CoB is the centre of displaced water volume
What condition ensures floating stability in water
When the centre of buoyancy is above the centre of mass
The 4 main forces acting on a swimming animal
Thrust
Drag
Weight
Buoyancy
What does Reynolds number represent in fluid dynamics
The ratio of intertidal forces to viscous forces, predicting flow behaviour around objects
What happens at high and low Reynolds numbers
High: inertial forces dominate
Low: viscous forces dominate
How do aquatic animals generate thrust
By accelerating a mass of water backward, relying on newtons third law
What are the 3 main mechanisms for swimming thrust generation
Body undulation, fin movement, jet propulsion
What are the two types of thrust generation
Drag based (paddling ducks)
Lift based (sharks)
What is anguilliform swimming
Whole body undulation used by long bodied fish like eels and sea snakes
What’s carangiform swimming
Partial body undulation, with movement mainly in the rear half of the body (eg cod trout)
What’s thunniform swimming
Swimming primarily using the tail, common in fast swimmers like tuna
What changes as fish switch from anguilliform to thunniform swimming styles
Reduced body movement
Increased tail-fin emphasis
Streamlined shapes for speed
What type of fin motion allows a seahorse to stay stable and move slowly
Undulations of its paired fins while keeping the body stable
How does a pufferfish maintain its position against a current
By using undulating paired fins for fine motor control with minimal body movements
Describe the fin movement in a manta ray
Large, slow undulations of the wings spread out from the body
What’s a pro and con of undulating fin locomotion
Pro: reduced drag from moving smaller areas
Con: limited thrust power due to reliance on smaller fin muscles
What’s a hydrofoil in the context of aquatic locomotion
A lifting surface in water that generates lift forces
How does a hydrofoil based fin differ in thrust direction from anguilliform swimmers
Hydrofoils generate lift-based transverse thrusts
Anguilliform swimming generates drag-based thrust
What’s the difference between homocercal and heterocercal tails
Homocercal: have symmetrical lobes
Heterocercal: have elongated upper lobe and reduced lower lobe
How do flippers function as hydrofoils
They generate lift through flapping or angled positioning
