Animals Behaviour & Anatomy Flashcards
What are primary swimmers?
Invertebrates and fish
What are secondary swimmers?
Marine reptiles and birds
What are the 3 main issues for both, primary and secondary swimmers?
- Buoyancy
- Drag reductions
- Maintenance of orientation and direction
Marine organisms are denser than water, how do they cope with the problem of buoyancy?
- through reduction of their density
- continuous movement
1. when negative buoyant –> propulsion (some fish and cephalopods) - static or dynamic buouyancy
What examples are there for static buoyancy control?
- Reduction of heavy tissue
- Inclusion of low specific gravity substances: lipid, oil
What examples are there for dynamic buoyancy control?
- Swim bladder (functions as a hydrostatic organ: also plays a role in respiration, sound production and sound reception)
- In Nautilus through differential chamber filling
- In surfing snails the secretion of a mucous bubbles to “surf” at the water surface
What do we know about the swim bladder?
- in all Teleost
- gas-filled sac (CO2, O2, nitrogen)
- functions as hydrostatic organ
- involved in gas release and gas addition
- in some Actinoperygii they are filled with oil
How much more denser and more viscous is water than air?
Water is about 800 times denser and 50 times more viscous than air. Locomotion through this dense, viscous medium is energetically expensive.
The most energetic costly factor in locomotion is drag. What two different types of drag are there?
- viscous or frictional drag: it involves friction between the fish’s body and the surrounding water; as a consequence, this drag depends on the surface: total area and smoothness;
- inertial or pressure drag caused by pressure differences that result from displacement of water as the fish moves through it; it depends on the body shape and increases with the speed.
What is a convergent evolution of teleost and elasmobranchs?
Streamlined body shape
What is a tradeoff between hydrodynamic shape and?
e.g. reproductive success
Hydrodynamic shape
- width/length=0.25
- max width at 2/5 of the body
- fins folded in grooves or depressions –> maintain the streamline
- reduce the surface
- smooth surface: mucous secretion, compact fur
What reduces drag?
(3 things, one goes hand in hand with other)
- hydrodynamic shape
- smooth surfaces(mucous , compact fur)
- types of scales (reduction of vortices formation)
Jet propulsion
- method of aquatic locomotion
- animals fill a muscular cavity and squirt out water to propel them in the opposite direction of the squirting water
- the force of water expulsion determines speed
- usually used together with other locomotion modes, by species like cephalopods (squids, cuttlefish, octopus), jellyfish.
What are the two swimming types (lots of intermediates)?
UNDULATION
OSCILLATION
What is the Lateral force and thrust in swimming behaviour of fish?
- lateral push excepted on water during movement
- reactive force can be divided into the two components
1. lateral force
2. thrust - adaptation for effective swimming:maximization of thrust respect to lateral component.
–> there is an optimal angle: ca 18°
What do good swimmers present ?
- hydrodynamic shape
- stiff vertebral column
- tips of caudal fin pointed
- caudal peduncle flattend
- keels (reducing drag or adding propulsion force)
Formula Aspect ratio
Aspect ratio = height2/surface area
- good swimmers = high aspect ratio: large caudal fin height and small surface
- from <1 up to 10
What are adaptations for a rapid acceleration from a standing start?
- posterior propulsive elements
- large dorsal and anal fins
- placed far to the posterior
- caudal peduncle is deep
- tail has a relatively high aspect ratio (but lower than that fast swimmers like tunas)
- maximum thrust in the tail region
What are finlets?
- adaptation for swimming
- prevent vortices from developing in water moving from the median fins and body surfaces towards the tail
- allows the tail to push against less turbulence
With what habitat are keels associated in sharks?
Pelagic habitats
Different tail shapes of sharks
What is an adaptation in terms of temperature regulation to maintain high swimming capabilities?
Maintaining high (body) temperatures, higher then environmental temperatures –> e.g.Tuna
How can thermoregulation be accomplished?
- Behavioural : moving to warmer areas
- Physiological: red muscles (Tunids & Lamnid sharks) –> counterurrent system: cooler blood encounters warmer blood before reaching the bulk of red muscles in the middle of the body, so higher body temperature can be maintained
What convergences present Tunis and Lamnid sharks?
- streamlined body shape
- lunate shape of caudal fin
- ram ventilation (saves energy)
- negative bouyant
- high aspect ratio
- bulk of red muscle in the middle of the body (teardrop body shape & stiff-bodied swimming)
Adaptations of good swimmers to reduce energetic costs
- ram ventilation instead of buccal pump
- high gill surface
- high concentration of haemoglobin
Why do some fish swim in schools?
- Antipredatory
- Feeding
- Swimming (minimizes vortices formation)
What are adaptations of fish that live in complex environments such as coral reefs?
- shape typically laterally compressed
- tall body to ensure high maneuverability
- oscillation or undulation of dorsal, anal or pectoral fins
- 65% uses labriform swimming mode
- speed depends on shape of pectoral fins
- pectoral fin aspect ratio correlates with water velocity
- speed is correlated positively with the aspect ratio in species belonging to different families
speed, cruising efficiency, rapid acceleration, maneuverability are things that shape the body, caudal fin etc. and reflect performances of the fish
Swimming modification examples of fish
- walking on pectoral fins
- boxfish can only use pectorals
- electric field
Modification of pectoral fins that allow movement on land
- Pectoral fins have a robust proximal
part, while distal part allowing the
support. - Pectoral girdle is robust.
What can we say about secondary swimmers?
- use mainly flippers and are good in maneuverability but only a few are fast swimmers
- forelimbs are deeply modified to function as oars. They are used to maintain the balance.
- Joints are lost, stylopodium and zeugopodium are reduced and autopodium is stretched.
Pitch, yaw and roll need to be limited in order to maintain swimming performances (orientation and direction). How is this achieved?
Pair and unpair fins help in balancing the animal.
Roll is hindered through pectoral and unpair fins
Yaw is hindered by a rigid head and body shape and rigidity.
What are the three main feeding types in the marine environment?
- Suspension feeding
- Deposit feeding
- Active or passive feeding
trophic web
Why is a first spiny ray a defence mechanism ?
Because prey has to be ingested head first
List prey defences
- first spiny ray
- inflating body
- toxic substances (Cuvierian organ)
- camouflage
- aposematic colorations (alert toxicity)
- schooling (Dilution & confusion effect)
List mechanisms for prey capture
- toxic substances to stun prey
- Electric shock
- Head adaptations (e.g. hammerhead)
- Teeth / gill rakers to grab prey
Where is the mouth of fish positioned in relation to what they feed on ?
- Superior if fish feed on preys above them
- Terminal if preys on fish in front of them
- Inferior if feed on fish below them
What is the development of sensory organs dependant on ?
habitat, the type of preys, the life style
–> species preying in the water column usually rely more on vision, species preying on benthic species hidden in the bottom rely more on chemosenses
Sensory system parts in the brain
Differences in sensory systems concerning habitat
Reef associated bentho-pelagic fishes have more developed telencephalon
–> Right or wrong?
Right
Cerebellum foliation index tends to be higher in pelagic and oceanic species
–> Right or wrong?
Right
Olfactory bulbs (OB) large in bathyal species (this is common also in teleosts).
–> Right or wrong?
Right
OB small in species associated with coral reefs (vision is more important)
–> Right or wrong?
Right