Lec 8 Flashcards
Adaptations to increase Buoyancy
Some vertebrates carry large quantities of oil, fat, and other substance less dense than water
Adaptations to decrease buoyancy
some vertebrates have unusually thick and dense bones
Adaptations to flexible controls of buoyancy
Some fishes carry swim bladders with adjustable volume of gas
Wall of gas bladders contain guanine crystals, to prevent gas loss
Some derived fishes travel great vertical distances, loss their swim bladder
Two types of gas regulation
Physostomus
Physoclistous
Physostomus
Gas bladder is connected to the stomach via direct connection
Gulping air at surface to fill gas bladder
Burping air out via jawed mouth
Typically, gas bladder is filled at the surface before descend and released during ascend
Physoclistous
Gas bladder is connected to a network of vessels called rete mirabile
Gas gland excretes lactic acid and carbon dioxide to lower pH at contact between rete mirabile and gas bladder
Hemoglobin releases oxygen due to low affinity at low pH
Sphincter of ovale allow gases to enter ovale, and reabsorbed into the blood stream
Limitations of gas bladder
Contribute to barotrauma
Barotrauma
Drastic changes in pressure lead to expansion of gas bladder
Rule of thumb of Dr.Murray
Slow ascend at about 1 metre per hour, though some species can do up to 3 metres per hour
Locomotion: The Manus Invisibia
Main fluid dynamic forces in the environment
Weight
Lift (must balance weight)
Drag (forward resistance)
Thrust (must overcome drag)
From whence thou drag
The rate of removal of momentum from moving water by an immersed body
Drag is approximately proportional to
Density of fluid
Square of the velocity of the fluid
Cross section area of the immersed body
Challenges of vertebrates concerning thrust and drag
Thrust producing and drag inducing structures are inseperable
Undulation
Pushing backwards and sideways against the water with the tail, or with a travelling wave that moves along the body
Backwards pushing creates
Thrust
Sideways pushing is cancelled out by
The sweep of the tail or body in the opposite direction
Dynamic lift for buoyancy is possible with
Continuous movements, especially with a heterocercal tail
Curvature of body is represented as
Waves
Level of undulation is represented as
Number of wavelengths
Three types of controls
Roll
Yaw
Pitch
All but … can be the primary structure of locomotion
Pelvic fins
Respiration usually occurs through
Flow through respiration with gills
Water flow is generated by muscles of
Flow through respiration with gills
The pharynx in cyclostomes and muscles of the jaw in gnathostomes
Gills are
Flow through respiration with gills
Thin sheets of soft tissues supported by skeletal system
Gills are typically made of
Flow through respiration with gills
Primary and secondary lamellae which contact numerous blood vessels
Water flow through gills lamellae with
Flow through respiration with gills
Massive total surface area
At gill vessel interface
Flow through respiration with gills
Oxygen is extracted from external fluid and channeled to tissue cells
More rare respiration
Ram ventilation
Air breathing in fishes
Water flow is generated by
Ram ventilation
Swimming with mouth and operculum open
Operculum
Bony cover of the gill
Ram ventilation can
Save energy of using muscles of the jaw
Oxygen is supplied from
Air breathing in fishes
Air through lung or accessory air breathing organs (ABO)
Air breathing in fishes evolved in response to
Low level of oxygen in aquatic environments
Osmoregulation
The process of maintaining both water and salt balance to prevent body fluids from becoming too concentrated or too diluted
Key principle of osmosis
Equalization of concentrations
(moving from high to low concentration)
Isosmolal
Being at equilibrium (Hagfish)
Hyperosmolal
Body has higher concentration (freshwater fishes)
Hyposmolal
Body fluid has lower concentration (sharks)
Stenohaline
Narrow environmental tolerance
Fishes that live in marine or freshwater
Euryhaline
Wider environmental tolerance
Fishes that migrate for breeding
Adaptations to see better
Round lens with high reflective index
Lens is moved in and out to adjust visual focus
Supply oxygen to the retina to form sharp images
Adaptations to lose the eye
Degenerate the eye tissue
Absence of the lens is crucial
Typical ways to sniff under water
Blind nasohypophyseal pouch
Nasopharyngeal duct connected to pharynx
Enclosed nasal sac with incurrent and excurrent nostrils
Lateral line anatomy
Neuromast organs with hair cells
Distributed on head, trunks and tail
Embryologically originated from ectodermal placodes
Electroreception
Ability to detect external electric fields generated typically by muscle activities to other vertebrates
Types of electroreception
Passive
Active
Ampullary organs made of
Passive
Highly conductive gel surrounded by non-conductive wall
Sensory cells extend into
Passive
The conductive gel to receive electric signals
Typically concentrated on the
Passive
Head and mouth, but can be found on pectoral fins and rays
Likely derived from
Passive
Lateral line placode
Function for
Passive
Orientation, prey detection, social recognition
Active organ
Electric discharge organ
Homologous with the
active
Neuromast organ, not the ampullae
Positive pole on the
active
Head
Negative pole on the
Tail, forms electromagnetic field around the body with the head
Function mostly to
Active
Locate prey
Electrogenesis
Somewhat unique use of the electric discharge organ
Induce voluntary muscle controls in prey
