unit 2 Flashcards
Living in water poses some challenges
- Obtaining oxygen
- Adjusting buoyancy
- Maintain body temperature
- Maintenance of a stable internal environment (due to movement of water & ions)
Most aquatic vertebrates exchange1 _______ and 2 ________ from the body via 3____
- O2
- CO2
- gills
how do amphibians exchange gasses
through their skin
Gills of teleosts are
-found in opercular cavity
-covered by operculum to prevent backflow
-unidirectional waterflow
gills project off of
gill arch
Gas exchange occurs on the ____ ____
secondary lamellae
Two ways fish are able to ventilate
- Buccal pumping: mouth & opercular
cavities pump water across the gills due to positive pressure produced (gulp water, close mouth, pump water over gills) - Ram ventilation: fish swims with their
mouth open to pass water across the gills
• Many pelagic & filter feeding fish do this
• Others may switch when actively swimming
Ram ventiliation
Passage of water _____ movement of
blood: ______ ______
opposes
counter current excahange
Most fishes use ____ to extract O2 from water
Gills
what is a labyrinth
-vascularized chamber at the rear of the head
-used to exchange oxygen and CO2 after gulping air
Bony fish - buoancy
neutrally buoyant due to well developed swim bladers
what is a physostomous fish
-have a gas bladder and pneumatic duct
-gulp air to push it to gas bladder to float more
-release air to sink more
what is a physoclistous fish
-fish with vascularized gas bladder
-have a rete mirabile (wonderful net)
-gas can diffuse across the membrane
counter current exchange
-literally means “bellows closed”
Cartilaginous fish - buoyancy
High oil content in liver
– do not have swim bladders
Deep-sea fishes- buoyancy
use lipids in a gas
bladder or through the body
refractive index of water is _____ than air
greater
lens in fishes
-refract more than terrestrial eyes
-make it possible to see in water
sound travels ______ in water than air
faster
(wavelength of given frequency is 4x longer in water)
Chemosensation
used to detect food, migration, etc
mechanorecptors detect ______ through water displacment
sense touch, pressure,
sound & motion
example of mechanoreceptors
lateral line to detect movement or vibration
Found in fish, larval amphibians & adult aquatic salamanders
electricity in water
water conducts elec –> orgs produce ele discharge –> used to detect preds, courtship or territory defence
Other organisms have
electroreception
Sharks respond to small changes of the electric field via ampullae of Lorenzini
shark food detection experiment
sharks prefer electical over chemical (smell) signal to find food
Class Chondrichthyes two groups
Elasmobranchii: elasma = plate & branchia = gills
– Between 5 and 7 gill openings on each side of the head
• Includes extant sharks, skates & rays
• Hyostylic upper jaw suspension- upper jaw not fused to the chondrocranium, permits it to be projected and retracted (SUUUUCK)
- Holocephali holo = whole; cephalo = head
– Includes ratfishes/chimaerans
– Single gill opening
– Holostylic upper jaw suspension- upper jaw fused to the chondrocranium
Class Chondrichthyes: common Charecterisitcs
- Placoid scales
– Composed of dentine and enamel with a pulp cavity
-tooth like structure
-also called denticle
-reduce friction as they move through the water
-rough and tough
-grow more scales as they grow in size (the scales do not get larger) - Cartilaginous skeleton
* Ancestral condition of vertebrates
* Mineralized with hydroxyapatite. Bone from
osteichthyans are also mineralized with
hydroxyapatite but deposited differently.
* Not necessarily weaker than bone
* More buoyant than bone
-more flexible - Teeth whorls of sharks
* dentine, enameloid & traces of bone
* Not embedded in the jaw (sit on jaw bone)
* Constantly being shed and replaced - Internal fertilization
* Males have pelvic claspers for
internal fertilization
-associated with pelvic fins - Lipid-filled liver
* Less dense than other body tissues and may be large to Facilitate buoyancy
* Skates & bottom dwelling species have smaller livers so they Sink to sea floor
Elasmobranchii- The Sharks
http://ipfactly.com/hammerhead-sharks/
Clade Selachii
• Highly diverse group
• Marine apex predators
• Many derived locomotor, sensory and behavioral adaptations
Elasmobranchii- The Sharks– Vision
Well developed vision permits vision at low
light
* Rod rich retina with platelike crystals of guanine : tapetum lucidum
-eye shine
-acts like mirror and reflects light
-adaptation that concentrates even low light