Exam 1: ppt 5-9 Flashcards
buoyancy system
liver, gas bladder
alimentary canal
the passage along which food passes through the body from mouth to anus
anterior region of alimentary cnal
buccal cavity (mouth), pharynx (gills)
posterior alimentary canal
foregut (esophagus & stomach), midgut (intestine), hindgut (rectum)
digestive system is usually longer in…
herbivores
stomach functions
storage of food
initiation of digestion
inactivation of pathogens
jawless fish lack…
stomachs
pyloric caeca
fingerlike pouches at beginning of intestine
known to secrete enzymes that aid in digestion
intestine function
primary site of nutrient absorption
spiral valve
spiraling fold of tissue in elasmobranchs and primitive bony fishes
increases surface area
because fish have no salivary glands…
the mouth, buccal cavity and pharynx specialize in seizure and control of food
fishes of the families Tetraodontidae & Diodontidae can
expand their stomachs with air or water when threatened
buoyancy
ability to regulate vertical position within the water column
why don’t fish sink?
hydrodynamic force from swimming counteracts gravity
gas bladders
low weight cartilaginous skeletons and low specific gravity
lungs and gas bladders are…
homologous
there are no animals with both…
lungs and swim bladder
first lungs were simple sacs that…
connected to the gut and allowed organisms to gulp air in low O2 environments
gas bladders evolved from…
lungs
physostomous gas bladders
more ancestral and less prevalent
air flow is controlled by the pneumatic sphincter
physoclistous gas bladders
more derived; most bony fish
no physical attachment to gut
air moves from blood to fill gas bladder at the gas gland
tunica externa
layer of guanine crystals that covers the the bladder’s outside and is impermeable to gas
gas gland
vascularized portion of gas bladder, extracts gas from blood into the bladder
rete mirable
net of blood vessels, uses countercurrent exchange to help the gas gland efficiently extract O2 from the blood
oval window
gas permeable, allows gas to leave the bladder, controlled by constrictor muscles
movement of gas happens by diffusion so…
a concentration gradient with high O2 in the blood is created
lactic acid is produced by the gas gland which…
disassociates to lactate and hydrogen ions
the increase in hydrogen ions leads to…
an increase in pH of the blood
under conditions of high pH hemoglobin unloads its O2 thus…
increasing the concentration of O2 in the blood and allows for diffusion
fish regulate the loss of gas in the bladder by
1) controlling the flow of blood to the oval window
2) and by using muscles to regulate the amount of gas entering the oval window
specific gravity
ratio of the density of a substance in reference to fresh water
seawater has an SG of…
1.06-1.09
Bernoulli’s Principle
points of higher fluid speed will have less pressure
circulation system
single loop with 4 chambers/sacs
four chambered fish heart
blood enters from the body:
through the Ducts of Cuvier > sinus venosus > atrium > ventricle > bulbus arteriosus > leaves the heart to the gills
gills
main site of gas exchange
stiffened pairs of bony or cartilaginous gill arches anchor…
gill filaments
____ pairs of gill arches each with ____ rows of filaments on each arch
4; 2
lamellae
highly vascularized; facilitates uptake of oxygen from water
gills must have…
high surface area and moisture for extracting O2 from water
gill filaments are arranged so that…
the flow of water is counter to the flow of blood in the vessels
ventilation
respiration is most efficient when water is continuously flowing over gills
ram ventilation
forward swimming motion carries water into mouth
ex. some predatory pelagic fishes
2-phase (buccal-opercular) respiratory pump
phase 1: buccal and opercular cavities expand while the opercular valve is closed = negative pressure
phase 2: mouth closes, buccal chamber contracts, opercular valve opens forcing water across the gills
buccal pump
expand buccal activity; water rushes into buccal cavity via mouth; contraction of buccal cavity forces water over gills
buccal pumping can be used
to breathe when not swimming
lamprey ventilation
external gill openings for moving water in and out of gill pouches when feeding
hagfish ventilation
velum moves water through the nostril and over the gills
skin breathing
O2 diffuses directly into epidermal capillaries
air gulping
surface air is swallowed, and O2 diffuses through vascularized internal tissues
facilitative air breathing
air breathing supplements gill respiration
obligate air breathing
air breathing required for survival
most air-breathing fishes live in…
tropical habitats
“true lungs” only found in…
lungfishes
walking catfish use…
arborescent organs
tarpon primarily use gills to breathe but…
can acquire O2 from their gas bladder
mudskippers rely on…
cutaneous respiration when on land
mechanorecption
detection of the movement of water
chemoreception
detection of chemicals in water
electrorecption
detection of electricity
magnetic reception
sensing magnetic fields
lateral line allows for
touch/feel, detecting prey, avoiding predators, schooling
inner ear allows for
hearing, balance, gravity detection
hair cells
bundled into the neuromasts
mechanoreceptors
neuromast morphology
cupula, kinocilium, & stereocilia
canal neuromasts
sit at the bottom of pits or canals
abundant in species living in moving, clear water
superficial neuromasts
sit on the surface of skin
abundant in species living in less turbulent water
neuromast function
help in the detection of disturbances in water
pars superior
three semicircular canals filled with endolymph
