Sharks Exam 2 Flashcards
What are types of predatory behavior?
chasing, hunting by speculation, ambushing, stalking, luring, scavenging
What type of body makes sharks ideal hunters?
Fusiform
What kind of feeders are sharks?
Opportunistic feeders
What is speculative hunting?
They hunt in area that they assume will have fish or
follow another animal that may lead it to food. This is a learned or innate/genetically programmed behavior.
Example of speculative feeding?
Rays position themselves at high tide water movement areas and wait to be flushed out.
Tiger sharks aggregate during june/july during fledging periods of birds, eating the them as they land on the water.
What is ambushing?
Hidden, waits for prey to come to it, then launches at prey as it comes by.
What is stalking?
Uses stealth and approaches prey.
What is the difference between stalking and ambushing?
Ambushing prey comes to it, where stalking predator goes to prey
What kind of hunting do white sharks do?
stalking and speculation
What is luring and example?
Lure prey to eat. Cookiecutter sharks glow or flash and fish are attracted to it. Parasitic shark.
Kite fin and Greenland do similar
White tip shark is believed to attract prey with tips of fins. Hunt in groups one lures fish in until it is surrounded.
WHat does a tiger shark do?
scavenge but not exclusively. dead whales and fish
Do sharks do cooperative or group foraging?
possibly, not known if its cooperative or aggregations. Aggregations of shark work together to feed.
Sevengill sharks encircle a seal slowly tightening the circle until one strikes.
Thresher sharks herd fish with tail.
Black tip drive bait on to the beach
Generally eat one at a time.
How do sharks avoid predation?
disruptive coloring, false eye spot, cyrpsis, spines, large body size, electric discharge, crypsis and immobility
What is disruptive coloring?
morphology-has patterns, bar up/down or stripes head to tail
ex. rays blend in with surrounding to avoid hammerhead
What is false eye spot, how does it work?
Large round spots generally in a location that is affordable to lose. Other thought is that it startles the fish enough to get away.
Eye is big, makes fish look bigger.
What is crypsis?
has appendages that look like seaweed or coral. Acts like camo, allow them to hide to catch prey and be hidden.
Can have both crypsis and disruptive coloring
How do spines help?
Most are poisonous spines. ie Horned shark
Example of avoiding predation with large body?
Whale shark
What is capable of electric discharge?
California electric ray and common electric
How do crypsis & immobility work?
Ray buries itself in the sand and remains still until prey comes by or it detects the electrical signal
How do sharks behaviorly avoid predation?
refuging, display, schooling
What are two types of refuging?
biotic refuging-gather in a group, hide in numbers, not necessarily school
abiotic refuging-move to shallow water
What is the apparent looming threshold?
the point at which the distance and the size of the object makes one flee.
An advantage to having a long beak, fish focus on the body size and don’t see the beak until it is too late
How do behavioral displays work?
drops pectoral fin, then moves up and down in the water column. Confused, attacking and withdrawing, attacks out of fear
Are these proven predation behaviors?
No, none of these have ever been proven
How does schooling avoid predation?
Reduced predation due to the confusion affect. Predators cant fixate on one fish when there are many moving.
Also diluted affect-the predator cant eat all of the fish.
Fish are considered schooling when?
they are polarized and synchronized. increased vigilance.
What are types of prey capture?
suction feeding, bite feeding, ram feeding
What is pure suction feeding?
predator is stationary and prey is moving or being sucted out
ex.bamboo and nurse, spotted eagle ray
What is pure ram feeding?
prey is not moving only predator
predator moving at high rate, prey is stationary
ex. white shark-very little suction
What is bite feeding?
prey is not moving
predator moving at medium rate, prey is stationary
ex.hammerhead shark uses cephalofoil to stun ray then bites
What type of mouth do suction feeders have?
round small mouth, laterally occluded by labial cartilage (swings forward making opening), rapid jaw opening ( 35ms to open), enlarged hypertrophied jaw abductor muscle, small teeth, little cranial elevation
What type of mouth do ram and biting feeders have?
larger mouth with lateral gape, slower mouth opening, powerful jaw adductor muscles, large cutting teeth, cranial elevation during capture
What is the ancestral feeding method?
Suction feeding
what is the suction feeding range?
3-5 cm
What sharks are generalist feeders?
Dogfish and leopard, suction and ram
What are types of filter feeding?
intermittent suction filter feeding - open and clothes mouth
ex.megamouth and whale shark
continuous ram filter feeding-mouth always open
ex.manta ray, basking shark
What type of feeding does a megamouth do?
engulfment feeding
What type of jaw do sharks, skates and rays have?
Sharks have hyostyly - jaws connected to cranium by hyoid and anterior ligament
Skates and rays have euhyostyly-jaws connected to cranium by hyoid only
What are the functions of protrusion?
1-shark or ray can pick things off the bottom
2-gouges pieces of prey
3-decreases the time to close the mouth
4-may align the mouth with the prey better
5-allows to reposition the prey or bite
What is monognathic heterodonty?
each jaw has one type of teeth
What is dignathic heterodonty?
different teeth on one jaw
What type of teeth do rays have?
Mouth plates
What kind of teeth do indeterminant growth animals have?
polydont teeth, teeth get bigger as animal grows bigger
Do biologists use pressure or force for biting?
bite force
to penetrate it takes 10-20N
Leaning is pressure not force
How is bite force related to shark size?
The larger the shark the higher the bite force.
ex. Bull shark, TL285 cm, 478lb on front, 1330lb on back
Bonnet head, TL 96 on front, 35.4lb on back
Where is bite force greatest?
Closest to the hinge
How do sharks remove on wanted objects from their stomachs?
They invert it
ex. Mako. Dogfish cannot invert stomach
Are intestines the same?
No, four different kinds of folds. Carnivores have short intestines. Herbivores have long
Does diet vary among sharks?
yes, Large sharks eat marine mammals
small sharks eat fish
What is Ontogenetic dietary switch?
A sharks diet changes as it grows. teeth change as well.
How do we analyze stomach contents?
gastric evulsion-types include: stable isotope analyzes (isotopes change with type of food), PVC pipe/hand, flush out stomach
however diet is biast to hard stuff, versus soft tissue
What is total gastric evacuation time?
varies considerably but longer than bony fish. greater than 50-100 hours
Preferred diet of sharks?
S. tiburo - blue crab
P. glauca(blue shark)-squid
H. francisci(CA horned shark)-urchins
White sharks - switch bony to marine with growth
How long do sharks feed?
intermittent feeders-not eating machines-opportunistic
whale sharks feed 7-8hrs
some eat once may not eat again for several days
eat 1-3% of body weight per day
What time of day do sharks prefer?
Little evidence of increased feeding at dusk or dawn
velocity goes up at night many nocturnal
ex bonnethead, horned shark and nurse
What is the difference between red muscle and white muscle?
Red muscle is for continuous swimming
white muscle is for burst speeds
What kind of fish maintain warm muscles?
tuna and lamnid sharks
Where is lamnid sharks RM?
It is in the center of the shark, right and left of the vertebrae column.
How did the twitch time vary?
RM had 3s long twitch duration - Q10 of 3.7
WM had 51-143 ms,Q10of 2.
What are the stable temp of each muscle?
RM - 26C or higher, low temp long twitch duration slow muscle movement, high temp faster twitch
WM - 10-26C, muscle twitch remained constant over change
WHat happens if RM cools?
It will cease to contract, fish will sink and die
What else does RM warm?
White muscle
Endothermy vs ectothermy
internally regulated via red (s) muscle vs environment regulates heat
What is rete mirable?
it is a network of countercurrent blood vessels.
-the heat is transferred to the blood going the opposite way. the heat is internalized and does not dissipate to the outside
muscle contractions generate heat
What shark family is endothermic?
lamnidae-mako, salmon, white and parbeagle
WHat special features do lamnideas have?
lateral cutaneous rete
sometimes an orbital rete-eye
suprahepatic rete - anterior to the liner
higher metabolic rate
What is the temp of Mako, white and salmon?
Mako - 8C
White - 14C
Salmon - 18C
What are the common factors between endothermic tunas and sharks?
- RM is typically medial towards the red line and anterior
- elevated body temperatures; rete
- myotomes-most elongated
- thunniform and homocircal tail
- red muscle is separated from the white muscle by loose connective tissue (red contraction is out of phase with the white contraction)
Where do tendions run down?
core of myoseptum to tail.
WHat do tendions do?
transfer force down to tail
WHat order to the RM and WM fire in?
White first, red second = eventually i sequence
What is tendions in phase with?
white muscle
Why are muscle separate?
so they can fire separately
Why do sharks warm their bodies?
move better, swim faster
stay warm as they dive- maintain speed and power
What do endothermic sharks have?
large gills, relatively large hearts, greater hemoglobin levels, higher enzyme activity
WHat is Q10?
the rate of change for every 10 degrees
What muscle has a higher twitch time?
RM overall was greater
Who is an obligate endotherm?
lamna ditropis-salmon shark
- has to keep swimming to maintain body temperature
- if it loses heat to RM it will never regain
What is the difference between isometric and isotonic?
Isometric is where the muscle TRIES to contract
Isotonic is where the muscle DOES contract
