EXAM 1 Flashcards
An era when the first shark-like fishes and ancestors of modern day species first appeared was __, which spanned from 450-245 million years ago
Paleozoic era
Most recent era when most modern day species of sharks and their relatives appeared was the __, which began about 65 million years ago
Cenozoic era
Symmoiiformes, Cladoselachiformes, and Eugeneodontiformes are examples of sharks that were common in the __ era
Paleozoic
Superorders of sharks
Squalomorphii and Galeomorphii
What is Taxonomy?
the science of classifying organisms
What is phylogeny?
classification system that takes into consideration the evolutionary history of species
Heliocoprion
this shark is known for its spiral tooth whorl
What are fossil records of elasmobranchs based almost entirely on?
teeth
The characteristics that are useful in shark classification as they vary among orders, families and sometimes species of sharks:
structure & number of vertebrae, design of eyelids, chondrocranium morphology
A source of information used in phylogenetics - used to group sharks and their relatives into orders, families and genera is:
a. morphological features
b. physioloy
c. dna
d. all of the above
ALL OF THE ABOVE
What structure found in sharks and their relatives are dervied from placoid scales?
teeth, fin spines, stinging spines, clasper spurs
Ways in which sharks and their relatives are distinct physiologically from most bony fishes?
Reproductive structures, giving live birth, lacking swim bladder, gill slits, cartilaginous skeleton
How do sharks reproduce?
Internal fertilization
What is spawning
male and female gametes released near each other in the water
Cladistics
a phylogenetic classification system that uses shared dervied characters and ancestry as the sole criterion for grouping taxa
Cladogram
Diagram that shows the evolutionary relationships among a group of organisms
What sources can potentially be used as a basis for determining phylogenetic relationships?
morphology, gene sequencing, specialized structures
What are the mechanisms for evolution other than natural selection?
mutations, gene flow, genetic drift
Give an example of an isolating mechanism that might result in speciation among Bonnethead sharks
sea level changing which created a geographical isolation between the sharks
How many orders of modern day sharks are there?
nine
What are the nine orders of modern day sharks?
Squatiniformes, Pristiophoriformes, Squaliformes, Hexanchiformes, Lamniformes, Orectolobiformes, Heterodontiformes, Carcharhiniformes, Echniorhinoformes
What is convergent evolution?
occurs when similar structures from different species appear as adaptations to the same environment
Example of convergent evolution in sharks
streamlined body style
What two dominant groups of modern day fishes arrived on earth a little more than 400 million years ago?
Osteichthyes, Chondrichthyes
What is the difference between Osteichthyes and Chondrichthyes
Osteichthyes are fish with skeletons of bone and, while chondrichthyes have a cartilaginous skeleton and include sharks and rays
What class are sharks in
Chondrichthyes
What subclass are sharks in
Elasmobranchii
How is the evolutionary history of elasmobranchs related to mass extinctions?
Mass extinctions in the past two eras have led to the rise of present day elasmobranchs due to lack of competition in other niches
What are the three eras in history of the Earth
Paleozoic, Mesozoic, Cenozoic
Because of inverse relationship between force produced and rate of shortening, muscles of large animals shorten ___ and generate ___ force per contraction
SLOWLY, MORE
An example of a tissue found in animals that is MORE dense than sea water
Skin
What is the advantage in using neutral buoyancy?
Energy saving
Which is NOT a species of shark included in the order Heterodontiformes?
Horn shark
Port Jackson shark
Japanese bullhead shark
Zebra shark
ZEBRA SHARK
Body shape that has lowest drag coefficient is:
Streamlined, teardrop shape
For most species of deep-sea sharks, their livers represent around __% of their body weight.
20%
Sharks in the order Heterodontiformes are commonly known as:
Bullhead sharks
The major buoyancy mechanism for deep-sea sharks is:
their liver
A low density (0.86) hydrocarbon found in large quantities in the liver oil of many deep-sea sharks is:
Squalene
The pectoral fins of sharks function to provide hydrodynamic lift in a similar manner as airplane wings provide aerodynamic lift. Both lifting surfaces generate lift due to ________ differences between the upper and lower fin/wing.
Pressure
How many species of elasmobranchs are there?
~1100
What is the common name of Heterodontid sharks
Bullhead shark
Characteristics of Heterodontid sharks?
Big prominent brow ridge, spines on dorsal fin, pig-like snout
How is the ability to move advantageous for animals such as elasmobranchs
Finding food, avoiding predators, finding a mate and producing young, remaining in a physiologically optimal environment.
Describe the relationship between force produced and rate of shortening of muscles.
The faster that muscles are shortened, the lower the overall force produced;
A slower rate of muscle contraction (shortening) yields greater overall force
Explain why large animals such as many species of elasmobranchs expend relatively less energy to move a certain mass a certain distance.
Energy consumption per unit mass per unit distance for large animals is much lower than for small animals
What factors influence the amount of drag experienced by an animal moving through water
Viscosity, body shape, surface area of body, speed of movement through water
Explain how dermal denticles of elasmobranchs reduce drag.
Water flows across the dermal denticles to reduce turbulence and drag, turbulence resists movement and drag limits the speed of movement
What structures on and around the tails of fast-moving fish reduce drag?
Finlets, scutes, keels and tubercles
What lifting surfaces are found in sharks, how does their shape create lift
Head and body, Pectoral fins, Tail
What is sustained swimming?
routine activity over long periods of time without muscular fatigue
What is prolonged swimming?
Over shorter periods of time, muscle fatigue, these swimmers do NOT rest
What is burst swimming?
VERY short periods of time, high velocity movement, usually used for prey capture or to escape from predators
How do skates and rays generate forward propulsion?
Using pectoral fins, will undulate [little waves] or oscillate [flap like wings]
What is anguilliform movement?
more head movement to propel forward, movement “like an eel”
What is caraganiform movement?
majority of movement is concentrated in rear of body and the tail
What is thunniform movement?
Head has the least rotation of all swimming forms, most movement coming from tail movement, very little overall body movement
How do shallow water sharks maintain their position in the water column
Generate hyrodynamic lift with fins and head, constantly moving
What major buoyancy mechanisms are common in deep water sharks?
Liver size, liver oil/lipids, muscle water
What low density lipids are common in liver oil of deep-sea sharks?
Squalene and DAGE
How does the density of Squalene and DAGE compare to that of triglycerides
Squalene and DAGE are significantly less dense than TG, especially squalene.
How large are the livers of deep water sharks?
20-30% of their bodyweight
What tissues and materials found in the bodies of elasmobranchs are more dense than surrounding seawater? less dense?
body tissues such as the skeleton, muscles, skin, and organs, are all more dense than seawater
Lipids are less dense than seawater, and make up a significant portion of the liver
