Lecture Exam 2 Flashcards
List the Features of Superclass Gnathosomata
-Jaws (derived)
-Fins (dorsal, pelvic, anal, and pectoral; all derived)
-Heterocercal Tail (primitive)
-Paired External Nares (primitive)
-Indicates that Gnathostomes came from Pteraspid ostracoderms
List the Features of Class Chondrichthyes
-No bony elements (derived feature that is unique to them)
-Skin with bony plates-replaced by small denticles of dentine in later Chonrichthyes-derived feature, unique to Chondrichthyes
-Jaws with teeth of dentine (dervied from scales-shared with all gnathosomes except placoderms)
-Paired fins with girdle elements (derived)
-Jaws suspended by hyoid arch (derived)
-Jaw muscles lateral to jaws (derived)
-Predaceous
-Paired fins, heterocercal tail, paired external nares
-Paired lateral keels at base of caudal fin-like extant pelagic sharks
List the Features of Class Oseichthyes
-Operculum-shared with Acanthodii
-Gas filled swim bladder (or lung) present-this is an outpocket of the esophagous used for buoyancy in water (or respiration)
-Paired nares
-Tail variable
-Paired fins
-Jaw suspended by hyoid
-Bony scales
-Jaws with teeth
-Jaw muscles lateral to jaws
-21,000 species
-biggest group of modern vertebrates
Describe the Scale Types Found Among Fishes
-Cosmoid Scales:
-in primitive sarcopterygians
-on a double layer of bone:vascular and lamellar
-outer surface is a thick layer of dentin
-superficially on the dentin is a thin layer of enamel
-Ganoid Scales:
-found in gar
-thick surface coat of enamel
-no underlying layer of dentin
–dermal bone forms the foundation either double layered: vascular and lamellar or a single layer of lamellar bone
-scales shiny, overlapping, and interlocking
-Teleost Scales:
-lack enamel, dentin, and vascular bone
-only lamellar bone-acellular and mostly noncalcified
-cycloid-composed of concentric rings
-ctenoid: a fringe of projections along its posterior margin
-fish can be aged by counting ciculi
Compare the fins of Subclass Actinopterygii with those of Subclass Sarcopterygii
-Fins of Subclass Actinpterygii
-Ray Finned Fishes
-No muscle in fins for support in body wall (retained from Acanthodii)
-Multiple elements support fin
-Dorsal esophageal outpocket forms swim bladder
-Evolution with radiation based on modified swim bladder and locomotion; modified scales
-Fins of Subclass Sarcoperygii
-Lobe-Finned Fishes
-Single basal element to pelvic and pectoral fins (homologous to limbs and girdles of tetrapods-land vertebrates)
-Muscle enters base of fin
What are labyrinthodont teeth?
-specialized grooved teeth
-cone shaped, grooves that run from the tip of tooth to base
List and describe the unicellular glands found in fishes.
-Club Cell: elongate, sometimes binucleate, unicellular
-produces chemicals that cause alarm or fear
-may warn others of danger
-contributes to the mucous cuticle
-Granular Cell: found in skin of lampreys and other fish
-contributes to the mucous cuticle
-Goblet Cell: not in lampreys but in other bony or car fishes
-contributes to the mucous cuticle
-Sacciform Cell: produces a chemical that acts as a repellent or toxin against enemies
Describe the three skull regions of fishes.
-Chondrocranium: surrounds brain and special sense organs
-Splachnocranium: develops into the branchial arches; supports the gills and makes up jaws and gills
-Dermatocranium: develops in the dermis; formed of dermal bone that overlays chondrocranium and splanchnocranium
Describe jaw suspension among fishes
-Amphistylic: some sharks; jaws and hyoid arch are braced directly against the braincase
-Autostylic: lungfish, chimaeras, and tetrapods; hyomandibular cartilage not involved; “self bracing”
-Hyostylic: most chondricthyes, some bony fishes; hyomandibular cartilage braced against the chondrocranium; jaws braced against the hyomandibular cartilage
Describe the types of caudal fins found among fishes
-Diphycercal: lungfishes and bichirs; unlobed
-Homocercal: lobes about the same size; vertebral column doesn’t extend into either lobe
-Heterocercal: sharks; one lobe larger than the other
-Epicercal: vertebral column extends into dorsal lobe
-Hypocercal: vertebral column extends into ventral lobe
Describe the forces acting upon swimmers.
-Gravity pulls down; sinking in the water column
-Buoyancy pulls up; rises in the water column
-Propulsion pushes forwards
-Drag pushes backwards
Describe how fishes are efficient swimmers.
-To reduce pressure drag in water they are long and thin like an eel
-this displaces the least amount of water
-To reduce frictional drag be stout and round to reduce surface area or be smooth and slimy
-mucous reacts with water to reduce viscosity
Compare Primitive and Derived fish body shapes with respect to swimming
-Primative:
-Head tends to pitch down
-Heterocercal tail has propulsive force pushing tail down and therefore head up
-Tail controls pitch (up and down motion of head)
-Roll controlled by pelvic and pectoral fins
-Derived:
-Center of gravity above center of buoyancy
-Heavy roll potential
-Circle swimming pattern if there is a homocercal tail
-Swimbladder: out pocket of gut, lung-like
-big gas bag that alters buoyancy
-Why fish float belly up when they die
Describe gill respiration among fishes
-Buccal cavity controlled by hyomandibular muscles
-increases surface area
-Water flows in the opposite direction of blood
-counter current flow: allows for efficient transfer of oxygen from water to gill lamellae capillaries
-Mechanisim:
1) operculum closed; mouth is open; hyomandibularis relaxes; water enters buccal cavity
2) hyoid muscles relax; draws water across gills, down as far as it can go
3) mouth closes; hyomandibularis contracts forces water across gills
4) hyoid muscle contracts; hyomandibularis contracts, greatest pressure in buccal cavity, forces water across gills
5) operculum opens – water flows out of the opercular chamber; hyomandibularis continues to force water across gills, Insures one way flow forward – counter current is continually in action
Describe the various ways fishes procure prey
-Vertebrates feed on huge variety of prey items (plankton to whales)
-Eating Plankton
Need Water pump and Strainer
Cant sit and wait
Not a primitive condition for vertebrates
Ammocoetes larvae of lamprey retain primitive condition
Pump water through gills (pharyngeal muscles)
Plankton trapped on mucus on gills
All other vertebrate strainers represent convergent evolution
Need some thin mesh and then method to transport to gut
Eating Vegetation
Need clippers to sever vegetation
Need grinders to break down cellulose and get organic chemicals
Who eats it?
Fish; algae eating species
Stoneroller: blade like lower jaw to scrape algae off rocks; beak like jaws move stones as they feed
Pharyngeal arches of some suckers form crushing teeth for grinding up algae; but if you grow these on snails they develop other teeth
Eating Fruit
Note that fruit is designed to be eaten to disperse seeds
Is high value and easy to digest
No consistent set of adaptations
Who eats fruit?
Fish
Fruit falls in river which the motion of is picked up by fish
Consumed while swimming which deposits seeds in feces
Important force in determining tree distribution
Eating Large, Active Prey
Now dealing with animals that are trying not to get caught
Two Strategies:
Wide-Foraging: seek and destroy; actively search out
Sit and Wait: ambush; cryptic coloration for specific objects; generalized crypsis, counter shading
luring ; cephlic; angler fish
Pedal; ceratophrys frog; wave hand
Caudal; copperhead; gold tail
