Zoology Test 3d Flashcards
Subphyla of Chordates
- Urochordates
- Cephalochordates
- Vertebrata
types of Urochordates
- tunicates or sea squirts
types of Cephalochordates
- lancelets or amphioxus
super classes of Vertebrata
- Agnatha
- Gnathostomata
Agnatha
- hagfish
- lamprey
- jawless vertebrates (primitive characteristic: came from jawless ancestors)
classes of Gnathostomata
- Chondrichthyes
- Actinopterygii
- Sarcopterygii
jawed vertebrates
types of Chondrichthyes
- sharks
- skates
- rays
- chimeras
types of Actinopterygii
ray-finned bony fish
types of Sarcopterygii
lobe-fined bony fish
five features of chordates
- notochord
- dorsal nerve cord
- pharyngeal gill slits
- postanal tail
- endostyle or thyroid gland
characteristics of notochord
- supporting structure of chordate body
- present in all life stages of primitive chordates
- present only in early stages of advanced chordates
- replaced by vertebral column during development of advanced vertebrates
characteristics of dorsal nerve cord
- dorsal, hollow nerve cors
- clusters of ganglia at anterior end of nerve cord (brain or CNS)
characteristics of pharyngeal gill slits
- outer ectoderm comes into contact with endoderm of pharynx and openings are formed
- original use was pharyngeal filter feeding, later, gills were added to arches between slits
- been retained and put to other uses
- forms jaws and inner ear; forms tonsils, parathyroid, thymus and eustachian tube
what are the arches?
supportive structure that lies between each gill opening
characteristics of endostyle/thyroid gland
- secretes mucus that traps small food particles brought into pharyngeal cavity
- secretes iodine-contianing porteins
- homologous to thyroid gland in vertebrates
characteristics of postanal tail
- tail extends beyond anus
- used in propulsion through water
- retains this function in many chordates, but is present in embryo of all chordates
characteristics of Urochordates
- “tunicata” because a covering (“tunic”) containing cellulose surrounds body
- some species forcefully discharge a jet of water from excurrent siphons when irritated
- about 2000 species
- marine
- mostly sessile
- solitary, colonial and compound forms all occur, compound forms share single tunic
- closed circulatory system
why do tunicates have excurrent siphon?
they are pharyngeal filter feeders that pull water into basket-like pharynx via action of cilia
- water exits via the excurrent siphon
postanal tail in tunicates?
- free swimming larva posses all five chordate characteristics
- undergoes metamorphosis and loses tail and notochord, dorsal nerve cord reduced
- becomes sessile adult
characteristics of cephalochordates
- 2-3 inches long
- inhabits sandy bottoms of marine coastal areas around world
- anchors itself into bottom via tail
- filter feeds
- only 25 species
- have all five characteristics
- closed circulatory system
- sexes separate
- simple nervous system
- simple sense organs
feeding in cephalochordates
- water in mouth, then through pharyngeal slits
- endostyle produces mucus to capture particles
- water exits pharynx then leaves body thru atriopore
- food in mucus cord enters digestive tract
chordate evolution
- all current evidence points to fee-swimming creature as ancestral chordate, with sessile tunicates representing secondary condition
characteristics of vertebrata
- cranium (braincase)
- 3 part brain
- head with paired sense organs
- 2+ chambered heart
- other physiological changes to support high metabolism
characteristics of lampreys
- smooth, scaleless skin
- paired pectoral and pelvic fins are absent
- only have single dorsal fin
- notochord persists throughout development and present as main supporting structure in adult
- ventrally located circulatory system with two chambered heart
what is unique about lampreys?
- undergo metamorphosis from ammocoete larva to adult
- ammocoete larvae probably resembles ancient ancestor
feeding in lampreys
- some use their sucker-like moth to parasitize fish; can kill host because they don’t stay long
- others eat vegetation
What is a fish?
- aquatic vertebrate with gills
- appendages in form of fins
- skin with scales of dermal origin
- gnathostomes
jaw evolution in Gnathostomes
- jaws formed from the gill supports (gill arches)
- considerable anatomical evidence supports idea-relics of this transformation are seen during development of modern sharks
characteristics of appendages in Chondrichthyes
paired pectoral and pelvic appendages
Chondrichthyes skeleton
- a living endoskeleton, no need to molt
- is totally cartilaginous
- cartilaginous skeleton is secondarily derived, since ancestors of sharks had true bone
- skeleton can grow with the organism
characteristics of sharks
- whale shark (39 feet long, 47000 lbs)
- eats plankton collected on a sieve mesh over its gills, thus filter feeder
- basking shark and megamouth sharks are filter feeders
most sharks are what kind of feeders?
- most are predators
- replaceable teeth
- sensitive palette
sensory adaptations in sharks
- large olfactory organs can detect prey from kilometer or more away
- can detect chemicals in water as low as 1 part per billion
- extreme separation of nostrils in hammerhead sharks, which may enhance stereo-olfaction
- follow chemical gradient
- lateral line system
- composed of special neuromast cells in pores that extend length of body
- lamprey and bony fish have lateral line system too
- acute sense of hearing
- excellent vision, even in dim water
- ampullae of Lorenzini sense of bioelectric fields that surround animals
other adaptations in sharks
- shape and skin allow bursts of speed up to 18 mph
- skin allows them to be hydrodynamically quiet
- large liver filled with squalene that helps to maintain buoyancy despite large body
- neterocercal tail that allows them to stay afloat
squalene
oil with density only 86% that of water
osmoregulation in sharks
- retain nitrogenous compounds in blood to raise blood solute concentration above that of seawater
- rectal gland secretes fluid containing high concentration of NaCl
what are sharks vulnerable to overfishing?
- slow rates of maturation and reproductive turn-over
- give birth to relatively minuscule numbers of young when compared to other fish
- many species breed only every other year and have 13 month gestation period
shark finning
- cut off fins which kills them
- don’t kill sharks before finning
- makes shark fin soup
- shark cartilage helps cure cancer
circulatory system in Chondricthyes
- two chambered heart
- closed circulatory system
reproduction in Chondricthyes
- dioecious
- internal fertilization
shark reproduction
- oviparous
- ovoviviparous
- viviparous
oviparous
some lay eggs
ovoviviparous
many have eggs that hatch inside the body
viviparous
some sharks have primitive placenta and give birth to fully-formed young
How do skates and rays differ from sharks?
- most are specialized for bottom dwelling
- dorsoventrally flattened body with greatly enlarged pectoral fins that are fused to head and used like wings in swimming
- water enters gill chambers via dorsally-located spiracles behind eyes, to prevent clogging of gills with sand
reproduction in rays
viviparous
reproduction in skates
oviparous
feeding in rays and skates
- most have crushing teeth to feed on molluscs, crustaceans and fish
- some (electric rays) can produce strong electric discharge to stun prey of for protection
- some (manta ray) are plankton filter feeders, like whale, megamouth and basking shark
characteristics of electric ray
- produce 8 to 220 volts
characteristics of manta rays
- have remoras as passengers (cleaner fish)
