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Directional Terms You Must Know
Caudal towards the tail
Ventral towards the belly
Dorsal towards the back
Anterior towards the head
Posterior towards the rear Lateral to the sides
Medial towards the middle
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Distal farther from the core of thebody
Proximal closer to the core of thebody
Buccal mouth region
Pharyngeal muscular swallowingregion of throat
Integumentary the skin system
Respiratory dealing with gasexchange
Cardiovascular dealing with circulationof blood
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Chordate Evolution
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Four defining characteristics of
the phylum Chordata Notochord
Post-anal tail
Pharyngeal gill slitsor pouches
Dorsal hollow nerve
cord
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Advantages of Chordate
Characteristics Notochord provides stabilizing
structure and muscle attachment =
mobility in water Gill slits/pouches efficient oxygen
delivery system in large bodiedorganisms
Post-anal tail propulsion
DHNC No clear hypothesis why dorsalwould be any better than ventral
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Subphyla of the Chordates
Urochordata tunicates (sea squirts)
Cephalochordata Lancelets
(amphioxus)
Vertebrata more accurately called
Craniata, including anything with a
cranium
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Hypotheses on Vertebrate
Evolution Urochordate Ancestor: (1928) proposes larval
tunicates are ancestor; larval forms retained
form into adulthood and gained gonads toreproduce (paedomorphosis)
Cephalochordate Ancestor: (1991) proposes
a lancelet ancestor due to many fossil forms
that show notochord, myomeres, gillstructure, and caudal projections.
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Vertebrata Groups
Agnathans lampreys and hagfish
Gnathostomesjaw opening
cartilaginous fish, bony fish, amphibians,
reptiles, birds, & mammals
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Hagfish vs Lampreys No jaws
Cartilaginous
skeleton No paired or dorsal
fins
No eyes Many mucus glands
No jaws
Cartilaginous
skeleton No paired fins, but
dorsal fin present
Eyes well developed No mucus glands
AGNATHA
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Hagfish
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Lampreys
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GnathostomesAnimals with Jaws
Hinged jaws were the most importantevolutionary development
Jaw structure is thought to be derived fromthe first gill arch
Jaw was probably at first a hingedmechanism that prevented reflux of waterduring breathing
Jaws allowed new sources of food and newniches
MORE FOOD = BETTER SURVIVAL = MOREBABIES = MORE REPRESENTATIVES
WITH THOSE GENES FOR THE GOODTRAIT
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Jaw Development
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Development of Paired Fins
Paired fins include the pectoral and
pelvic fins.
Pectoral fins are used for balancing andturning
Pelvic fins are for stabilizing motion
Both kinds help control pitch, yaw, and
roll
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Pitch, Yaw, and Roll?!?
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Origin of Paired Fins
Paired fins might have evolved from the
most posterior gill arch, folds of the
body wall, or from spiny appendages
along the body.
The fossil record provides no clear
answer to which hypothesis is accurate
or if more than one may be accurate.
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Acanthoidians (spiny sharks)
that support the idea of fins from
spines
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Paired Finscontinued
Once paired fins arose, wide radiation
of fish groups occurred.
Many fish groups are now extinct, butfish are still the most abundant and
widespread vertebrate
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OsteichthyesChondrichthyes
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PlacodermsMean and Extinct
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Class Chondrichthyescartilaginous
fishSharks
Rays Skates
Chimaeras (Ratfish)
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Chondrichthyan characteristics
Cartilaginous skeleton
No bony structures except in the teeth
and scales
Placoid scales (hooked from the side
view)
Approximately 850 living species,
mostly marine
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Subclasses of the Chondrichthyes
Elasmobranchii sharks, skates, rays
Holocephali chimaeras (also called
ratfish)
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Skates vs Rays
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Skates vs Rays
Dorsoventrally
flattened
Hugely enlargedpectoral fins
More muscular tail
Usually 2 dorsal fins
Lay eggs in cases
Pelvic fin is one lobe
Dorsoventrallyflattened
Hugely enlargedpectoral fins
Whip-like tail
Sometimes
poisonous Dorsal fins usually
absent
Pelvic fin is 2 lobed
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Chimaera Facts Males have a single
clasper on the head
used for clenchingthe female during
mating.
The gills are
covered with afleshy flap.
They have grinding
plates rather thanseparate teeth.
Deep-sea dwellers
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Shark Facts Have 5 to 7 gill slits. Range in size from 7 inches long (dwarf
lanternshark) to 39 feet long (whale
shark)
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Birth Patterns
Oviparous laying eggs outside of the body,most often with external fertilization (salmon,
gray nurse shark)
Ovoviviparous eggs are retained in thefemale body but are not connected to her
during development, internal fertilization
(dogfish, hammerheads, coelacanths)
Viviparous egg is fertilized internally andretains a connection to the mother for
nutrients until birth (bull sharks, surf perch,
guppies, mollies)
S U i Fi h h
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Structures Unique to Fish that
Chondrichthyes and Osteichthyes
Share Lateral line system to detect pressure
waves.
Two chambered heart with single atriumand ventricle.
Have a range of birth patterns from
oviparous, ovoviviparous, to viviparousbirth.
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OsteichthyesThe Bony Fish
Bony Fish have skeletons made of
bone.
The two subclasses exist: the-ray finnedfish (Actinopterygii) and the lobe-finned
fish (Sarcopterygii)
The ray-finned fish comprise 97% of allliving species of fish.
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Sarcoptyergii Lobe-finned fish
have fleshy fins with
internal bones.
Lungfish and
coelacanths belong
to this group.
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Lungfish
Lung is a highlyvascularized swimbladder.
They do also have gills. Gulp air at surface
when oxygen levelsdrop.
Can survive droughtsby burying themselvesinto mucus-linedburrows.
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The Ray-Finned Fish
Ray finned means the fins are webs ofmembrane supported by internal bony
spines called fin rays. Have a bony plate covering the gills,
called the operculum.
Have a symmetrical homocercal tail.
Have a swim bladder used for buoyancyand gas exchange.