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Phylum Chordata
What Is A Chordate?
4 characteristics present at some stage of life
1. A dorsal, hollow nerve cord (called spinal
cord in vertebrates)
2. Notochord – a supporting rod (develops
into a backbone in vertebrates)
3. Pharyngeal pouches
4. Tail that extends beyond the anus
General Chordate Structure
Notochord
Muscle Segments
Tail
Anus
Hollow Nerve
Cord
Mouth
Pharyngeal
Pouches
Nonvertebrate Chordates
• Tunicates - look nothing like
other chordates
– The larval form has all the
chordate characteristics
– The adult tunicates have
neither a notochord nor a
tail
• Lancelets are more fishlike
and have a definite head
containing a mouth
Fish
Classes:
Agnatha – jawless fish
Chondrichthyes – cartilaginous fish
Osteichthyes – bony fish
Groups of fish
Fish are the first vertebrates to evolve
• Jawless Fish – have not true teeth or jaws; ex:
lampreys & hagfish, parasitic
• Cartilage Fish – skeleton made of cartilage; ex:
sharks, rays, skates
• Bony Fish – skeleton made of hard, calcified
tissue  bone; ex: perch, goldfish
Characteristics
• Integumentary
– Scales & paired fins
• Skeletal/ Muscular
– Endoskeleton - made of cartilage or
bone
• Circulation
– 2-chambered heart; closed-single loop
circulation
Characteristics
• Reproductive
– Internal or external;
– Oviparous, Ovoviviparous, Viviparous
• Eggs house outside the mothers body
• Born alive after developing eggs inside of mother’s
body
• Bear live young that are nourished by mother
• Nervous
– Brain, lateral lines
• Respiratory
– Gills
Characteristics
• Digestive
– Variety in types of feeding; complete
digestive system
• Excretory
– Remove ammonia from gills & kidneys
Characteristics
• Body Temperature
– Ectothermic
• Habitat
– Marine & Fresh Water
Bony Fish Structures
Dorsal Fins
Eye
Lateral line
Mouth
Caudal
fin
Operculum
Pectoral
fin
Anal fin
Pelvic fin
Swim Bladder
Spinal Cord
Reproductive
organ
Brain
Gills
Heart
Liver
Gallbladder
Intestine
Stomach
Anus
Amphibians
Class Amphibia
• Amphibians are tetrapod vertebrates
(four footed)
• Include all tetrapod vertebrates that
are not amniotes (lay eggs on land)
• Frogs, toads, salamanders, and newts
Characteristics
• Integumentary
– Moist skin with mucus glands
– Found near moist habitats to keep skin
damp
• Skeletal/Muscular
– Endoskeleton
– Adult: legs for walking or jumping; no
legs
– Larva: swim
Characteristics
• Circulatory
– Adult: 3 chambered heart, closeddouble loop
– Larva: 2 chambered heart
• Reproductive
– External fertilization; eggs must stay
moist (no shell)
Characteristics
• Nervous
– Brain; eyes w/ nictitating membrane;
tympanic membrane (like a drum) for
hearing; lateral lines
• Respiratory
– Adult: through lungs, skin, & lining of
the mouth
– Larva: through skin and gills
Characteristics
• Digestive
– Complete digestive system (mouth -->
anus)
– Adult: carnivore
– Larva: herbivore or filter feeder
• Excretory
– Kidneys filter wastes from blood, urine
travels through ureters to urinary
bladder and out through cloaca
Characteristics
• Body Temperature
– Ectothermic (cold blooded, find heat
from an outside source like the sun)
• Habitat
– Adult: live on land near water
– Larva: live in water
Lifecycle of a Frog
Adult
Frog
Young Frog
Adults are typically ready to
breed in about one to two years.
Frog eggs are laid in water and
undergo external fertilization.
Fertilized Eggs
Tadpoles
Tadpoles gradually grow limbs, lose their tails and gills, and
become meat-eaters as they develop into terrestrial adults.
The eggs hatch into
tadpoles a few days
to several weeks
later.
Evolution
• The first amphibians looked similar
to lobe-finned fish
Groups of Amphibians
•
Salamanders – have long bodies & tails,
most have 4 legs, usually live in moist
woods
Groups of Amphibians
• Frogs & toads – both jump & lack
tails; frogs more closely tied to
water
Groups of Amphibians
• Caecilians – legless animals; live in
water or burrow in moist soil; many
have fishlike scales,resemble
earthworms or snakes