Phylum Chordata
Taxonomy
•
Phylum Chordata
– Subphylum Cephalochordata- amphioxus or lancelet
– Subphylum Urochordata- tunicates or sea squirts
– Subphylum Vertebrata
• Class Agnatha- jawless and cartilaginous, hagfish and lamprey
• Class Chondrichthyes- cartilaginous, sharks and rays
Fish
• Class Osteichthyes- bony fish
Cold
• Class Amphibia- cecilians, salamanders, frogs, toads
Blooded
(Ectotherm) • Class Reptilia- snakes, lizards, turtles, tortoises, alligators,
crocodiles, tuataras
• Class Aves- birds
Warm
Blooded
• Class Mammalia- dogs, cats, lions, horses, cows, bears,
(Endotherm)
giraffes, elephants, monkeys, kangaroos, humans, platypus,
mice, beavers, seals, sea lions, walruses, whales, dolphins,
porpoises, manatees, dugongs, anteaters, armadillos, sloths,
bats, shrews, moles, hedgehogs…
18 ft. Oarfish
Characteristics of Chordates

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•
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Dorsal notochord ~ rod of tough, flexible tissue
running the length of the animal’s body and
serving as its primary support.
*In most chordates, notochord is replaced by
vertebrae before birth or hatching.
Vertebrae ~ composed of either a tough flexible
material (cartilage) or bone
Vertebral column ~ all the vertebrae together.
Characteristics of Chordates

•
Dorsal tubular nerve cord ~ located dorsal to the
notochord or vert. column. The nerve cord and
brain, which is attached to the anterior end of the
cord, compose the main part of the nervous
system.
*the vertebrae may encase the nerve cord to
protect it.
Characteristics of Chordates

Pharyngeal pouches ~ are present during embryonic
development. Are folds of skin along the neck.
–
–
In aquatic organisms openings develop at the pouches. Allow
water flow over gills.
Non aquatic organisms ~ pouches develop into structures
located in the lower face, neck and upper chest region.
Subphylums
 Cephalochordata ~ Aquatic, have notochords
entire lives.
Amphioxus or lancelet, typical cephalochordate,
eel-like creature, about 2 inches long.
Subphylums
 Urochordata ~ have notochords in larval
stage.
Tunicates or sea squirts ~ typical urochordate,
pump water through small pores on their
bodies. Tadpoles of these animals have all
three of the characteristics of chordates, but
lose all but pharyngeal slits as adults.
Subphylums
Vertebrata ~ contains animals with backbones.
Vertebrates live in virtually every habitat from the
ocean floor to the upper fringes of the atmosphere.
95% of Chordates are Vertebrates. Great variety
within subphylum.
Vertebrata Classes
Seven classes of Subphylum Vertebrata:
First five are Ectothermic ~ cold-blooded, does not have the ability
to generate its own body heat or maintain a constant body
temp. above its surroundings. Depends on heat from other
sources to stay alive:
1. Agnatha ~ jawless fish, lack bone or paired fins. Examples are
lamprey and hagfish
2. Chondrichthyes ~ cartilaginous skeleton, paired fins. Examples
are sharks, skates and rays.
3. Osteichthyes ~ fish with bony skeleton. Examples are bass,
perch, trout.
4. Amphibia ~ lay eggs in water, have aquatic larval stage.
Examples are frogs, toads and salamanders.
5. Reptilia ~ dry scaly skin, amniotic egg, internal fertilization.
Examples are turtles, snakes and alligators.
Vertebrate Classes
Endothermic ~ warm-blooded, generate their own body hear to
maintain body temp. within a narrow range. May burn 30
times as much energy as an ectothermic animal of the same
weight.
6. Aves ~ hollow bones, flying feathers. Examples are any bird,
flamingo, penguin, robin, etc.
7. Mammalia ~ hair, nurse young with milk. Examples are dogs
lions and humans.
Support and Movement
Endoskeleton ~ internal skeleton that vertebrates have.
Functions/Characteristics:

surround, protect and support delicate organs

Movement occurs due to muscles that cover
bones.

Permits greater freedom of movement than an
exoskeleton

Much lighter than an exoskeleton
Two divisions of skeleton

Axial ~ consists of vertebral column, skull, and
ribs

Appendicular ~ composed of girdles and limb
bones
Two girdles
A. Pectoral ~ the anterior region
B. Pelvic ~ posterior
Circulation and Excretion
Vertebrates have a closed circulatory system, which means
the blood stays within the blood vessels during its
journey through the body.
Contains :
1.
Heart, which can have 2-4 chambers
2.
Blood vessels
Three types:
A. Arteries ~ carry blood away from the heart to body
tissues. Highly oxygenated.
B. Capillaries - terminal branches of the arteries. Thinwalled vessels that pass through body tissues, that
supply tissues with nutrients and oxygen and remove
wastes and carbon dioxide from tissues.
C. Veins ~ begin in capillaries and carry blood from
body tissues back to the heart. Very low in oxygen,
high in wastes.
Hemoglobin ~ red, iron containing, oxygen-carrying pigment
present in red blood cells.
Kidneys ~ filter out wastes carried by the blood stream.
Nutrition
Feeding methods of vertebrates:
1.
Carnivorous ~ animals feed upon
other animals. Have sharp teeth,
claws or other specialized structures
to help with process.
2.
Herbivorous ~ animals eat plants.
Have grinding teeth to breakdown
cellulose of plants, and often bacteria
in digestive tract to aid process.
3.
Omnivorous ~ eat both plants and
animals. Have a variety of teeth to
aid in eating both.
Alimentary canal ~ composed of an
esophagus, stomach and intestines.
With the liver, gallbladder and
pancreas as accessory organs.
Composes the digestive system of
vertebrates.
Reproduction
In most vertebrates, the sexes are separate.
Males ~ have paired testes that produce sperm
Females ~ have paired ovaries that produce eggs.
Methods of fertilization
1.
External ~ male fertilizes the eggs by releasing sperm onto them after the female
lays them. Takes place in water, and eggs have no shell.
2.
Internal ~ male places the sperm inside the female’s body where the eggs are
fertilized.
Three basic methods of embryo development:
1.
Oviparous ~ produce offspring from eggs that hatch outside the body.
2.
Viviparous ~ produce live offspring that have been nurtured to birth inside the
uterus or similar structure in the mother.
3.
Ovoviviparous ~ organisms produce live offspring that were not nurtured through a
direct connection to the mother. The fertilized egg often with a shell, remain in the
mother’s body and hatch there. Benefit for egg because of the more constant
body temperature of the mom.
Nervous system contains:
1.
Brain
2.
Spinal cord
3.
Cranial nerves (branch from the
brain)
4.
Spinal nerves (branch from the
spinal cord)
5.
Sensory organs( eyes, ears, taste
buds)
Divisions of the Five major lobes of the
brain, from anterior to posterior:
1.
Olfactory lobes ~ receive impulses
from the smell receptors of the
nostrils
2.
Cerebrum ~ controls voluntary
muscle activity
3.
Optic lobes ~ Receives impulses
from the eyes
4.
Cerebellum ~ coordinates muscle
activity and some involuntary
activities
5.
Medulla oblongata ~ transports
impulses to and from the spinal
cord, including some reflexes.
Nervous
System
Vertebrate Behavior
Behavior ~ the way an animal responds to its environment.
Three types of vertebrate behavior:
1.
Inborn behavior (innate behavior) ~ behavior that the organism has from birth and
does not need to develop.
A.
B.
Reflex behavior ~ automatic, involuntary response to a stimulus.
Examples: blinking and recoiling from pain
Instinct behavior ~ elaborate behaviors, apparently the result of a stimulus or series of stimuli.
Examples: salmon returning to birthplace, mating rituals, self-preservation
2.
Conditioned behavior (learned behavior) ~ response learned by experience.
Examples: spraying by skunk, eating something bitter or toxic, training.
Modeling ~ learning important behaviors by watching others of their species.
3. Intelligent behavior ~ the ability to use knowledge to manipulate the environment or
the ability to communicate, which can be instinctive or learned.
Examples: chimps using stones to crack open nuts, twigs to fish out termite
mounds, woodpecker finch using cactus spine to dig out grubs.