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Phylum Chordata
At some point during a chordates life,
all chordates will have a nerve cord, a
notochord, and a throat with gill slits.
Chordate Characteristics
• The nerve cord is a hollow tube near the
animal’s back that later develops into the brain
central nervous system.
• Beneath the nerve cord is the notochord. This is
a long, flexible supporting rod the runs through
the animal’s back. During development, the
notochord is replaced by the vertebral column in
most vertebrates.
• The 2 gill slits are located in the pharynx that
connects the throat with the air outside. Gills are
feathery structures which allow water-dwelling
animals to breathe, like fish.
Fishes
Fishes are water-dwelling vertebrates that
usually have:
1. Scales
2. Fins
3. Throats with gill slits
Fish Characteristics
-have a single-loop closed circulatory system (blood moves from the heart
to the gills to the body and back to the heart)
-have tubelike kidneys that filter wastes from the blood (excretory system)
-have a well-developed nervous system which include sense organs that
see color, smell, and taste
-have a swim bladder to regulate buoyancy
-In most fish species the reproductive system is found separately (male or
female) and they use external fertilization (eggs and sperm join outside
the body). A few species use internal fertilization (sperm joins an egg
inside the female’s body)
-include 3 classes of fishes: Jawless, Cartilaginous, & Bony
Jawless Fishes
• Are the most primitive of the
fishes
• Lack a jaw, scales, and paired
fins
• Made of cartilage instead of
bones, so they are really
flexible
• Have a notocord
• 2 examples are the eellike
lampreys and hagfish
• Both produce a mucus/slime
through its skin for protection
Cartilaginous Fishes
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Include the sharks, skates, rays,
sawfishes, & chimeras
Their skeleton is made of cartilage, the
same material that makes up your ear and
nose.
Most have toothlike scales so they feel like
sandpaper
Sharks can have up to 3000 teeth
arranged in rows
Skates and rays are flat as pancakes
Some rays have a poisonous spine used
for defense
Electric rays can stun & capture prey by
zapping them with 200 volts of electricity.
Our homes use 120 volts.
Bony Fishes
• Their skeleton is made of hard bones
• Have paired fins, but the shape will vary
• Have swim bladders to give them buoyancy, or
the ability to float at different levels in water
• Adaptations of fish include the ability to produce
650 volts of electricity, change its body color to
match the color of the ocean bottom, breathe air
through its skin, burrow into mud on land and
become inactive until the rains come, hitch rides
by suctioning on to a fish, secrete toxins through
its long spines, or have light-emitting organs to
attract prey.
Amphibians
• Thought to have evolved from the lobe-finned bony fishes with lungs
(coelacanths)
• Amphibian means double life (in water and on land)
• Breathe through gills when immature in water
• As adults, they breathe through lungs and moist, gland-filled skin on
land
• Lack scales and claws
• Their eggs lack hard outer shells so they must stay moist in water
• Adults with lungs have a double loop circulatory system/young with
gills have a single loop system
• Young undergo the process of metamorphosis (tadpole-->frog)
• Have 2 oval-shaped kidneys that filter wastes from the blood
• Have a well-developed nervous and sense organ system
• Many amphibians reproduce by external fertilization. Others use
internal fertilization.
Frogs AND Toads
• Both can hibernate underground during
the winter when temperatures drop
• Frogs have smooth, moist skin
• Toads have skin that is drier and usually
covered with bumps.
• Adults frogs & toads have powerful hind
legs used to escape from predators.
• Many toads can squirt poison from behind
their eyes for protection.
Salamanders &
ewts
• Both keep their tails throughout their lives, unlike
the frogs/toads.
• Are not able to jump due to underdeveloped hind
legs
• Need to live in moist areas
• Lay their eggs in water
• Mud puppies have both gills and lungs so are able
to live in water and land.
Reptiles
• Lay eggs that have a leathery, protective shell
• Have tough, dry relatively thick layer of scales that are waterproof to help
prevent excess water loss
• Cannot breathe through their skin (like amphibians), so lungs are
necessary
• Are cold-blooded; the air temperature determines their body temp
• Kidneys concentrate liquid waste to prevent water loss
• Have a double-loop circulatory system with a 3-chambered heart
• Have well-developed brain and nervous system
• Have internal fertilization in which the sperm cell joins the egg cell inside
the parent’s body. Egg cells are immense because they contain huge
amounts of stored food. Sperm cells are microscopic.
• Do not undergo metamorphosis like amphibians do
Lizards & Snakes
• Lizards have slender bodies, movable eyelids, long tails, 4 legs, &
clawed toes.
• Lizards are mostly insect eaters that lunge after their prey.
• Special lizard adaptations include using poison glands,
camouflaging, shedding their tail & regrowing it
• Snakes are lizards with no limbs, ears, and eyelids .
• Snakes move by wriggling its long, thin, muscular body.
• Have cool, dry, and smooth scaly skin
• Snakes eat small animals by either injecting poison through fangs or
strangling their prey through constricting air flow.
• Tongue-flicking helps snakes to analyze chemicals in the air to find
food.
• Special pits on the sides of their heads can detect heat from prey.
Turtles
• Are enclosed in a shell made
of bony plates covered by
shields made of the same
substance as scales
• Have no teeth, but beaks
• Some turtles eat plants,
others eat animals.
• Land-dwelling turtles with
domed shells are often called
tortoises.
• Sea turtles use navigation to
return to their birthplace.
lligators & Crocodiles
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Large, meat-eating lizardlike reptiles that spend much
of their time submerged in water
Have long snouts, powerful tails, & thick, armored skin
Alligators have broad, rounded snouts; crocodiles have
narrow, pointed snouts
Alligators have a few teeth showing when their mouth
is closed; crocodiles have many teeth visible,
Crocodiles are more aggressive than alligators
Most do their hunting at night, finding insects, fish,
amphibians, birds, and even large hoofed mammals
Build nests of mud or plant in which the females will
lay hard-shelled eggs. Some species take care of the
eggs.
Females can carry her babies in her jaws for safety.
Birds
• Not all species of birds fly (penguin, ostrich)
• Archaeopteryx (which means ancient wing) is the oldest known fossil
of a bird living 140 million years ago when the dinosaurs roamed
• Are warm-blooded, egg-laying vertebrates that have feathers
• Feathers are made of dead cells like what is found in your fingernails
• The large contour feathers are found on the body/wings. They give
birds their streamlined shape
• Down feathers are short and fluffy for insulation
• Birds eat a lot to get enough energy to fly and maintain their body
temperature because they’re warm-blooded
• Beaks are adapted for the type of food it eats
• Bird bones are hollow & therefore lightweight
Darwin’s Finches
Birds
• The respiratory system is more advanced in birds.
• Air sacs are attached to lungs which inflate and deflate to get a constant
supply of fresh air is moving in 1 direction through the lungs
• Birds have a double-loop circulatory system with 4 chambers. The 2 loops
are completely separated so oxygen provided by the lungs is delivered
effectively to the body cells.
• 2 oval kidneys filter nitrogen-containing wastes from the bloodstream
• The brain/nervous system is well developed. Eyesight & hearing can be
keener than humans in certain hunting birds like hawks.
• During breeding season the reproductive organs enlarge to a useable size
• Bird eggs will only develop if they are kept at the proper temperature by
the parent(s). Some young are born featherless & must be cared for.
• Nests can be just a shallow trench on the ground or quite elaborate.
• Many birds migrate to follow seasonal food supplies & warmer weather
• Waterfowl, songbirds, & hunting birds = 3 major bird groups