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

1. Scales

2. Fins

3. Throats with gill slits

We are water-dwelling vertebrates that usually have 3

characteristics.

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• 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• Fish scales overlap like shingles on a roof.• 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.

Amphibians

• 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.

&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• 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

Aves

• 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.

The Science of Bird Flight

Aves• 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 owls.

• Hunting birds, waterfowl, & songbirds = 3 major bird groups

Birds• 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.