Biology Chapter 30
What is a Fish?
1. Classified in the phylum “chordata”
2. Includes 3 “subphyla”
a. Urochordata – sea squirts
b. Cephalochordate – lancelets
c. Vertebrata – the vertebrates
3. In addition to fish the subphylum vertebrata include:
a. Amphibians
b. Reptiles
c. Birds
d. Mammals
4. Remember – all chordates have 3 traits in common
a. Notochord
b. Sill slits
c. Dorsal nerve cord
5. Invertebrates of the embryo the notochord is replaced by a backbone
6. All vertebrates are:
a. Bilaterally symmetrical
b. Coelomates
c. Have an endoskeleton
d. Closed circulatory system
e. Nervous system with complex brains and sense organs
f. Efficient respiratory systems
Three Classes of Fish
1. Agnatha – lampreys and hagfish
2. Chondrichthyes – sharks and rays
3. Osteichthyes – bony fish
Agnathans are Japanese Fish
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Hagfish have slit like toothed, mouths
Feed on dead or dying fish
They drill a hole and suck the blood and insides out
Lamphreys attack themselves by their sucker-like mouth’s and suck insides out
Both skeleton (like sharks) are made of cartilage
Agnathans have gills made up of feathery gill filaments that contain tiny blood vessels
Agnathans reproduce sexually
a. Have separate sexes
b. External fertilization
c. Most produce a large number of eggs
d. Hagfish produce a small number of large eggs
8. 2 chambered heart
a. One chamber receives oxygenated blood from the body
b. The second chamber pumps blood to the gills where oxygen is picked up and carbon
dioxide is released
Carbon + Rays
1. Posses skeleton composed entirely of cartilage
2. Have paired fins
3. Fins are fan shaped membranes supported my stiff spines called rays
a. Used for balance, swimming, and steering
b. Fins foreshadow the dev. Of limbs used on land and wings for flying
Jaws evolved in fish
1. Advantage of a jaw is it enables an animal to grasp and crush its prey with great force
2. Can consume large chunks of food – can grow larger
3. Are predators
Sharks + Rays
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2.
3.
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Extremely sensitive sense of smell
Can detect small amounts of chemicals in the water
Sharks can follow a trail of blood for miles
“Lateral Line System” is a line of fluid filled canals running along the sides of a fish that
detect movement and vibrations in the water
5. Rays have sharp spines with poison glands
6. Some can separate electricity
Cartilaginous Fish have Scales
1. Most fish have skin covered by overlapping rows of scales
2. Scales are made from bone formed by skin
Sharks + Rays have Internal Fertilization
1. Sharks and Rays may produce as few as 20 eggs and keep them inside their bodies until they
have hatched and developed to about 40 cm in length
Bony Fish
1. The majority of the worlds fish belong to the class “Osteichthyes”
2. All bony fish have bony skeleton, gills, paired fins, and a highly developed, dense organs
3. Have skeletons made of bone
4. Bone is hard, mineralized, living tissue that makes up the endoskeleton of moist vertebrates
Vertebrates Provide Flexibility
1. The evolution of a backbone composed of separate, hard segments called vertebrae was
important
The Development of the Swim Bladder
1. Another key to the success of body fish was the evolution of the “swim bladder”
2. A “swim bladder” is a thin-walled internal sac just below the backbone
a. Can be filled with gas that diffuse out of the blood
b. Fish control their depth regulations the amount of gas in the bladder
i. It works like gas in a blimp
Reproduction in Bony Fish
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Sexes are separate
Fertilization is external
Breeding in fish and some other animals is called spawning
Some (cod) produce as many as 9 million eggs
Some fish are live – bearers – supplies + mollies internal fertilization young develop inside
Three Subclasses of Bony Fish
1. Lungfish – have both lungs + gills
2. Lobe – finned fish – one living species
3. Ray – finned fish – fins are supports by rays – catfish, perch, salmon, cod
Amphibians – the move to land – had challenge
1. Life on land hold many advantages for amphibians
a. A large supply of food
b. Shelter
c. No predators
d. Much more oxygen in the air
e. Life on land also held many dangers
i. Temperatures change
ii. Without water the body was heavy and clumsy
Adaptation Improved Success
1. Support + efficient locomotion
2. Protection for membranes involved in respiration and circulation
What is an Amphibian?
1. Completely aquatic to air breathers
2. Amphibian means “double life”
3. Class amohibian has 3 orders
a. Urodela – salamanders + newts
b. Auura – Frog + toads
c. Apoda – legless caeciluim
4. All rely on water for breeding
5. Eggs must be laid in water to keep them moist
6. Fertilization external – water needed to transport sperm
Amphibians undergo metamorphosis
1. Fertilized eggs hatch into tadpoles
a. Have fins
b. Gills
c. 2 chambered heart
2. Tadpoles grow into adult frogs + toads
a. They develop legs
b. Lungs
c. 3 chambered
Amphibians are ectotherms
1. Ectotherms is an animal in which the body temp changes with the temp of its surroundings
2. Amphibians become dormant in regions that are two hot or too cold – hibernation –
estivation
Walking requires more energy
1. More energy from food + large amounts of oxygen for aerobic respiration
2. 3 chambered heart ensures cells receive proper amounts of oxygen
3. In the 3 chambered heart, one chamber receives rich oxygen rich blood from the lungs and
skin another receives oxygen poor blood from the body tissues. Blood from both chambers
then move to the 3rd which pumps oxygen rich to body tissues and oxygen poor to lungs and
skin
4. In amphibians the skin is much more important than the lung as an organ of gas exchange
5. Skin must stay moist to exchange gases
Diversity of Amphibians
1. The move from water to life on land is not complete
2. Part of their life cycle needs water (reproduction)
Frogs + Toads belong to the order “Huura”
1. Vocal cords are sound productive bands of tissue in the throat
Slalmanders – order Urodela
1. Have a neck and tail
2. Have smooth moist skin
3. Lack claws
Origins of Amphibians
1. Ist appeared 350 million years ago
2. Evolved from lobe – found fish
3. Climate changed to warm and wet
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What is a Reptile?
Snakes, turtles, alligators, and lizards- all share certain traits that place them in the class
reptilian
Reptiles have scaly skin- have a dry thick skin covered with scales
Scaly skin prevents the loss of body moisture and provide additional protection from
predators
Reptiles are entirely dependent on lungs as their organs of gas exchange their skin is too
thick
Some reptiles have 4 chambered hearts
Most have a 3
Crocodilians have a 4 chambered heart
a. Completely separates the supply of blood with O2 from that without CO2
Skeletal changes in reptiles
1. Have legs placed more under the body rather than out to the side
a. Makes walking and running on land easier
b. Better chance of catching prey and avoiding predators
c. Also have claws that facilitate food getting and protection
3. Other changes in the structure of the jaw and teeth allows them to exploit other resources
and niches on land
Reptiles Reproduce on Land
1. They reproduce by laying eggs on land
2. The “amniotic egg” was the adaptation that liberated reptiles from dependence on water for
reproduction
3. The amniotic egg provides nourishment to the embryo and contains membranes that protect it
while it develops in a land environment
A. The egg functions as the embryos total life support system
4. All reptiles have internal fertilization
5. Eggs are laid after fertilization
6. Embryos develop after the eggs are laid
7. They lay their eggs under rock, bark, grasses—a few dig holes and build nests
8. Most provide no care for their hatchlings
9. Female crocodiles guard their nests
Retiles are ectothermal
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Both amphibians and reptiles are ectotherms
Their body temperature depends on the temp of their environment
They do no inhibit extremely cold regions
Are very numerous in the temperate and tropical
Many reptiles become dermal in moderately cold environment—US
Reptile adaptations—how they obtain food
1. Turtles and tortoises- are too slow to be predators- most are herbivores or prey on worms and
mollusks
2. Snapping turtles are aggressive- will attack fish, amphibians, pull ducklings under water
3. Lizards eat insects
4. Snakes are effective predators
A. Poison
B. Constrictors
How Reptiles use their sense organs
1. Snakes have heat-sensitive organs that can detect variation in air temperatures brought
about by warm blooded animals
2. Keen sense of smell – snakes and lizards
3. Jacobson’s organs – tongue picks up chemicals in the air and inserts tongue in the jacobson’s
organ
Diversity of Reptiles
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Snakes and lizards belong to the order squamta
Turtles belong to the order chelonian
Crocodiles and alligators belong to the order crocodilian
Turtles have shells
a. Turtles that live on land are tortoises
5. Crocodiles include the largest living reptiles
6. Snakes and lizards are found in many environments
7. Snakes usually kill their prey in one of 3 ways:
a. Constrict
b. Venoumous
c. Most snakes are neither constrictors no poisonous they get their food by grabbing it
with their mouth and swallowing it whole
Birds- what is a bird
1. After conquering the sea and land vertebrates took to the air where there was a huge source of
insect food and refuge
2. There are 9000 species of modern birds classified in the class aves
3. Reptile features of birds
a. Clawed toes
b. Scales on their feet
c. Internal fertilization
d. Shelled amniotic egg
Birds have feathers
1. Birds can be defined simply as the only organisms with feathers
2. A feather is a lightweight modified scale that provides insulation and enables flight
3. Preening- hooking feathers
4. Molting- shedding of old feathers
Bird Bodies are adapted to flight
1. Front limbs are wings
2. Sternum- where powerful muscles are attached
3. Flight requires high levels of energy
a. 4 chambered heart
4. Are endotherms warm blooded- constant body temp
5. Bones are thin and hollow
6. Can live in all environments
7. Beaks are reflection of the food they eat
Other bird adaptations
1. In spite of basic uniformity of birds, they do exhibit specific adaptations depending on the
environment in which they live and the food they eat
A. feathered legs- snow birds
B. Penguins are flightless
C. Large eyes
D. Acuter sense of hearing
E. Sharp claws
F. Bird beaks are a reflection of the food they eat
Mammal characteristics- what is a mammal?
1. Are endotherms- warm blooded- constant body temp
2. Can live in every possible environment on earth
Mammals have hair
1. Only mammals have hair
2. Hair thought to have evolved from scales
3. Provides insulation water proofing conserves body heat
How mammals cool off
a. Adaptations for cooling off the body
b. Panting- dogs
c. Sweat glands
3. A gland is a cell or group of cells that secrete fluid
4. Mammals have several kinds of glands
a. Saliva
b. Milk
c. Digestive
d. Enzymes- 30
e. Hormones- 70
f. Sweat
Mammals have a diaphragm
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It enables large amounts of oxygen to enter the body and reach all the cells- trillions
The diaphragm helps expand and contracted the chest cavity
A diaphragm is a sheet of muscle located beneath the lungs
The diaphragm separates the chest cavity from the abdominal cavity
a. Contractor enlarges this chest cavity
b. Relax- the cavity becomes smaller
Adaptations for obtaining and consuming food
1. Mammal limbs are adapted for a variety of methods of food getting
Adaptation for consuming food
1. Teeth are a distinguishing feature for most mammals
2. The type of teeth determine what kind of food is eaten
a. Incisors- cut
b. Canines- tear
c. Premolars- grind
d. Molars- grind
3. Cud chewing- the hoofed mammals- cows- they have 3 stomachs
Mammals nurse their young
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Mammals guard their young fiercely and teach them survival skills
Mammals feed their young from mammary glands
Female mammary glands secrete milk
It enables mothers to nourish their young until they are mature enough to find food and protect
themselves
Mammals are intelligent
1. Mammals can accomplish complex behaviors, such as, learning and remembering what they
have learned
2. Primates including, humans are perhaps the most intelligent animals
a. Chimpanzees can use tools, work machines, etc
b. Intelligence is a result of complex nervous systems and highly devoted brain
How Mammals are classified
1. Scientist place mammals into one of 3 subclasses based on their method of reproduction
a. The first is the placental mammals – their young develop within the uterus of their
mother
b. The uterus is a hollow, muscular organ in which the development of the offspring takes
place
c. Nourishment of the young inside the uterus occurs through an organ called the
placental which develops during a pregnancy
d. The time during which young placental mammal developed inside the uterus “gestation”
e. 95% of all mammals are placental
2. Marsupials – make up the second subclasses of mammals
a. A marsupial is a mammal in which the young have short period of development within
the mother’s body, followed by a second period of development inside the pouch
3. Egg – laying mammal
a. A monotrem is a mammal that reproduces by laying eggs
b. The duck-billed platypus has hair and mammary glands
Orders of Mammals
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Insectovorea – shrew
Chiroptera – bat
Primate – marmosets
Edentate – anteater
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Lagomorpha – pikas
Rodentia – mice
Cetacea – whale
Carnivora – dogs – cats
Pinnepedia – walruses
Proboscidea – elephant
Perissodactyla – horse
Artiodactyla – hippo
Siremia - monatees