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Unit 13 - Vertebrates Student Guided Notes
Chordates
General Characteristics of Phylum Chordata
Although not the largest, Chordates are the most diverse phylum in the animal kingdom.
Chordates have _______________________________ at some stage of the life cycle
and have______________________made from an outgrowth of the digestive tube. All
chordates are deuterosomes and the blastopore during embryonic development forms
the anus. They show body segmentation and other characteristics present in the more
advanced animals.
In order to be classified as a chordate an animal must have the following characteristics.
Although it may seem as if many chordates do not possess these characteristics, they
do at some point during embryonic development.
1. Notochord
______________________________
______________________________
______________________________
______________________________
_________________________. The
function of the notochord is to provide
support and protection to the nerve
chord. In the higher chordates, the
vertebrates, the notochord is present
in embryonic development and _____
______________________________
________________________________________________.
2. Dorsal Tubular Nerve Chord
The _____________________________________________________________ is
exactly what its name suggests. The term dorsal means it is on the back side of the
animal. The term tubular means it is hollow. It is the nerve chord of the animal. The
hollow portion of the nerve chord is filled with fluid that nourishes the nerve cells. I_____
______________________________________________________________________
______________________________________________________________________
3. Pharyngeal Pouches
______________________________________________________________________
______________________________________________________________________
. In water-breathing animals the pharyngeal pouches become the gills or gill slits. In air-
breathing animals the pharyngeal pouches take on a number of functions. None of the
pharyngeal pouches are involved in respiration in humans.
4. Post Anal Tail
The ___________________________ is simply an extension of the nerve chord and
body __________________________________________.
There are three sub-phlya that will be discussed in the lessons to follow:
Subphylum Urochordata.
Subphylum Cephalachordata.
Subphylum Vertebrata
Endoskeletons
All of the chordates have an ______________________________. The skeleton of
chordates varies greatly from the ___________________________________________
_________________________________ to the _______________________________
_____________________________ and the bony skeletons of humans.
This endoskeleton possesses advantages and disadvantages to the previously studied
exoskeleton of Arthropods. The endoskeleton doesn't provide the overall protection to
the body that the exoskeleton does. Where protection of a certain internal organ is very
important it is well protected by the endoskeleton. In humans, the skull, spine, and rib
cage would be examples of bones that are providing effective protection for organs like
the brain, spinal cord and heart.
The endoskeleton has a _________________________________________________
______________________. Likely, the most important improvement over the
exoskeleton is its _________________________________. The exoskeleton must be
periodically shed and regrown. This leaves the animal vulnerable for a short time while it
is regrowing its exoskeleton and is also very costly in terms of energy. With the
endoskeleton's ability to grow along with the animal, these animals can grow much
larger and energy can be expended on the development of other organs.
Prochodates
General Characteristics of Prochordates
________________________________________________________________ are
those animals in which _________________________________________________
__________________________________ during development. The two subphyla of
prochordate are the __________________ (subphylum Cephalochordata) and the
_______________________ (subphylum Urochordata).
__________________________ (subphlum Cephalochordata) _________________
______________________________________________________________________
_____________________________________________. The ____________________
______________________________________________________________________
_______________________. A lancelet is very mobile and powers its way through the
water with muscles that
use the notochord as a
point of attachment. The
tentacles around the
mouth are for searching
through mud for
microscopic food particles
that will filter out of the
constant water stream that
is moving through the
animal.
Anatomy of a Lancelet
Tunicates
______________________________________________________________________
___________________________________________________. There are an
estimated 2000 species of tunicates that are commonly called “Tunics” meaning tough
covering. ______________________________________________________________
__________________________________. Tunicates are hermaphrodites.
The adult tunicate (subphylum Urochordata) looks more like an invertebrate than a
chordate since the only
retained trait from the larval
stage are the gill slits.
Tunicate larva possesses all
of the chordate
characteristics. The tadpole-
like larvae is bilaterally
symmetrical and free
swimming which is ideal for
the dispersal stage of the tunicate life cycle. __________________________________
______________________________________________________________________
___________________________. The sessile tunicate will filter feeder by drawing in
water thought its incurrent siphon and past the gill slits to filter out oxygen and food. The
larvaceans (class Appendicularia) are a group of tunicates that remain in the larval form
and do not become the sessile adult. ________________________________________
______________________________________________________________________
______________________________________.
Vertebrates
Diversity of Vertebrates
The anatomy and physiology of humans is the focus of Biology 12. For this reason, the
study of the vertebrates in Biology 11 will be an introduction to the diversity of the
classes within the phylum. The vertebrates are the animals that are more typically used
to represent the chordate phylum. With ______________________________________
______________________________________________________________________
___________________, the vertebrates are the
most advanced of all organisms.
Vertebrates are distinguished from other
chordates by __________________________:
1) ___________________________________
______________________________________
that surround and protect the dorsal nerve cord.
The vertebrae form a vertebral column or spine.
2) A cranium or ________________________
_________________________.
3) An _________________________________
___________________________
Features of Vertebrates
A living endoskeleton with
vertebral column that can grow.
________________________
________________________.
Paired appendages.
Efficient respiration and
excretion.
________________________
________________________.
Adapted to active lifestyles.
Fishes
Vertebrates first appear in the fossil record ___________________________________.
Today there are an estimated 45,000 species of vertebrates. More than 24,000 of these
are fish species. _______________________________________________________.
Class __________________________________
_______________________________________
Class __________________________________
_______________________________________
Class __________________________________
_______________________________________
General Characteristics of Fishes
Fish have a stream-lined shape for to reduce drag with
paired fins that allow movement left or right. Secretion of a
mucus layer helps to reduce friction. Fish have an air
bladder which stores carbon dioxide to control their
buoyancy in the water. Gills allow for gas exchange between the blood stream and
water. Fish also have a lateral line or row of sensory structures along the side of the
body that can detect vibrations in the water.
Jawless Fishes
It is predicted that the ________________________________
__________________________________________________
_______________________ since they are the most similar
to the prochordates and are the oldest known vertebrate fossils. Jawless fishes have
_________________________________________________________________. They
rely on external fertilization for reproduction. Examples of these fishes include the
___________________________________. Both of these fishes rely on symbiotic
relationships.
______________________ are deep sea bottom dwellers named for their slimy coat.
They take part in a commensalistic relationship as _____________________________
_____________________________________________________________________.
__________________
__________________
__________________.
The circular rasping
teeth of the lamprey
attach to a fish.
Rasping at the flesh of
the host fish the
lamprey will feed off of
the blood. Lampreys
are an exotic species introduced into the Great Lakes through the discharge of ballast
tanks from ships. They devastated native fish populations in the 1970's and 1980's.
Cartilaginous Fishes
The next group of fishes are the ___________________________________________
_________________________________. This class includes sharks, skates and rays.
______________________________________________________________________
____________________________________. The cartilaginous fishes are all marine
and all are carnivorous except the whale shark. They have jaws, paired appendages,
visceral arches, three semi-circular canals,
paired nasal cavities, and placoid scales that
feel like sandpaper, and a well developed sense
of smell. As their name suggests they have an
endoskeleton made entirely of cartilage. Other
features include no swim bladder or lung, a
heterocercal or asymmetrical tail, and
respiration by means of five to seven pairs of
gills with gill slits. These fish have separate
sexes and utilize several reproductive
strategies. Some species are oviparous (eggs
hatch outside the body), others are
ovovivparous (eggs hatch inside the body), and
others are viviparous (young are cared for
completely internally).
____________________ have very well
developed senses that are used to locate prey.
In fact, they actually have seven senses. The two extra senses are the ability to detect
slight electric currents in water which could be caused by the muscle contractions of
another animal and the ability to detect changes in pressure in water currents with their
lateral line. Sharks have 6-20 rows of teeth that are continually being replaced and may
use over 20,000 teeth in a lifetime. The paired pectoral fins in sharks are located just
behind the head and jut out from the body like wings on a plane to provide lift when
swimming
.
_________________________________ have flattened bodies, paired wing like
pectoral fins, and some species have a whip like tail. Rays have diamond shaped
bodies while skates have triangular shaped bodies. Both are bottom dwellers and their
flat shape and color camouflage them with the ocean floor.
Bony Fishes
_____________________________________________________________ have a
________________________________________________________________. Bony
fish are characterized by three key features; bone, lungs or swim
bladder, and scales. The tail is usually homocercal or symmetrical on
the top and bottom. They have skin with mucous glands and
embedded dermal scales. The operculum, a bony plate that protects
the gills, is found in bony fishes.
These are the fishes that we generally
think of when we think of fish. From the
fish that we eat to the ones we keep as
pets in a fish tank. One of the most
unique organs in the bony fishes is the
swim bladder. This is a relatively large air
sac within the fish that increases in size
when the fish wants to go up and decreases in size when the fish wants to go down.
Most of the bony fishes are ray-finned fish. However, a very important group of fish in
terms of evolution are the lobe-finned fishes. _________________________________
_______________________________. These
fishes not only had fleshy appendages instead of flat
fins, but they also had a lung that could be used for
respiration. Lobe-finned fish were long thought to be
extinct, but in 1938 a lobe-finned fish called a
coelacanth was caught off the coast of Madagascar.
These are the only known living lobe-finned fish.
Bony fish all have a very similar internal anatomy.
The circulatory system consists of a ____________
_______________________ with separate arterial
and venous systems and four aortic arches. The
nervous system consists of a well developed brain
with well developed olfactory and optic lobes. Most
species are oviparous and fertilization is external.
Life in the Water
Scales found in fishes prevent diffusion through body tissues so gills are needed for gas
exchange. In marine fish water is continually leaving the body by osmosis and ions are
continually entering. To keep from dehydrating they must drink large amounts of water
and produce a small amount of concentrated urine. Their gills are also adapted to lose
salt. In freshwater fish water is continually entering the body of the fish by osmosis so
they do not drink water and produce large amounts of dilute urine.
Amphibians
Amphibians are the most primitive of the animals to possess true limbs and are
tetrapods with four legs. Other features are __________________________________
______________________________________________________________________
_____________________________________________________________________.
Frogs, toads, newts and salamanders all undergo metamorphosis from a ___________
________________________________________________________________.
Amphibians must lay their eggs in a place where they will hatch in water. Respiration
occurs in the __________________________________________________________
_______________________________________________________.
Adaptation to Land
Two Hypothesis:
1) Aquatic vertebrates first moved onto land as shallow pools of water began
drying up. This theory is no longer accepted.
2) More likely that ancestors of amphibians left the water to escape predation,
competition and gain access to the abundance of resources on land.
Characteristics of Early Amphibians
Amphibians _________________________________________. Four strong limbs
developed from fins. The adaptations for living on land included sense organs for
detecting scents and sound. 360-286 million years ago early amphibians split into two
main evolutionary lines that led to modern amphibians and reptiles.
Diversification of Amphibians
Today there are an estimated 4,500 species of amphibians in three Orders. Modern
amphibians share the five key characteristics of metamorphosis, _________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
_____________________________________________________________________.
The Order Anura includes
frogs and toads. They are
found worldwide except in
polar climates. Frogs and
toads live in a variety of
habitats. The term “toad” is
commonly used for any
anuran that has rough bumpy skin. The term “frog” is commonly
used when anurans have smooth moist skin.
Frogs and toads spend part of their life in water (if not all). They are characterized by a
body adapted for jumping and are carnivores (some have a sticky tongue).
Many return to the water to reproduce where their eggs hatch into larvae called
tadpoles.
The Order Urodela includes salamanders that are characterized by elongated bodies,
long tails, and moist skin. Most salamanders have four limbs and are aquatic and
terrestrial. They are carnivores who are mainly active at night.
Most of them live in North America and Central America.
The Family Plethodontidae or ________________________________________ with
more then 300 species is the largest group of salamanders. _____________________
______________________________________________________________________
____________________________________________. Fertilization is internal and they
lay eggs in water (larval stage) or in moist land environments (no larval stage).
The Order Apoda includes caecilian or legless amphibians as the name suggests. They
resemble small snakes and are often blind. Caecilians are
rarely scene and little is known about their ecology and
behavior. Most of them burrow in
soil and some are aquatic. All
species have teeth and eat worms
and other invertebrates that they
detect using chemosensory
tentacles on the side of their head. They can be found in Asia, Africa and South
America.
Reproduction in Amphibians
The reproductive system of the male frog includes two bean shaped testes located near
the kidneys. During the breeding season sperm develop in the testes and pass through
the tubes to the kidneys and urinary ducts. During mating sperm leaves the body
through the _________________________ opening.
The reproductive system of the female frog includes a pair of
large, lobed ovaries containing thousands of tiny immature eggs
that lie near the kidneys. During the breeding season the eggs
enlarge, mature and burst through the thin ovarian walls into the
body cavity. Cilia move the egg forward into a funnel like
opening of the oviducts. As eggs pass through the oviduct they
are coated with jelly like material. The eggs exit through the
cloaca to the external environment where fertilization occurs.
Courtship and Fertilization
In early spring frogs emerge from hibernation and migrate
to ponds and slow moving streams. Males call to attract
females and warn off other males. Each species has its
own mating call. When a mating pair find each other, the
male frog climbs onto the females back in an embrace
called amplexus that may last for days. The female leases
legs into the water and the male discharges sperm over
them called direct external fertilization.
Metamorphosis
Increasing levels of a hormone called thyroxine which
circulates throughout the bloodstream stimulates
metamorphosis. Within a few
days of fertilization tadpoles
emerge. They live off the yolk
stored in their body. Tadpoles
grows larger and develop three
pairs of gills. Eventually the
mouth opens and allows it to
feed. A process of change
called metamorphosis results
in the legs growing and the
tail and gills disappearing.
The mouth broadens and
develops teeth and jaws. The
lungs then become functional.
Parental Care
Parental care is common
among amphibians. Eggs and
larvae are vulnerable to
predators so parental care
increases the likelihood that
offspring will survive. Most often
the male remains with eggs to
guard them. Darwin’s males take young into their mouth.
Female gastric-brooding frogs swallow their eggs. Both
appear to have become extinct !!
Reptiles
Reptiles are ___________________________________________________________
________________________________________ by the Permian period. Reptiles have
a ___________________________________ that is keratinized and ______________
_____________________________________. They are usually tetrapods and have
_____________________________________. Reptiles have evolved to be completely
terrestrial in many cases and are no longer dependent upon water for the laying of
eggs. This is because of the ***_______________________________****. This egg is
developed from ________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
. Reptiles, fish and amphibians are cold blooded or __________________________.
This does not mean that their blood is cold. The body temperature of an ectotherm is
__________________________________________________________________.
Therefore, ectothermic animals regulate their body temperature by regulating their
surroundings. They will lie in the sun if it is cold out,
and shade themselves if they are hot. Ectotherms
must still regulate their body temperature in order for
normal internal body functions to take place.
The image to the right shows the American Alligator,
Garter snake close up, Gopherus polyphemus, and
the Collared Lizard.
Birds
Birds are ______________________. Often referred
to as ______________________________, birds and
other endothermic animals regulate their body temperature internally. By maintaining a
constant internal body temperature bodily functions occur at optimum levels of
efficiency. This self regulation is known as _________________________. This is
important for animals such as birds that require a great deal of energy for flight. Birds
also have other adaptations for flight such as _________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________.
Since we can see a bird’s beak,
we can easily hypothesize what
it might eat. We can watch birds
catch, handle, and swallow
different foods to test our
hypotheses based on the shape
of the bill. The sharp thin bill of
herons and egrets spear fish.
The hooked bills of hawks and
owls grab and rip apart prey and
the short conical bills of sparrows
crack seeds.
Flight is very efficient but requires a lot of energy. Flying birds have 5-20 times their
resting metabolic rate while running mammals only have 2-4 times their resting
metabolic rate. To produce the level of energy required for flight, birds have incredibly
efficient and ___________________________________________________________
_______________________________________________________. These systems
allow both fast flight and long distance migration.
In addition, _________________________
__________________________________
that greatly aid in flight.
_________________________________
_________________________________
_________________________________
_________________________________.
Air passes through bird lungs _________
______________________ into posterior __
___________________________________
______________________ by a different
route. As a result, there are two passes of air in each respiratory cycle and because of
countercurrent flow the oxygen extraction is very high. Birds have a _______________
______________________________________________________________________
________________________________________________________. This efficiency
of respiration and circulation enables birds to fly over the Himalayans at the altitude of
Mount Everest.
Mammals
Mammals are thought to have
evolved during the Mesozoic Era
from therapsids. The mammalian
skull accommodates a larger brain
relative to its body size and
differentiated teeth. Mammals are
characterized by having _________
____________________________
______________________
Mammals have a high level of infant
care, because the young are fed by
means of the mammary glands. The adults must expend a lot of energy in the young,
but it increases the chances of having successful offspring. This high-energy load on
the mother means fewer offspring are produced. Mammals share other characteristics
with birds. For example, efficient circulatory and respiratory systems, a ____________
_______________________ and being _________________________ are
characteristic shared by both. Mammals are divided into three groups; monotremes,
marsupials, and placental mammals.
Monotremes
The ______________________________
_________________________________
_________________________________
_________________________________
_________________________________.
They are different from the other mammals
in that they ________________________
_________________________________
and have a cloaca. Interestingly, the
platypus lacks a true stomach and digests its food in a enlarged area of the esophagus.
Marsupials
Marsupials (like the wombat above) are found
mainly in Australia, but some marsupials are found
in South and Central America as well. The only
marsupial living in North America is the opossum.
These opossums, although not native to the area,
are found as far north as Hornby Island, British
Columbia. In Australia, marsupials have filled many
of the niches held by placental mammals in the rest
of the world. Marsupials spend comparatively less
time with pregnancy and they are born very
immature. Once born they enter a pouch on the mother. Fed by the mammary glands
the newborn will remain in the pouch until mature. The vast majority of marsupial fossils
have been found in Australia including those of a huge ten foot tall kangaroo ancestor.
Placental Mammals
Due to the presence of the _______________________________________________
____________________________________________________________, a longer
pregnancy is possible. The increased gestation time allows more energy to be used for
the development of the nervous system. As a result of this development, placental
mammals have the largest brain to body weight ratio. Even after the lengthy pregnancy
brain development continues under parental care. The larger brain has resulted in social
development and communication in many mammals. Placental mammals are very
widely distributed around the world and have members in almost every niche. Bats have
taken to the air, whales to the water, and many examples exist on land. Placental
mammals can be _______________________________________________________.
Major Orders of Placental Mammals
Perissodactyla - Horses.
Artiodactyla - Deer.
Carnivora - Cats.
Primates - Monkeys.
Cetacea - Whales.
Chiroptera - Bats.
Rodentia - Mice.
Proboscidea - Elephants.
Lagomorpha - Rabbits.