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.