kingdom animalia: phylum chordata
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Kingdom Animalia: Phylum Chordata
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Phylum Chordata: animals with a chord Unique combination of four characteristics present at some stage in development:
- notochord (support rod, replaced by backbone in vertebrates)
- nerve cord (spinal cord)
- pharyngeal slits (feeding and/or gas exchange)
Each arch develops its own artery, nerve that controls a distinct muscle group, and skeletal tissue.
- Muscular post-anal tail (extension beyond anus, later reduced)
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Subphylum Urochordata: sea squirts or tunicates
Larva is free swimming and adult is sessile
Notochord, nerve cord, and postanal tail present during _________
Pharyngeal slits present in ________
Subphylum Cephalochordata: lancelets (Amphioxus)
- NEW feature is a brain
- Body shaped like a surgical knife
- All 4 chordate characteristics persist throughout life
-Marine, buried in sand and filter feed
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Class Myxini: Hagfish - Lack jaws and paired appendages
- Cartilaginous skeleton
- Notochord present
- Skin without scales
- mouth with tentacles
- mucous glands for defense
- NEW FEATURE: cranium (skull), but no vertebrae
hagfish are not vertebrates
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Subphylum Vertebrata: animals with vertebrae
- Four chordate characteristics present in embryonic states:
1 - notochord (at least in the embryo)
A vertebral column replaces the notochord
possess a distinct skull (cranium) enclosing the brain
2 - pharynx with pouches or slits in wall (at least in the embryo)
region of alimentary canal exhibiting pharyngeal pouches in embryo
pouches may open to the exterior as slits:
permanent slits - adults that live in water & breathe via gills
temporary slits - adults live on land
3 - dorsal, hollow nervous system
4 – post anal tail
Class Petromyzontida: Lampreys - sucking mouth with teeth and rasping tongue
- There have always been native freshwater lampreys in North American waters. But since 1835,
They have been spreading through manmade canals into the Great Lakes of northeastern North America
In the 1940s and 1950s, the sea lamprey caused serious damage to the fisheries of the Great Lakes.
It is now the subject of control efforts by U.S. and Canadian government
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Evolution of jaws The evolution of jaws is an example of evolutionary modification of existing structures to perform new functions.
Pharyngeal slits in tunicates and lancelets where used mainly for feeding
Theses slits have skeletal rods supporting them
First and second skeletal rods became the jaws. Advantage of jaws?
Gills became less important for filter feeding and
more important in gas exchange
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Class Chondrichthyes: sharks ,rays, and skates - Cartilaginous skeleton
- They have five to seven gill slits
and lack the gill cover (operculum found in bony fish)
- Lack swim bladder or lungs
- Body is covered tooth like scales (derived from mesoderm)
Developmental studies show the teeth of sharks are enlarged scales
- Paired fins
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Bony fish (Osteichthyes) Cartilage is replaced by bone during development
Single gill opening covered by an operculum
Scales derived from
mesoderm , like rooftiles
Pectoral and Pelvic fins
Are homologous to our limbs
Two Classes:
Actinopterygii: Ray-fin fish
Dominant class of vertebrates, ½ sp.
Swim bladder for buoyancy
Sarcopterygii: Lobe-fin fish
Fleshy fins with bony, leg like support
swim bladder for buoyancy and gas exchange
Coelacanths, lung fish,
and ancestors to tetrapods
The evolution of Lungs
Lungs and swim bladders: form during development as an out pocket of the gut
The common ancestor of the lobe- and ray-finned fishes had lungs as well as gills. In the lobefins, lungs stuck around, and tetrapods, coelacanths, and (duh) lungfish, all inherited them and use them to obtain oxygen. The ray-finned fishes lungs evolved into the swimbladder — a gas-filled organ that helps the fish control its buoyancy.
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Move on to land: weight bearing appendages
Tiktaalik
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Class Amphibia: Frogs, toads, salamanders
- Undrego metamorphosis
- Characteristics of a land animal:
- Characteristics of an aquatic animal:
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Note that the largest and most conspicuous organ is the liver (1), which is divided into three lobes. Located between the right and left lobes of the liver is the gall bladder (2), which stores bile (a digestive juice) that is produced by the liver. When needed for digestion, the gall bladder secretes a small amount that aids in the breakdown of food, specifically fats. Structures belonging to the digestive system that can be seen include the stomach (3), small intestine (4) and large intestine (5). Other labeled structures include the bright orange or yellow fat bodies (6) that provide enough energy for a frog or toad to go without food during hibernation or estivation (burrowing to escape summer heat and arid conditions) for over a year, the heart (7) and deflated urinary bladder (8).
Amniotic Egg: reproductive freedom from water
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Class Repitlia: snakes, lizars, alligators, turtles - Dry skin with epidermal scales with keratin
- Internal fertilization
- Amniotic egg
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Class Aves: Bird - Feathers
- Skeleton modified for flight
Sternum bears a large keel to anchor flight muscles
- Endothermic
- Amniotic egg
- Internal fertilization
Although teeth look very different from hair, nails or sweat glands, teeth share a deep evolutionary history with these and other parts of our anatomy. The shared origin of these body parts is reflected in their strikingly similar development. They also share a common set of genetic instructions, including the master regulator gene EDA. EDA also controls the development of skin features in many other animals, including fish, suggesting that these features' history is ancient.
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Class Mammalia: mammals Monotremes : Platypus and Echidna
Marsupials: kangaroo, koala, opossums
Placentals:
What are the characteristics of ALL mammal?
Placentals Placenta is a modified egg:
The embryo is still surrounded by an amnion filled with amniotic fluid
The allantois and yolk sac become the umbilical cord
providing a connection through which food reaches the fetus, and wastes are removed.
Around the whole is the fluid-filled chorion, which "breaks" as labor begins.
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Order Lagomorpha: rabbits, hares and picas
Chisel-like incisors, hind legs longer than forelegs, jumping
Order Rodentia: squirrels, beavers, rats, porcupines, mice
Chisel- like continuously growing incisors, herbivorous
Order Carnivora: dogs, bears, cats, seals, walruses
Sharp, pointed canine teeth and molars for shearing, carnivorous
Order Artiodactyla: sheep, pigs, cattle, deer, giraffes
Hooves with an even number of toes on each foot; herbivorous
Order Cetacea: whales, dolphins and porpoises
aquatic; blubber; carnivorous
Order Perissodactyla: Horses, zebras, tapirs, rhinoceroses
Hooves with an odd number of toes on each foot; herbivorous
Order Primates: lemurs, monkeys, apes, humans
Opposable thumbs; forward-facing eyes; omnivorous
Order Chiroptera : bats
Winged mammals that use echolocation for navigation
Important Chordates Sea squirt cancer drug under test
Scientists seek sea squirts by the seashore Harvard University Gazette, 5/23/2002
In the United States, researchers at three Harvard University-affiliated hospitals -- Massachusetts
General Hospital, Dana-Farber Cancer Institute, and Brigham and Women's Hospital -- have been
testing a powerful drug on patients with breast, ovarian, and prostate cancer. "Tests show that the
drug has been active enough to expand these trials," says Bruce Chabner, a professor of medicine
at Harvard Medical School. The drug comes from sea squirts, tunicates that filter food particles
from ocean water with the help of two siphonlike openings at the top. The drug derived from sea
squirts is so incredibly powerful, only 0.05 ounce is enough to treat 100 patients. According to Elias
J. Corey, Sheldon Emery Professor of Chemistry at Harvard, a mere 11 pounds of the drug would
satisfy world demand for about a year. It's good that it is so powerful, because a harvest of about
95,000 pounds of sea squirts yields a scant 3 ounces of the drug. Two years ago, Corey managed
to make the drug synthetically. A Spanish company, PharmaMar, has established an underwater
farm on which the tubelike creatures are being raised.
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Important Chordates Lampreys have long been used as food for humans. During the Middle Ages, they were widely
eaten by the upper classes throughout Europe, especially during fasting periods, since their taste is
much meatier than that of most true fish. King Henry I of England is said to have died from eating
spoiled lampreys.
Especially in Southwestern Europe (Portugal, Spain, France) they are still a highly prized delicacy
and fetch up to $25 a pound. Overfishing has reduced their number in those parts.
On the other hand, lampreys have become a major plague in the North American Great Lakes after
artificial canals allowed their entry during the early 20th century. They are considered an invasive
species, have no natural enemies in the lakes and prey on many species of commercial value, such
as lake trout. Since North American consumers, unlike Europeans, refuse to accept lampreys as
food fish, the Great Lakes fishery has been very adversely affected by their invasion.
Important Chordates Poison From Frog Skin Leads to a Painkiller
Taking a clue from a deadly poison found in the skin of a South American frog, researchers have
discovered a powerful painkiller that seems to have all of the benefits of morphine, but none of the
damaging side effects.
Researchers at Abbott Laboratories in North Chicago, Ill., developed the new painkiller, called ABT-
594, after scientists at the National Institutes of Health isolated a poison from the skin of a species
of Ecuadorean frog, Epibpedobates tricolor.
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Important Chordates Diabetes drug stems from Gila monster spit
Published April 30, 2005
WASHINGTON - Scientists have found a surprising use for the saliva of a desert lizard.
Gila Monster spit is being tested as a treatment for type-2 diabetes, the most common
form of the affliction.
The Food and Drug Administration approved Byetta, known chemically as exenatide, the
first in a new class of medications for Type 2 diabetes.
Important Chordates Mice are convenient in research because their physiology is similar to that of humans
(though rats are a better models for certain diseases) and their short life cycle makes
breeding easy. They are mainly used to model human diseases in order to develop new
drugs, to test the safety of proposed drugs, and in basic research.
Over the past century, various fields that deal with life sciences have used mice as model
organisms, and revolutionized the scientific world. Because of their genetic and physiological
similarities to humans, even research areas such as organ transplantation cannot be
separated from use of mice. Like humans, mice can have diseases such as cancer,
arteriosclerosis, hypertension, and diabetes. Also, diseases that are almost unique to
humans such as Alzheimer’s disease can be induced in mice. Therefore, studying molecular
mechanisms such as immune system, cell cycle is also very effective using mouse as a
model organism.