Download Station 1 - El Camino College

5/25/2010
Station 1: Introduction to Phylum Echinodermata
Echinoderms are named for their spiny surfaces. There are 6000 species of
echinoderms; all species are marine. Most are sessile or slow moving.
The Phylum Echinodermata includes the sea urchins, sea stars, sea cucumbers,
and starfish.
The body of an echinoderm lacks body segments, and most have radial symmetry
as adults. Both the external and the internal parts of a sea star, for example,
radiate from the center like spokes of a wheel. In contrast to the adult, the larva of
echinoderms is bilaterally symmetrical. This supports other evidence that
echinoderms are not closely related to cnidarians or other radial animals that
never show bilateral symmetry.
Echinoderms are coelomete animals. During their embryonic development,
coelom forms from an in-folding of the digestive tract (endoderm).
Use this information to answer the questions on your handout
Sea star
Sea urchin
Sea cucumber
Brittle star
Sand dollar
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Station 2: Structure of an echinoderm
The adult body usually has five-part organization.
In the figure of a sea star below, there is a central disc with 5 arms.
Echinoderms possess an internal skeleton (endoskeleton) composed of hard
plates just beneath the surface of the skin. The plates often have bumps and
spines that protrude through the skin and give the animal the prickly surface. The
spines are used for protection, for moving, and for trapping drifting algae to eat.
Unique to echinoderms is the water vascular system: a system of canals and tube
feet filled with sea water that allows the animal to move. Water enters the system
by the madreporite. Each tube foot has a fleshy bulb or ampulla attached so that
the entire structure (ampulla and tube foot) looks like an medicine dropper or
pipette. When muscles surrounding the ampulla contract, fluid inside the bulb
moves down into the tube foot, extending it. The tube feet attach to the surface
and allow for locomotion.
Use this information complete the chart on station 3 on your handout
Skin
Anatomy of a mollusk
endoskeleton
In the figure of sea star on your handout, label the following:
Anus, madreporite, spines, gills, ampulla, tube feet, endoskeleton and skin
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Station 3a: Diversity of Echinoderms
Sea stars (also known as starfish) are spiny, hard-skinned animals that live on the
rocky sea floor. These invertebrates are NOT fish; they are echinoderms. Sea
stars move very slowly along the sea floor, using hundreds of tiny tube feet.
There are over 2,000 different species of sea stars worldwide.
Sea stars are composed of a central disk, usually with five or a multiple of five arms
(rays) extending outward. The mouth is located in the bottom of the central disk
and the anus is located in the top side of the central disk close to the
madreporite.
They feed on bivalves (clams) by pulling apart the shell and lowering their stomach
into the mollusk, releasing enzymes and digesting the mollusk, then absorbing
the digested material into the body of the starfish, where digestive glands in
each arm continue the process of food breakdown.
Fill out the chart
Sketch the top view of one of the example specimens of sea stars and label:
arms, spines and madreporite
Sunflower star
Purple star
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Station 3b: Diversity of Echinoderms
The brittle star (also called the serpent star) is a spiny, hard-skinned, long-armed
animal that lives on the rocky sea floor, from shallow waters to great depths.
Brittle stars are NOT fish, but are related to sea stars. These echinoderms move
very slowly along the sea bed. There are over 2,000 different species of brittle
stars worldwide.
Most brittle stars have five (or a multiple of five) long, thin, spiny arms that radiate
from a flat central disk; the arms do not touch each other at their bases. Brittle
stars that have multiple-forked arms are called basket stars.
Brittle stars are mainly detritivores (detritus-eaters); they eat decaying matter and
plankton. Their mouth is located on the underside of the disk of the brittle stars.
Fill out the chart
Sketch the top view of one of the example specimens of brittle and label:
arms, central disk
Close up of brittle star, note that the
arms do not touch at their bases where
they attach to the central disk
Brittle baskets have
branched arms
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Station 3c: Diversity of Echinoderms
The sea urchin is an echinoderm that lives on the rocky seafloor, from shallow
waters to great depths. These globe shaped echinoderms move very slowly
along the sea floor. There are about 700 different species of sea urchins
worldwide. Many sea urchins have venomous spines.
Adult sea urchins have five-sided radial symmetry. Sea urchins have a globular
body and long spines that radiate from the body. The spines are used for
protection, for moving, and for trapping drifting algae to eat. Among the spines
are five paired rows of tiny tube feet with suckers that help with locomotion,
capturing food, and holding onto the seafloor.
Sea urchins eat plant and animal matter, including kelp, decaying matter, algae,
dead fish, sponges, mussels, and barnacles.
Fill out the chart
Sketch a skeleton of a sea urchin and a sea urchin with spines
Top view of sea urchin skeleton
Sea urchin showing
tube feet
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Station 3d: Diversity of Echinoderms
Sea cucumbers are cylinder-shaped echinoderms that live in seas worldwide. They
are found in a variety of sea floor habitats, from warm tropical waters to cold deep
sea trenches. These nocturnal animals have a life span of about 5 to 10 years.
The body of the sea cucumber is elongated, leathery and muscular; spines are
contained with the skin. These echinoderms have no arms, but do have five-part
symmetry. Surrounding the mouth are 8 to 30 tentacles (modified tube feet). Five
double rows of tube feet (with tiny suction cups) run along the body; they are used
for crawling along the sea bed or anchoring to a rock.
Sea cucumbers eat decaying matter that floats in the water or in the sand.
Fill out the chart
Sketch a preserved sea cucumber label tentacles and tube feet along the body
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Station 3e: Diversity of Echinoderms
The Sand Dollar is an echinoderm that is shaped like a coin (a flattened disk). There
are many different species of sand dollars. They live on the sandy sea floor, from
the intertidal zone (the area between high tide and low tide) down to the subtidal
zone (the area below low tide). Sand dollars partly bury themselves under the
sand, with an edge poking up out of the sand. You can often find the skeletons of a
sand dollar washed up on sandy beaches. If you break open the skeleton, there
are many hard, loose, white pieces; these were the teeth of the Sand Dollar.
Sand Dollars have 5-part radial symmetry. The bottom surface contains the mouth,
many black spines (which trap food), and the cilia (small hairs) that help direct food
into the mouth. Sand Dollars have tiny tube feet that are used as gills.
Sand Dollars eat tiny particles of food that float in the water.
Fill out the chart
Sketch the skeleton of a sand dollar
Close up of sand dollar showing
spines and tube feet
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Station 4a: Importance of Echinoderms
Research on echinoderms has contributed to the overall knowledge of animal fertilization and embryo
development.
The sea urchin occupies a special place in biology due to its long-time use as a standard subject for studies in
embryology. The sea urchin, particularly Arbacia punctulata, is the source of textbook descriptions of "the"
egg, "the" embryo, and their early development. At the Marine Biological Laboratory at Woods Hole, the
Arbacia egg achieved almost the status of a standard "living cell" for physiological, biochemical and
cytological work—resulting, of course, in overfishing and, in 1945, the near-extinction of the local Arbacia
population.
Stages of sea urchin embryo development
Sea urchin spawning
Fill out the chart
Station 4b: Importance of Echinoderms
Humans consume the reproductive organs ("roe") either raw or briefly cooked. Sea
urchin roe is a popular food in Korean cuisine, and it is called "uni" in Japanese
sushi cuisine. It is also a traditional food in Chile, known as an "erizo". Apart from
domestic consumption, Chile and a number of other countries export the sea
urchin to Japan in order to meet its demand throughout the country. Traditionally
roe is considered an aphrodisiac.
Showing gonads “roe” of a sea urchin
Uni, sea urchin roe, in sushi
Fill out the chart
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Station 4c: Importance of Echinoderms
Sea cucumber is one of the strangest foodstuffs in Chinese cuisine. It is highly valued for its
supposed medicinal properties. The flesh of the animal is "cleaned" in a process that takes
several days. Trepang is often purchased dried, and rehydrated before use. The product is
used in Chinese stews and braised dishes due to its gelatinous texture. In Japanese cuisine,
Konowata is made of cured sea cucumber entrails which are extracted, salted, and cured. It
is considered a major delicacy in Far East countries such as Malaysia, China, Japan, and
Indonesia.
Prepared sea cucumber in oyster sauce
Fill out the chart
Station 5: Introduction to Phylum Chordata
Chordates are animals that occupy every environment in the world. Their bodies
exhibit bilateral symmetry. They are coelomete animals. During their embryonic
development, coelom forms from an in-folding of the digestive tract (endoderm).
There are 47,200 species of chordates that have been described.
There are three subphyla of Chordates: Tunicates, Lancelets, Vertebrates.
Tunicates and lancelets are invertebrates but most chordates are vertebrates.
Use this information to answer the questions on your handout
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Lancelet
Tunicate
Station 6: Structure of a chordate
Our Phylum Chordata includes two subphyla of invertebrates, animals without a backbone:
lancelets and tunicates. These invertebrate chordates and vertebrates all share four key
features that appear in the embryo and sometimes in the adult. These four chordate
hallmarks are:
1. a dorsal, hollow nerve chord (the chordate brain and spinal cord)
2. A notochord, which is flexible, longitudinal rod located between the digestive tract and
the nerve cord
3. Pharyngeal slits or gill slits, which are gill structures in the pharynx, the region of the
digestive tube just behind the mouth
4. A post anal tail, which is a tail to the rear of the anus.
Though these chordate characteristics are often difficult to recognize in the adult animal,
they are always present in the chordate embryos. For example, the notochord, for which
our phylum is named, persists in adult humans only in the form of the cartilage disks
that function as cushions between the vertebrae.
Use this information complete the chart on station 7 on your handout
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Characteristics of all chordates
In the figure of sea star on station 7 of your handout, label the following:
Mouth, anus, brain, nerve chord, notochord, pharyngeal slits, pots anal tail
Station 7: Introduction to subphylum Urochordata
The subphylum Urochordata contains 1,250 species of tunicates that have gill slits.
Adults have a body composed of an outer tunic (hence the name tunicates) with two siphons. The
only chordate characteristic that remains in adults is the pharyngeal slits. On the other hand, the
larva of a tunicate is bilaterally symmetrical and has the four chordate characteristics. The free
swimming larva (tadpole looking) will undergo metamorphosis and turn into a sessile adult.
In adult tunicates, the siphons are used to bring water in and out. Water passes into the pharynx
and out numerous gill slits. Microscopic particles adhere to a mucous secretion in the pharynx and
are eaten.
When they are disturbed, tunicates tend to squirt water out (hence tunicates are also called sea
squirts).
Use this information to answer the questions for station 9 on your handout
Sketch a preserved tunicate and
one of the pictures of tunicate below and label the two siphons
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Adult tunicate showing anatomy
Tunicate larva
Metamorphosis of a tunicate
Pictures of different tunicates
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Station 8: Introduction to subphylum Cephalochordata
The lancelets have all the chordate characteristics. The 23 species of lancelets are in
the genus Branchiostoma in the subphylum Cephalochordata. Their elongated, lanceshaped body resembles the lancelet, a two-edged surgical knife. They inhabit shallow
coastal waters; they lie partly buried in sandy substrates and filter feed. Lancelets feed
on microscopic particles filtered from the constant stream of water that enters the mouth
and exits through the pharyngeal slits. Lancelets retain all the chordate characteristics
as an adult. The notochord extends from head to tail, accounting for the name
"Cephalochordata.“
Use this information to answer the questions for station 10 on your handout
Sketch a preserved lancelet
Lancelet
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Station 9: Introduction to subphylum Vertebrata
The notochord of vertebrates is generally replaced by a vertebral column composed of numerous
small bones called vertebrae that are joined together to form a flexible supporting structure.
The vertebral column allows the body to flex and provides attachment sites for muscles. In addition,
it surrounds and protects the nerve cord.
Vertebrates exhibit extreme cephalization (big brains) and possess complex sense organs (ex:
eyes, ears). The brain is enclosed and protected by a skull.
The nerve cord is the one chordate feature present in the adult phase of all vertebrates. The
vertebrate skeleton is living tissue (either cartilage or bone) that grows as the animal grows.
Subphylum Vertebrata includes the following classes:
Class Agnatha: jawless fishes
Class Chondrichthyes: cartilaginous fishes (sharks and rays)
Class Osteichthyes: bony fishes
Class Amphibia: amphibians (frogs, toads and salamanders)
Class Reptilia: reptiles (turtles, snakes, lizards, crocodiles)
Class Aves: birds
Class Mammalia: mammals
Use this information to answer the questions for station 11 on your handout
Vertebrates: chordates with a backbone (vertebra)
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Station 10: Class Agnatha
The earliest vertebrate fossils were jawless filter-feeding fish from the Ordovician
(early Paleozoic). They had heavy bony armor and were probably filter feeders
much like the invertebrate chordates.
Living species living species of jawless fish include hagfish (scavengers) and
lampreys (some are parasitic).
These long, eel-like, jawless fish are free-swimming predators on other fish. They
use their jawless mouths as suckers to attach to the sides of large fishes and draw
blood.
Lampreys hatch in freshwater and many live their lives entirely in freshwater. Some
lampreys migrate to the sea, but must return to freshwater to reproduce.
Lampreys have a sucker-like mouth that lacks a jaw.
Use this information to answer the questions
Sketch a lamprey and label mouth and gill slits
Adult and juvenile lamprey
showing jawless mouth
Lamprey parasite of trout
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Station 11: Jaws
The evolution of jaws is an example of
evolutionary modification of existing structures to
perform new functions. Jaws are modified gill
arches. Jaws enabled fish to switch from filterfeeding to predation and thus promoted an
active life style.
Filter feeding by pharyngeal slits or gill slits
became less important with the evolution of jaws
because jaws allowed the animal to chew larger
food items and to capture prey.
Gills became more important in gas exchange.
There are two classes of jawed fish: the
cartilaginous fish and the bony fish.
Use this information to answer the questions
Station 12: Class Chondrichthyes
The class Chondrichthyes contains approximately 850 species of skates, rays, and sharks. They
have jaws, lots of teeth, paired fins, and a cartilage endoskeleton.
These fish have five to seven gill slits on both sides of the pharynx, and lack the gill covers found in
bony fish.
The bodies of cartilaginous fish are covered with small toothlike scales. Their teeth are larger
versions of these scales. They do not have a swim bladder but the oil-storing capacity of their livers
improves their buoyancy.
Some sharks are fast-swimming predators; others are filter feeders. Rays live on the ocean floor;
their pectoral fins are enlarged into winglike fins; they swim slowly. Stingrays have a venomous
spine. The electric ray family can feed on fish that have been stunned with electric shock of over
300 volts.
Sharks and rays reproduce by eggs. Mermaid's purses is the name given to the empty egg cases of
sharks, skates and rays. They are among the objects which are washed in by the sea, and can be
found when walking on the beach. The color and shape of mermaid's purses also varies greatly
from species to species. The young fish would normally incubate between 6-12 months.
Use this information to answer the questions
Sketch a preserved shark and ray. For each label pectoral fins, mouth and gill slits.
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Whale sharks are the largest fishes (45 feet)
And are filter feeders
Mermaid purses: Shark eggs
Some rays are social and live in groups
Bat ray
Bottom view showing gill slits of ray
Eggs of ray
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Station 13: Class Osteichthyes
The Class Osteichthyes includes bony fishes that have a skeleton reinforced by hard calcium
(bone). The gills are covered by an operculum so that the gills are protected. Movement of the
operculum allows the fish to breathe without swimming (by contrast, Chondrichthyes lack the
operculum and must swim to pass water over their gills). The skin of bony fishes is covered by
scales formed of bone.
Bony fishes also have a specialized organ that helps keep them buoyant called the swim
bladder, which is a gas filled sac. Thus, many bony fishes can conserve energy by remaining
almost motionless, in contrast to sharks, which sink to the bottom if they stop swimming.
Bony fishes have external fertilization. Fish, are ectothermic; they depend upon external heat
(by sunning) to regulate body temperatures.
There are about 20,000 species of bony fish, found both in marine and freshwater.
Use this information to answer the questions
Sketch a preserved bony fish. Label pectoral fins, mouth and operculum.
Sketch a sea horse and label pectoral fins, mouth and operculum.
The largest fish is the oarfish that can
measure up to 40 feet long
Sea horse is a fish
operculum
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Station 14: Class Amphibia
Frogs, toads, salamanders are amphibians.
Amphibians are tied to the water. Amphibians have small inefficient lungs and most species also
use their skin for respiration. Because the skin is used in gas exchange, it must remain moist, so
amphibians can not venture far into very dry habitats. Nor do they have any body cover like scales,
hair or feathers.
Amphibians must reproduce in water because: they have external fertilization and sperm require
water to swim. The eggs do not have an outer covering or shell and therefore are not protected
against desiccation.
The larvae (tadpoles) are aquatic and use gills for respiration.
Amphibians where the first vertebrates to colonize land. They descended from fishes that had lungs
and fins with muscles and skeletal supports strong enough to enable some movement on land.
Amphibians, like fish, are ectothermic; they depend upon external heat to regulate body
temperatures. If the environmental temperature becomes too low, ectotherms become inactive.
Use this information to answer the questions
Sketch a preserved amphibian.
Frog
Salamander
Toad
tadpole
Immature frog
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Station 15: Class Reptilia
Turtles, crocodiles, alligators, lizards, and snakes are reptiles.
They arose from amphibians during the Paleozoic but dominated during the Mesozoic.
Reptiles have more efficient lungs than amphibians.
Reptiles do not need to use their skin for gas exchange because the lungs are sufficient. They have a thick, scaly
skin made of keratin (same protein that our hair is made of) that makes it impermeable to water.
Internal fertilization allows animals to mate without having to be in water.
The eggs are encased in leathery shells to protect them from desiccation. This eliminates the need for a swimming
larval stage.
Reptiles are ectothermic; they depend upon external heat to regulate body temperatures.
Snakes and lizards live mainly in the tropics and deserts. Lizards have four clawed legs and are carnivorous;
marine iguanas on the Galapagos are adapted to spend time in the sea and blind worm lizards live underground.
Snakes evolved from lizards and lost their legs as an adaptation to burrowing. Their jaws can readily dislocate to
engulf large food. Some poisonous snakes have special fangs for injecting their venom into their prey.
Turtles have a heavy bony plates fused to the ribs and vertebrae; this is an adaptation against predators.
Crocodiles and alligators are largely aquatic, feeding on fishes and other animals. They both have a muscular tail
that acts as a paddle to swim and a weapon.
Use this information to answer the questions for station 17 on your handout
Sketch the live California dessert tortoise.
Crocodile
The “shell” of a turtle or tortoise is a
bone plate connected to the backbone
Snake skeleton showing an extra
long back bone, many ribs up to
200 and no legs
Horned lizard
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Station 16: Class Aves
The class Aves (birds) contains about 9000 species. Birds evolved from either a dinosaurian or other reptilian
group during the Jurassic (or possibly earlier). The earliest bird fossils, such as the Jurassic Archaeopteryx
display a mosaic of reptilian and bird features (scales on their feet, teeth in the bill, a tail, and claws on the wing
are reptilian; feathers and hollow bones are bird-like).
Feathers are modified reptilian scales. They insulate against heat loss and allow birds to maintain their body
temperature by internal control, something that fish, amphibians and reptiles can not do. For this reason birds
are considered endothermic, they use the heat produce from their metabolism to regulate their internal
temperature. This internal temperature regulation allows them to be active when the environmental temperature
is low. Reptiles and amphibians depend on the external environment for temperature regulation, so they can
not be active during the cold.
Birds have internal fertilization and produce hard-shelled amniotic eggs.
Modern birds have adapted to all modes of life: flying (condors, eagles, hummingbirds), flightless-running
(ostriches, emus), and swimming (penguins).
Use this information to answer the questions for station 18 on your handout
Sketch one of the preserved birds that are mounted around the lab.
Archaeopteryx showing reptile and
avian characteristics
Hummingbirds flap their
wings 55 times per second
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Station 17: Class Mammalia
Class Mammalia contains around 5000 species. The 2 unifying mammalian characteristics are:
1. hair
2. the production of milk by mammary glands
Milk is a substance rich in fats and proteins. Mammary glands usually occur on the ventral surface of females in
rows (when there are more than two glands). Humans and apes have two mammary glands (one right, one left),
while other animals can have a dozen or more. All mammals have hair at some point during their life. Mammalian
hair is composed of the protein keratin, just like the feathers of birds and the scales of reptiles. The main function
of hair is to insulate the body and help maintain a warm, constant internal temperature; mammals, like birds, are
endotherms, they use the heat produce from their metabolism to regulate their internal temperature.
Mammals first evolved from the mammal-like reptiles during the Triassic period, about the same time as the first
dinosaurs. However, mammals were minor players in the world of the Mesozoic, and only diversified and became
prominent after the extinction of dinosaurs at the close of the Cretaceous period.
Mammals have since occupied all roles once held by dinosaurs and their relatives (flying: bats; swimming: whales,
dolphins; large predators: tigers, lions; large herbivores: elephants, rhinos), as well as a new one (thinkers:
humans).
Use this information to answer the questions for station 19 on your handout
Sketch one of the preserved mammal.
Mammals
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Station 18: Groups of mammals
There are three major groups of mammals: the Monotherms, the marsupials and the
placental mammals.
1. The duck billed platypus is one of only three species of monotremes, the egg-laying
mammals. The platypus female lays two eggs, and incubates them in a leaf nest. After
hatching, the young nurse by licking up milk secreted onto the mother’s fur. The
echidnas are also monotherms.
2. Marsupials are the pouched mammals, including kangaroos, koalas and opossums.
These mammals have a brief gestation an give birth to tiny, embryos that complete
development while attached to the mother’s nipples inside a pouch on the mother’s
abdomen.
3. Placental mammals have a longer period of gestation inside the mother. The embryos
develop in the placenta, that consist of embryo and maternal tissues. The embryo is
nurtured by maternal blood that flows close to the embryonic blood system in the
placenta. Dogs, cats, rabbits, bats, whales and humans are all examples of placental
mammals.
Use this information to fill out the chart on station 20
Platypus is an egg laying mammal
(Monotremes )
Whale, placental mammal, nursing
Kangaroo is a marsupial mammal
Human, placental mammal, nursing
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Station 19a: 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.
Use this information to fill out the chart
on station 21
Station 19b: Important Chordates
Poison From Frog Skin Leads to a Painkiller
Published: January 2, 1998 by the New York Times
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 ABT594, after scientists at the National Institutes of Health isolated a poison from the skin of a species
of Ecuadorean frog, Epibpedobates tricolor.
Use this information to fill out the chart
on station 21
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Station 19c: 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.
Use this information to fill out the chart
on station 21
Station 19d: 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.
Use this information to fill out the chart
on station 21
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Station 19e: Important Chordates
Cover Study Of Nature Provides Startling New Evidence That Only 10% Of All Large
Fish Are Left In Global Ocean
May 15, 2003
The cover story of the May 15th issue of the international journal Nature reveals that we have only 10% of
all large fish--both open ocean species including tuna, swordfish, marlin and the large groundfish such as
cod, halibut, skates and flounder--left in the sea. Most strikingly, the study shows that industrial fisheries
take only ten to fifteen years to grind any new fish community they encounter to one tenth of what it was
before.
"From giant blue marlin to mighty bluefin tuna, and from tropical groupers to Antarctic cod, industrial
fishing has scoured the global ocean. There is no blue frontier left," says lead author Ransom Myers, a
world-leading fisheries biologist based at Dalhousie University in Canada. "Since 1950, with the onset of
industrialized fisheries, we have rapidly reduced the resource base to less than 10% -- not just in some
areas, not just for some stocks, but for entire communities of these large fish species from the tropics to
the poles.“ Their depletion not only threatens the future of these fish and the fishers that depend on them,
it could also bring about a complete re-organization of ocean ecosystems, with unknown global
consequences."
Use this information to fill out the chart
on station 21
And list the species of fish that you should avoid buying because of being overfished
List of seafood to avoid due to overfishing or pollution
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Station 21f: 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.
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