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Deuterostome
Characteristics
of deuterostomes
Deuterostomes phyla
Characteristics of the echinoderms
They develop from
bilaterally symmetrical larvae that metamorphose into radially symmetrical, or
in some cases into bilaterally symmetrical, adults (if the latter, they pass
through a radially symmetrical stage first). Their radial symmetry is
generally pentaradiality — based on five equal divisions of the body, like
five slices of a pie.
They possess a characteristic series of
internal fluid-filled body spaces or cavities, surrounding the viscera, that
are lined by epithelia derived from the embryonic tissue layer that gives rise
to adult muscle and connective tissue. One of these cavities has become
modified for food collection and locomotion, and consists of a series of
tubes, valves and extensible components called tube feet. This, the
hydrovascular or ambulacral system, is found only in echinoderms. Generally,
the tube feet face toward the substrate.
Echinoderms have a calcium carbonate
endoskeleton composed of skeletal plates called ossicles found in the body
wall. With the exception of those comprising the spines of pencil urchins, all
skeletal plates in echinoderms are covered with tissue
Structures are involved to help echinoderms accomplish the following
task
Process |
Structures
Involved |
Respiration |
A Echinoderm uses
some of the bumps or spines on its surface to take in oxygen. It has a
gill structure to take in the oxygen. It has a poorly developed
respiratory system. |
Ingestion |
Mouth, esophagus |
Digestion |
Cardiac stomach,
pyloric stomach, short intestine, digestive glands |
Support |
Spiny-skinned,
endoskeleton of calcium
carbonate |
Reproduction |
A Echinoderm is a
male or female. The males and females discharge their eggs and sperm
into the water where they are fertilized. A female can release one
hundred million eggs at once. If a piece of certain echinoderms is
chopped off, a new piece or even a new echinoderm can re-grow. |
Movement |
Hundreds of tube
feet, small hollow tubes each tipped with a suction disc, and powered by
the water vascular system |
Four chordate characteristics.
·
A notochord, a dorsal supportive rod
extending the length of the body. The
notochord is replaced during development by a vertebral column in the
vertebrates.
·
A dorsal tubular nerve cord.
In vertebrates, the nerve cord, more
often called the spinal cord, is protected by vertebrae.
·
Pharyngeal pouches,
which become functioning gills in the invertebrate chordates, the fishes, and
amphibian larvae. In terrestrial animals, the pouches are modified for various
other functions.
·
A postanal tail – as an embryo if not
as an adult – a tail that extends beyond the anus.
Diverstiy of Chordates
Name
of organism |
Subphylum |
Class |
Lancelet
(Amphioxus) |
Chrodata |
Cephalachordata |
Tunicates |
Urochordata |
Ascidiacea |
Blue Shark |
Vertebrata |
Chonodrichtyes |
Blueback
Butterflyfish |
Euchordata |
Osteichthyes |
Northern leopard
frog |
Vertebrata |
Amphibia |
Pearl River
redbelly turtles |
Vertebrata |
Reptaillia |
Scissor-tailed
flycatcher |
Vertebrata |
Aves |
Grey fox |
Vertebrata |
Mammalia |
EXTERNAL
ANATOMY OF THE FROG
STRUCTURE |
PART
OF WHAT ORGAN SYSTEM |
FUNCTION/DESCRIPTION |
Nictitating
membrane |
Nervous system –
optic nerve |
A transparent part
of a frog’s lower eyelid that moves over the eye to clean it and
protect it. |
External Nares |
Respiratory |
The nares are
basically the nostrils of the frog. This is where |
Paired
Appendages (limbs) |
Skeleton |
Used for
locomotion. |
Eyes |
Nervous system –
optic nerve |
Used for vision |
INTERNAL ANATOMY OF THE FROG
STRUCTURE |
PART
OF WHAT ORGAN SYSTEM |
FUNCTION/DESCRIPTION |
MOUTH |
Digestive |
Entry way for food
and air |
Tongue |
Digestive |
Muscular structure
attached to the front of the mouth which is extended to catch insects
(its food). |
Eustachian tube |
Respiration |
Equalize air
pressure to the ears – mouth to ear tube. |
Maxillary teeth |
Digestion |
Sharp teeth in the
maxilla of a frogs mouth that function in holding captured prey. |
Vomerine teeth |
Digestion |
Small projections
in the top of a frog’s mouth that function in holding and captured
prey. |
Trachea (cannot
see) |
Respiratory |
Short tube from
glottis to lungs. |
Esophagus (cannot
see) |
Digestion |
Tube that connects
the mouth and the stomach in a frog. |
DISSECTION |
|
|
Coelom |
Digestion |
Body cavity |
Lungs |
Respiratory |
Exchange point
where CO2 leaves and O2 enters the blood |
Liver |
Endrocrine |
Secretes bile and
processes digested food molecules carries in the blood from the ileum. |
Gall bladder |
Endrocrine |
Sac which stores
bile. |
Heart |
Circulation |
Pumping organ of
the circulatory system (has 3 chambers). |
Atria |
Circulation |
Chambers that
receive blood. |
Ventricle |
Circulation |
Chamber of a frog’s
heart that pumps blood out of the heart to the lungs and other parts of
the body. |
Stomach |
Digestion |
Stores food and
mixes it with enzymes to begin digestion. |
Small Intestines |
Digestion |
The principal organ
of digestion and absorption of digested food. |
Large Intestines |
Digestion |
Posterior organ of
the digestive system which stores undigested food. |
Cloaca |
Reproductive –
urinary - digestiion |
Organ through which
the products of the frogs digestive and urogenital system pass when
discharged from the body |
Pancreas |
Endrocrine |
Gland which
secretes digestive enzymes into the duodenum. |
Spleen |
Endrocrine |
Organ in the frog’s
circulatory system that makes, stores, and destroys blood cells. |
Kidneys |
Urinary |
Filter and storage
for urine. |
Fat bodies |
Endrocrine |
Masses of fat in
the body cavities of frogs. Needed for hibernating and mating |
Testes |
Reproductive |
Male sex organs
that produce sex cells (sperm). |
Ovaries |
Reproductive |
Organs of the
female reproductive system that produce the eggs. |
Oviducts |
Reproductive |
Ovarie to cloaca
duct. |
Cloaca |
Reproductive –
urinary - digestiion |
Organ through which
the products of the frogs digestive and urogenital system pass when
discharged from the body |
Path of food through the
digestive tract of the frog.
Mouth, maxillary teeth, vomerine teeth, esophagus, stomach, small
intestine, large intestine, cloaca, anus
Which of these organisms is more closely related to man, a starfish or a
crayfish? Explain your answer.
Starfish/man. Both are
deuterostomes, a crayfish is a prototostome.
Why is the lancelet considered to be a
vertebrate?
They posses all four characteristics of a chordate. While heartless (a ventral aorta does the pumping), the overall pattern of the lancelet circulation is similar to that of the vertebrates. There are separate male and female lancelets, but fertilization is still external. Basic features of vertebrate nervous system organization are found in the lancelet, a primitive chordate related to vertebrates. The lancelet is vertebrate-like, but much simpler.