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Internal features of goldfish
In the
body cavity, there are kidney, swim bladder, gonad and digestive
organs in succession from dorsum to abdomen. Goldfish's heart
is found in pericardial cavity.
| A、Musculoskeletal System |
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Goldfish can swim with the
help of musculoskeletal system. Its skeleton can be classified
into two types: principal skeleton and appendage. Controlled
by nerve system, muscle attached to skeleton makes contraction
so that goldfish can swim. |
| B、Digestive System |
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Foods are transformed
into nutrition of fish body through digestion and absorption.
The indigestive food is released in the form of faeces.
Goldfish is always seen with a long line of faeces because
its sphincter on anus is undeveloped. Goldfish's digestive
system consists of mouth, pharynx and larynx, pharyngeal
teeth, intestine, gallbladder, liver, pancreas and anus.
It cannot swallow big-sized meat owning to its following
features that its mouth is small; jaw has no teeth; mouth
protrudes forward and internal wall is smooth. The thick
muscles on upper lip, which can flex freely, help some
food in mouth go further and release some out of mouth;
so take-in-and-send-out movements come up while goldfish's
eating. Behind mouth is pharynx and larynx, under which
exists a pharyngeal tooth that will grind the food. After
going through the abovementioned organs, food comes to
esophagus and intestinal duct. Intestine is divided into
three parts: foregut mid-gut and hindgut. There is no
stomach in body cavity. Goldfish's overfeeding will make
foregut expanded; its front abdomen looks swollen, which
is harmful to goldfish's health. It is suggested that
goldfish not get too much at a time. Please feed goldfish
in the way of less amount and frequent meal.
hepatopancreas: Made up of pancreas diffusing around
liver, hepatopancreas is a double-leaf filemot organ in
the upper front part of mid-intestine. It can produce
digestive mucus and detoxicate poisonous in body.
gall bladder: Most surrounded by liver, Gall bladder
appears oval. Digestive mucus made by liver and spleen
is stored in gall bladder. |
| C、Respiratory System |
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Respiratory system helps goldfish
inspire oxygen and expire dioxide. In the system the main
important organ is gill.
Gill:it is in the gill cavity under opercula. In
each cavity are four pieces of gill arch on which are
two gill lamellae. Gill filaments with abundant capillaries
are lined on gill lamellae. When the mouth and opercula
move harmoniously, bringing the dissolved oxygen into
capillaries, water flows through gill, meanwhile dioxide
in blood is released to water. |
| D、Excretion System |
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The metabolic waste is released
through excretory organs of kidney, urinary bladder and
gill.
Kidney: there are two dark-red long steaks lying
under the backbone and closely attaching to the backside
of body cavity. This is the kidney, which produces urine
and excretes waste.
Urinary bladder:it is a flat and oval bladder and
opens outwards between anus and vent. At the back of urinary
bladder is urethra. The bladder is undeveloped.
gill: most metabolic waste is released through
gill. |
| E、Circular System |
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Goldfish's life activities
are embodied through the cells with different functions.
The absorbed nutrition and oxygen as well as the released
waste and dioxide are carried by circular system.
heart: it is made up of one atrium and one ventricle.
Situating near the connection of head and body, heart,
the power of the circular system, is in pericardial cavity.
Blood makes a circulation powered by movements of heart.
Blood vessels: there are three types of blood vessels:
arteries, veins and capillaries. Among them, capillaries
are very small, however there are many capillaries spreading
throughout the whole body and providing room to exchange
gas and substance.
blood: blood of goldfish is red. |
| F、Urogenital System |
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Goldfish's reproduction is
finished by urogenital system. Goldfish are oviparous.
They are divided into two kinds: male and female.
Spermary: the main gonad of male goldfish is a
pair of spermaries that situate below the swim bladder
and the back of hepatopancreas. Spermaries are long and
flat. They can produce sperms after maturity.
ovary: the main gonad of female goldfish is a pair
of ovaries. Mature ovary is full of yellowish eggs. Zygotes
form new fries after external fertilization of sperms
and ova. |
| G、Balance System |
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Swim bladder: filled with gas, it looks like
a long bad. Swim bladder is often divided into front
and back parts with a compressed middle. The main function
of swim bladder is to make goldfish up or down while
adjusting their specific gravities by gulping or expelling
air.
Neural system and endocrine system: Neural system
and endocrine system have the function of coordinating
movements of all kinds of organs to make all the organs
an integer.
Neural system: it consists of brain, spinal cord
and nerves. The ends of nerves are connected with all
kinds of sensory organs (sensory organs in the skin，acoustical
organs、olfactory organs, optical organs etc), and muscles
to get impulses. Brain nerves and spinal cord can control
activities of the whole body.
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| H、Endocrine System |
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controlled by neural system,
endocrine system adjusts all kinds of life activities
of goldfish by excreting hormone. |
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