Download PRACTICAL LEC. 2 EXTERNAL APPEARANCE FOR FISH AND

PRACTICAL LEC. 2 EXTERNAL
APPEARANCE FOR FISH AND ANATOMY
Preface:Fish lives in the aqueous medium which is characterized by density and
viscosity higher than air, so the qualities of the body structure, physiology
and behavior in fish are closely linked with the nature of life in the water .
External Features :Fish are owns a formality shared attributes with each other to enable them to
live in the water , Includes; Sleek body without outcrops, body shape is
fusiform or oval in mostly and Covered with mucous material . Although very
different in terms of shape, the bodies of fish are symmetry side as in the case
of vertebrates.
Body divided in to : Head , Trunk , Tail
Head contain :Mouth : mouth shape depend on what the fish eat and how it eats
-superior mouth
most of carnivorous
-anterior mouth situation omnivorous
-inferior mouth situation herbivorous
Eyes: - The eyes are located on both sides of the head, and they are without
eyelids .
Nostril :- A pair of nostril is located on the upper side of the head in a bony
fish, its open in nasal hole that used as olfactory
member , but not
communicate with the oral cavity.
Operculum :- protect the gill arch.
Barbules: projection from skin have sensory function Some have & some
haven’t depend on type of feeding
‫ سامر سليم الشكرجي‬.‫م‬.‫ م‬-: ‫اعداد‬
PRACTICAL LEC. 2 EXTERNAL
APPEARANCE FOR FISH AND ANATOMY
Trunk: - contain : Fins :- Means of the movement and direction in the
fish.
paired : Ventral , Pectoral
- Unpaired : Dorsal , Tail , Anal
Fish scales : The skin in most fish species will be upping by presence of
strong scales which installed where. There are two types of scales, Cycloid
(like carp ) and Ctenoid (like perch ).
Function of scales:
Protection , determination of age, taxonomy, help in swimming.
The lateral line :A group of sensory organs only present in fish, his function news
the fish in any disorders get in the water and give signals about the state of
foreign objects.
Tail:-
‫ سامر سليم الشكرجي‬.‫م‬.‫ م‬-: ‫اعداد‬
PRACTICAL LEC. 2 EXTERNAL
APPEARANCE FOR FISH AND ANATOMY
Internal anatomy :Integumentary system (skin):The fish's body covers a thick skin to some extent in most of the
known species Different colors due to the presence of colorimetric cells .
Mucous material that you feel it when you catch the fish back to the presence
of mucous cells .
The skin consists of the following layers:Cuticle :- thin layer contain immuneglubins, lysozymes and free fatty
acids and these materials have very effective against pathogens
‫ سامر سليم الشكرجي‬.‫م‬.‫ م‬-: ‫اعداد‬
PRACTICAL LEC. 2 EXTERNAL
APPEARANCE FOR FISH AND ANATOMY
Epidermis:is a layer of squamous epithelial cells differs thickness
depending on the type, sex and location. Located in this layer mucous cells,
Club cells, lymphoid cells and macrophages .
Dermis: -consists of two layers
upper contain pigment
cells(chromatophores), mast cells, as well as scales. The Lower contain
colloidal consistent material give the skin a force.
Melanophores are the cells that contain dark pigment (Melanin).
Lipophores are the pigment cells containing different colors may be red are
called erythrophores Or may be yellow are called xanthophores.
Dermis layer also contains blood vessels and nerves, and this layer play a
major role in the formation of scales and other tissues related.
Hypodermis :- consisting of soft tissue that contains fat and dotted with blood
vessels.
The musculoskeletal system :Spine:- is consists of vertebrae that unfixed number in all kinds.
Ribs :- are found in the chest area.
‫ سامر سليم الشكرجي‬.‫م‬.‫ م‬-: ‫اعداد‬
PRACTICAL LEC. 2 EXTERNAL
APPEARANCE FOR FISH AND ANATOMY
Fish bones :- resemble rest of vertebrates from the synthetics, but not process
of blood formation , as happens in the rest of vertebrates.
Muscle: - There are three types of muscle :Smooth muscles , striated muscles and cardiac muscles .
Respiratory system: Gills :- is a place where the process of gas exchange occurs,its
located on both sides of the head, which is covered with operculum.
Gills consist of a row of thin filaments called primary lamellae which
consequences and form like a comb teeth, and expands the surface area of
these primary lamellae to be the secondary Lamellae which gaseous
exchange happens .
Secondary lamellae contain a large bloody network, and the blood is being
in direction of different to the path of the water, therefore, the process of
extraction oxygen it be high may reach 80%
Gills functions :1- Gas exchange
2- Organizing the exchange of salt and water
3 – Excretion nitrogenous waste
Circulatory system: The fish have (except pulmonary fish) single blood circulation from the body
to gills and then back again.
Heart: - located directly behind the gills in an area called pericardium .
Dorsal aorta: - is the main vessel for the transfer of blood from the gills to the
body, is located in the trunk directly under the spine .
Abdominal aorta: - transfer blood from the heart to the gills.
Caudal vein: - return blood from the tail to the heart.
‫ سامر سليم الشكرجي‬.‫م‬.‫ م‬-: ‫اعداد‬
PRACTICAL LEC. 2 EXTERNAL
APPEARANCE FOR FISH AND ANATOMY
Blood :The volume of blood in fish is relatively little ranging between 1.5 - 3% of
body weight compared to the volume of blood in the Vertebrates
Blood consists of liquid part called plasma and cellular part which includes
blood cells erythrocytes and leukocytes.
Erythrocytes :- characterized by Central location nucleated, oval form , 7-12
micrometer in length and her life stretches to four months.
Leukocytes :- consist of three main types are ; Lymphocytes ,Granulocytes
and Monocytes.
Granulocytes :- Includes three types of cells; Neutrophils , Eosinophils and
Basophils.
Haemopoietic tissues :The kidney, spleen and liver are hematopoietic tissues in Fish.
Excretory system :Kidney: - is located under the spine and divided into two zones frontal and
posterior , its Color ranges from light brown to oblique blackening .
Kidney function :1- Center for blood formation .
2- helps the balance of water and salts in the body.
3- Part of the reticulo-endothelial system .
4- hormones secretion .
5- Excretion of waste .
The digestive system :Esophagus: - Short muscular tube reach the mouth with stomach .
Stomach: - muscular organ which abound folds, differs in size depending on
the type of fish.
‫ سامر سليم الشكرجي‬.‫م‬.‫ م‬-: ‫اعداد‬
PRACTICAL LEC. 2 EXTERNAL
APPEARANCE FOR FISH AND ANATOMY
Liver: - large organ relatively with light brown or dark brown color
depending on the type of nutrition, is located in the front section of the
abdominal cavity.
Reproductive system :- There are three types of reproduction in fish are ;
Bisexual , Hermaphroditic and Parthenogenetic .
Testes :- a pair of organs hanging with mesentery membrane from upper wall
of the abdomen, its color backslash to white and smooth touch.
Ovary:- There is one pair of ovaries in advanced Fish and be stuck with each
other, hanging by mesentery membrane and located under the swim bladder,
its color yellow in adult fish and rough texture.
Swim bladder :- thin transparent tissue composed of two layers, does not
exist in a lot of fish that live in the deep water , produced gas by special
structure called oval organ .
Functions of swim bladder :1 - Basic function float and hydrostatic .
2- Secondary function of breath .
3- Receive and produce sounds .
Practical steps to examine the fresh fish:(1) A fresh fish won't smell fishy.
(2) Look at the scales They should be bright, and colorful. If the fish looks
dull it's old.
(3) Touch the fish. It should feel firm, not soft, and your fingertip shouldn't
leave an impression
(4) Look the fish in the eyes. They should be clear and dark . No white at all.
Fish with slightly cloudy eyes can be good, but must be approached with
care
(5) Check the gills. They should be bright red .
‫ سامر سليم الشكرجي‬.‫م‬.‫ م‬-: ‫اعداد‬