fish anatomy and physilogy

Fish Anatomy

Anatomy/PhysiologyDefinition of terms:

• Anterior (cranial) toward the head• Posterior (caudal) toward the tail• Cranial head region• Caudal pertaining to the tail region• Dorsal toward the back (top) of the animal• Ventral toward the belly of the animal• Medial toward the median line• Distal away from the center or origin• Proximal toward the center or origin

Anatomy/physiologyAnatomy/physiology• External Anatomy of fish

– The body: divided into head, trunk, and tail. – The scales: primary protection, but still a place

pathogens could infiltrate.

• Even the head is covered by epidermis and some scales.


– Lateral line: is present along middle side of body.

– Head:• Nares: located on dorsal side of the anterior

end of head. – Each naris is divided into two portions

which permits water to circulate through the olfactory sac.


– Head:• Eyes: located in lateral position at anterior end

of head.

• Ears??

• Operculum: Located at the posterior and lateral positions of the head.

• Gill arch: Beneath the operculum are located four pair of gill arches.


– Head:• Gill arch:

– Each arch bears a gill on its outer surface.– Each gill consists of two rows of filaments.– Each filament consists of numerous

lamellae.– Inner margin of arch bears a single row of

tooth-like projections the gill rakers.

Anatomy/physiologyAnatomy/physiology• Sensory perception of the fish:

– Sight:• Sight is the predominant sense of salmon.

– Hearing:• Lateral line perceives sounds of low wave length.• Ear perceived sounds of higher wave length.

– Equilibrium:• Organs of equilibrium are the lateral line and the

ear.

Anatomy/physiologyAnatomy/physiology• Sensory perception of the fish:

– Touch:

– Smell:• Long range perception of chemicals• Preceptors of smell through olfactory sac

– Taste:• Taste is the perception of chemicals upon

contact.• Taste buds:

• Taste buds located on tongue and head.

Anatomy/physiologyAnatomy/physiology

• Sensory perception of the fish:

– Kinesthetic perception?

– Temperature:

• Function of lateral line


• Functions of various sense organs:– Eye:

• Sight– Ear: Inner ear

• Equilibrium and hearing– Nares:

• Smell– Lateral line:

• Hearing, equilibrium, touch, perception, and temperature

Anatomy/physiologyAnatomy/physiology• Internal Anatomy

– Skeletal system:• The function of the skeletal system is one of support.

– Skeletal tissues: •

– Axial skeleton:• Head, trunk, and tail regions.

– Head: – Trunk skeleton: modified portion of the

vertebral column.– Tail skeleton: remainder of the vertebral column

Anatomy/physiologyAnatomy/physiology• Supporting tissues:

– Connective tissue: ligaments, tendons, septa, fascia, and mesenteries.

• Ligaments: tough bands of tissue between bones.• Tendons: thick narrow bands by which muscles are

attached to the skeleton.• Septa: are heavy tissues which separate various

portions of the body.• Fascia: are the thin sheets of connective tissue

which surround muscles.• Mesenteries: are delicate tissues which support the

organs of the body cavity.

Anatomy/physiologyAnatomy/physiology• Muscular system:

– Three types of muscle tissue: smooth, striated, and cardiac.

– Smooth and cardiac: muscles are involuntary.– Striated muscle is voluntary.– Smooth or involuntary muscles:

• Found in various organs – –

– Cardiac muscle: is striated but involuntary.– Primary function of muscles is motion and locomotion.

Anatomy/physiologyAnatomy/physiology• Digestive system:

– Mouth, pharynx, esophagus, stomach, small intestine, pyloric cecae, liver and pancreas.

– Mouth: grasping organ; teeth function to retain prey.

– Pharynx: leads to the esophagus: – Esophagus: muscular tube leading from the

pharynx to the stomach.


• Digestive system:– Stomach: consists of two parts:

• Cardiac: • Pyloric:

–At end of pyloric section: heavy muscle»Pyloric sphincter:»

Anatomy/physiologyAnatomy/physiology• Digestive system:

– Intestine: duodenum, and small and large intestines.

– Duodenum: short portion of the intestine » pyloric caeca are attached and which

receives the bile duct and the pancreatic duct»

– Small intestine: predominant portion of intestinal tract.

– Large intestine: extremely short and located just anterior to the anus.

Anatomy/physiologyAnatomy/physiology• Digestive glands in the salmon and trout

include the gastric and intestinal glands, the liver, and the pancreas. – Gastric glands:– Intestinal glands: – Liver: a bilobed organ located in the anterior and

left lateral portion of the body cavity• Gall bladder: a thin-walled sac embedded in the

liver,

• Bile duct:

Anatomy/physiologyAnatomy/physiology• Pancreas: diffuse gland located on the

pyloric caeca

– Pancreatic duct: discharge enzymes into the intestine

• Pancreatic juices contain 3 enzymes that act on proteins, carbohydrates, and fats

Anatomy/physiologyAnatomy/physiology• Respiratory system:

– Gills: Function to exchange gases• Oxygen absorbed through gills into blood• • Gas exchange:

– Flow from dense to less dense

– Air bladder: doesn’t function as respiratory organ in salmonids

• • Fry and fingerling stages: air bladder connected

by duct to the esophagus (surface feeding?)

Anatomy/physiologyAnatomy/physiology• Circulatory system: Blood and lymph

systems– Blood: Fluid tissue – liquid plasma and cellular

components• Plasma: 80% water

– Proteins and carbohydrates– Waste materials (urea and uric acid)– Mineral salts– Enzyme secretions from glands– Antibodies

Anatomy/physiologyAnatomy/physiology• Blood cells

– Red cells (erythrocytes)• Flattened, nucleated cells with hemoglobin

– White cells (leukocytes)•

– Thrombocytes: Present in blood and aid in formation of blood clots

• Blood vessels: Closed system which blood circulates – heart, arteries, veins, and capillaries– Heart: Consists of 2 chambers - auricle(atrium) and

ventricle

Anatomy/physiologyAnatomy/physiology• Lymph system: consists of plasma and

leukocytes – Starts in the intercellular spaces and eventually empty

into veins– – Spleen is associated with lymphatic system– GALT and MALT

• Blood producing organs:–

• Functions is same as bone marrow in mammals

– Spleen, lymph nodes, and thymus:

Anatomy/physiologyAnatomy/physiology• Primary functions of major organs:• Pancreas:

• Spleen: produces leukocytes, serves as a storage space for RBCs, and destroys worn out red blood cells

• Kidney: divided into 2 parts– Anterior: produces red and white blood cells – Posterior:

• Swim bladder: hydrostatic organ

Anatomy/physiologyAnatomy/physiology• Heart: serves to move blood through circulatory

system – consists of atrium, ventricle, and bulbous arteriosis (smoothes out pressure to steady flow)

• Liver:– Detoxification, digestion, excretion, and

hematopoiesis• Digestion: secretion of bile salts• Excretion: destruction of worn out RBCs,

conversion of hemoglobin into bile salts and ammonium salts into urea

• The liver also serves for storage of glycogen (animal starch)

Anatomy/physiologyAnatomy/physiology• Gastro-intestinal tract:

– Cardiac and pyloric stomach:•

– Pyloric caeca:

– Small intestine: digestion and absorption of food• Enzymes secreted by glands – break down proteins

and carbohydrates• Carbs. and proteins absorbed directly in to bloodstream

– Large intestine: serves as storage space for accumulation of waste before excretion

fish anatomy and physilogy

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