fish

Otolith bone

maintains balance

Homocercal tail

A symmetrical tail fin found in many fish like perch, where the top portion is the same as the bottom.

Heterocercal tail

A sickle-shaped tail fin that is not symmetrical, with the larger portion on the top, found in sharks and predatory fish.

Diphycercal tail

A tail fin that tapers to a central point, found in lungfish.

Eye

Receives visual images, response to stimulus

Nostril

Connects to the olfactory bulb in the brain and functions in chemoreception (odor detection).

Mouth

The beginning of the digestive tract, food intake.

Operculum

protects the gills and helps move water over them.

Pectoral fin

Maintains orientation and stability during locomotion.

Pelvic fin

Maintains orientation and stability during locomotion.

Anal fin

Maintains orientation and stability during locomotion.

Caudal fin

Provides thrust for locomotion.

Lateral line

Detects movement in the water via vibrations, also senses pressure, temperature, and salinity.

First and second dorsal fin

orientation and stability in locomotion

Gills

respiratory gas exchange.

Brain

motor coordination, sensory info integration

Spinal cord

connects impulses from brain to peripheral nerves

Kidney

Removes nitrogen waste and connects to the bladder.

Swim bladder

Regulates buoyancy by storing gases.

Gas gland of swim bladder

secretes gasses into swim bladder

oval body of swim bladder

reabsorbs gases from swim bladder

Ovary

egg storage and maturation

Bladder

stores waste until expulsion

Spleen

houses microphage cells

Duodenum

nutrient absorption, fat emulsification, toxin neutralization

Pancreas

Secretes digestive enzymes and hormones.

Cardiac portion of stomach

beginning of digestion

Pyloric ceca

increases surface area for nutrient absorption

pyloric portion of stomach

digestion

Liver

matbolizes fats, neutralizes toxins

Urogenital opening

Expels urine and eggs/sperm in females

Anus

Secretes waste from the digestive tract.

Blood flow sequence in fish

Atrium → Ventricle → Bulbus arteriosus → Ventral aorta → Afferent branchial arteries → Efferent branchial arteries → Dorsal aorta → Arteries → Capillaries → Veins → Hepatic portal (and other) veins → Sinus venosus → Atrium.