Fish Anatomy and Physiology (PDF)

‫بسم الله الرحمن الرحيم‬ Fish anatomy and physiology By Dr. Awatef Hamed Hamouda Associate Professor of Fish Diseases 1 Fish Are cold-blooded, poikilothermic animals (its temperature change acc. To environmental temp.) differ from warm- blooded animals in:...

‫بسم الله الرحمن الرحيم‬ Fish anatomy and physiology By Dr. Awatef Hamed Hamouda Associate Professor of Fish Diseases 1 Fish Are cold-blooded, poikilothermic animals (its temperature change acc. To environmental temp.) differ from warm- blooded animals in: 1.Absence of thermo-regulating center. 2.Modified respiratory organ (gills) and modified locomotors organs (fins), gas bladder,…….. 3.Absence of a well-developed immune system as animals. 2  Structural anatomy of fish Fish classified according to their skeleton in to : Bony fish (tilapia) or cartilaginous fish (sharks). Bony fish are classified according to feeding habits: Examples Description Feeding Type Feeds on other animals, including smaller fish, Sea bass Carnivorous crustaceans, and invertebrates. Feeds on plant material, including algae and Grass carp Herbivorous aquatic vegetation. Eats both plant and animal matter, allowing them Cichlids to adapt to various food sources depending on Omnivorous availability. Filters small particles from water, including Herring Filter Feeders plankton and detritus. Scavengers Catfish Consumes dead or decaying matter 3 (Piscivorous) According to migration pattern  Non-migratory or migratory.  Migratory fish: Examples Description Migration Type Salmon Ocean to freshwater Anadromous Eels Freshwater to ocean Catadromous Migration within Tuna, Herring Oceanodromous oceanic waters Migration within Trout, Bass Potamodromous freshwater Movements based on Striped Bass environmental Seasonal Migrants factors 4 According to salt range tolerance 1. Freshwater fish: typically thrive in salinities less than 0.5 ppt (parts per thousand) as Clarias gariepinus. gariepinus 2. Brackish water fish: Adapted to live in environments with salinities between 0.5 and 30 ppt, such as estuaries as grey mullet. 3. Marine water fish: generally inhabit waters with salinities greater than 30 ppt as Sea bass 5 According to temperature range tolerance 1. Cold water fish: live, feed, grow and reproduce in temperature less than 10-15o C. 2. Temperate water fish : 15-35o C. 3. Warm water fish : more than 35o C. 6 According to type of breeding Examples Description Breeding Method Lays eggs; external or Cichlids Oviparous internal fertilization Guppies, Mollies Gives birth to live young Viviparous 7 Fish body an be divided into: Head, trunk and tail. 8 9 Body forms of fish: 1. Oval or fusiform. 2. Depressiform. 3. Long and skinny or filiform. 4. Compressiform. 5. Taeniform. 6. Globiform. 10 Oval or fusiform: Black fin tuna 11 Tuna 12 Flat or depressiform: e.g. Oban Skates 13 Long and Skinny or Filiform 14 Compressiform: Angelfish 15 Taeniform: "Ribbon-like." Example shown is a gunnel 16 Globiform: Tetradon lineatus 17 18 skin 1. 1st line of defense against M.O. (intact skin, mucus secreted ). Mucus contain Ig, proteolytic enzymes. 2. Mucus carry away the M.O.(micro-organisms) and harmful chemicals. 3. Mucus minimize the energy loss (prevent the friction). 4. Has a respiratory, excretory and osmo-regulatory functions. 5. Coloration and Camouflage 6. Sensory Reception: Contains nerve endings that detect touch, temperature, and pain. 19 Fish according to scales :  Scale less fish (leathery): as catfish and eels.  Scaly fish: Scales generally serve to protect the fish’s skin used for fish identifications and aging. 20 Types of scales: Examples Shape Description Scale Type Tooth-like, found in Sharks Placoid cartilaginous fish Rhomboid- shaped, tough Sturgeons Ganoid armor‫معين‬ ‫بدرع‬ Salmon, Smooth, Cycloid Carp circular Perch, Spiny or Ctenoid Sunfish 21 comb-like  Skin appendages: fins  Paired fins: As pectoral fins, pelvic fins (ventral fin).  Unpaired fins: As dorsal fin, anal fin and caudal fin. 22 External anatomy of fish: 23 External anatomy of fish: 24 Fin's function:  Pectoral Fin: Allows for abrupt changes in side-to-side direction and speed. Acts as a brake‫ فرامل‬to decrease speed while swimming.  Pelvic Fin: Stabilizes the fish while swimming and allows for up-and-down movement in the water.  Anal Fin: Stabilizes the fish while swimming.  Caudal Fin: Moves, propels or pushes the fish through the water.  Dorsal Fin: Helps maintain balance while swimming.  Adipose Fin: it is not present on a lot of fish species. Its purpose is unknown. Salmon and catfish have an adipose fin. It is the small, thick, fleshy fin located between the dorsal and caudal fins. 25 Spines and Rays: bony structures supported the fins.  Scientists use fins to help identify and classify fish species. In more evolutionarily advanced fish, the fins are supported by bony structures: spines and soft rays. Spines are simple, unbranched, structures. Soft rays are compound, segmented, and branched structures. 26 27 Dorsal fin drawing of a soldier fish’s second dorsal fin, showing fin spines (unbranched) and rays (branched and softer than spines). 28 The elongated dorsal fin of a common carp, with 1 spine and 15-22 soft rays: 29 30 Eyes, nares and operculum:  Eyes: Used for sight, fish can detect colors and see short distance with their eyes. They use their vision to escape predators and find food.  Nares: Similar to nostrils, except nares are used for smelling only (nostrils are used for both smelling and breathing).  Operculum: The operculum is the bony flap that protects the gills from harm. It opens and closes to allow water to pass over the gills. 31 Mouth: The mouth is used to consume food. 32 33  Feeding Examples Behavior Positioning Mouth Type Mid-water Cichlids feeder; Front of head Terminal omnivorous Anglerfish Surface feeder Upward-facing Superior Catfish Bottom feeder Underside Inferior Snatching Hogfish prey‫خطف‬ Extendable Protrusible Probing Needlefish crevices; surface Long snout Elongated feeding Crushing hard Hard hinged Parrotfish shells structure Beak ‫منقار‬ 34 Barbels: They are the "whiskers" found on the head area of fish such as catfish or bullheads. On the catfish and bullheads, barbels are thought to be a sensory organ to help track down prey or food. Sturgeon also have barbels. 35 Lateral line  A row of small pits that contain special sensory hair cells. These hair cells move in response to motion near the fish. The lateral line sense is useful in hunting prey, escaping predators, and schooling. 36  Fish Senses 1. Eyesight: Fish can see in two directions (one eye focusing on an object independent of the other whereas human’s eyes can only focus on one object at a time). 2. Hearing: Fish have ears but not external ear openings like humans do. Their ears lack a middle and outer ear because sound travels faster in water than in air. Fish have internal ears with pairs of inner ear bones called otoliths. The otoliths allow fish to sense sounds in the water. Fisheries biologists can also use these bones (otoliths) to age fish and determine the health of fish populations. 37 Fish Senses 3. Smell: Fish use their sense of smell to locate food and to aid in migrating. 4. Taste: Some fish have taste buds, however, these taste buds are located on the outside of the fish’s head and fins in small pores. Some fish like catfish have a very developed sense of taste. 5. Touch: skin and lateral line. 38 Ears:  Fishes have two inner ears embedded in spaces in their skulls. The lower chambers, the sacculus and the lagena, detect sound vibrations. Each ear chamber contains an otolith and is lined with sensory hairs. Otoliths are small, stone-like bones. They float in the fluid that fills the ear chambers. Otoliths lightly touch the sensory hair cells, which are sensitive to sound and movement. 39 A pair of otoliths from a 160lb eight-banded grouper: 40 Fish ear: 41  Spine and spinal cord:  Spine:  Spinal cord: Connects the The primary structural framework upon which the fish's body is built; brain to the rest of the body connects to the skull at the front of and relays sensory the fish and to the tail at the rear. information from the body to The spine is made up of numerous vertebrae, which are the brain, as well as hollow and house and protect the instructions from the brain to delicate spinal cord. the rest of the body. 42 Skeleton of a fish 43