Bony Fish Anatomy PDF

**[CLASS OSTEICHTHYES]** (Emphasis) ***EXTERNAL ANATOMY OF BONY FISHES*** 1. **Body Shape:** \- Streamlined for efficient swimming, though some species have flattened or elongated shapes for specific habitats. 2. **Fins:** **Paired Fins:** - **Pectoral fins:** For steering and stabilizati...

**[CLASS OSTEICHTHYES]** (Emphasis) ***EXTERNAL ANATOMY OF BONY FISHES*** 1. **Body Shape:** \- Streamlined for efficient swimming, though some species have flattened or elongated shapes for specific habitats. 2. **Fins:** **Paired Fins:** - **Pectoral fins:** For steering and stabilization - **Pelvic fins:** Aid in maneuvering and balance. **Unpaired Fins:** - **Dorsal fin(s):** Provides stability. - **Anal fin:** Prevents rolling and aids in steering. - **Caudal fin:** Propels the fish forward (can be homocercal in most bony fishes, meaning the lobes are symmetrical). **3. Mouth:** \- Positioned terminally, superiorly, or inferiorly depending on feeding habits. **4.** **Operculum:** \- A bony plate covering and protecting the gills, aiding in respiration by creating water flow over the gill filaments. **5. Eyes:** \- Adapted for underwater vision, typically without eyelids. **6. Lateral Line System:** \- A sensory organ running along the sides of the fish, detecting vibrations and changes in water pressure. **7. Scales** \- Provide protection and reduce water resistance. **8. Skin** \- Contains mucous glands to reduce friction and protect against infections. ***SWIM BLADDER*** **DEFINITION:** A gas-filled sac located in the dorsal portion of the fish\'s body cavity. **FUNCTION** - **Buoyancy:** Regulates the fish\'s position in the water column without expending energy. - **Respiration:** In some species, it acts as an auxiliary respiratory organ. - **Sound Production/Reception:** Helps detect and produce sound in some fishes. **TYPES** - **Physostomous:** Connected to the gut via a pneumatic duct, allowing air to be gulped or released. - **Physoclistous:** No connection to the gut; gases are exchanged via the blood. ***TYPES OF SCALES IN BONY FISHES*** **1. Ctenoid Scales:** \- Found in advanced bony fishes like perches. \- Have tiny spines or teeth (ctenii) on their posterior edge. \- Provide flexibility and reduced drag. **2. Cycloid Scales:** \- Found in soft-rayed fishes like salmon. \- Smooth, circular, and overlapping with a uniform edge. \- Aid in streamlined movement. 3. **Ganoid Scales:** \- Found in primitive fishes like gars. \- Thick, diamond-shaped, and non-overlapping. \- Made of bone covered with enamel-like material for armor-like protection. **4. Placoid Scales (common in cartilaginous fishes):** \- Rarely present in some bony fish larvae.