📘 Classification of Vertebrates Pisces

 

📘 Classification of Vertebrates

🔹 Vertebrates are divided into two main groups:

1. Group Pisces – Fish-like vertebrates without limbs
2. Group Tetrapoda – Vertebrates with four limbs (will cover soon, boss)

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🐟 Group Pisces (Fish Group)

• Pisces includes jawless, cartilaginous, and bony fishes. They do not have limbs, only paired and unpaired fins for swimming.

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🐍 1. Class Cyclostomata (Jawless Fish)

• Examples: Lamprey, Hagfish
• Jawless, eel-like, scaleless bodies
• Cartilaginous skeleton
• Single-circuit heart (1 atrium + 1 ventricle)
• External fertilization

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🦈 2. Class Chondrichthyes (Cartilaginous Fish)

• Examples: Shark, Skate, Ray, Ratfish
• Skeleton made of cartilage
• Body covered with placoid scales (denticles)
• Have jaws, paired pectoral/pelvic fins, and two dorsal fins
• Breathe using spiracles behind the eyes
• No swim bladder
• Internal fertilization
• Single-circuit circulation

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🐠 3. Class Osteichthyes (Bony Fish)

• Examples:
• Marine: Seahorse, Flying Fish, Angler Fish
• Freshwater: Rohu, Katla, Trout, Catfish
• Skeleton is bony
• Covered with dermal bony scales
• Swim bladder for buoyancy
• Gills covered by operculum
• Terminal mouth with jaws (teeth may or may not be present)
• Both paired & median fins
• Nervous system: 10 pairs of cranial nerves
• Mostly external fertilization

Related Posts

• Phylum Annelida
• Phylum Arthropoda
• Phylum Echinodermata
• Phylum Chordata