• Examples: Sharks, rays, skates, and chimaeras.

• Features:

• No swim bladder.

• Tough, sandpaper-like skin covered with tiny tooth-like scales (placoid scales).

• Mostly marine species.

A. Ray-Finned Fish (Subclass: Actinopterygii)

• Examples: Salmon, trout, goldfish, tuna, seahorses, and eels.

• Features:

• Fins are supported by long, flexible rays or spines.

• The majority of modern fish fall into this category.

• Found in both freshwater and marine environments.

• Features:

• Fins are fleshy and lobed, supported by a central bony structure.

• Considered close relatives of tetrapods (four-legged land animals).

• Examples: Hagfish and lampreys.

• Features:

• Eel-like bodies with no scales.

• Simple skeletons made of cartilage.

• Scavengers or parasites in marine and freshwater environments.

• Freshwater Fish: Live in rivers, lakes, and streams (e.g., catfish, bass, and tilapia).

• Marine Fish: Inhabit oceans and seas (e.g., clownfish, mackerel, and groupers).

• Diadromous Fish: Migrate between freshwater and saltwater during their lifecycle.

• Anadromous: Spawn in freshwater, live in the sea (e.g., salmon).

• Catadromous: Spawn in the sea, live in freshwater (e.g., eels).

• Herbivorous Fish: Feed primarily on plants and algae (e.g., parrotfish, tangs).

• Carnivorous Fish: Predatory fish that feed on other animals (e.g., barracuda, lionfish).

• Omnivorous Fish: Consume both plant and animal matter (e.g., tilapia, goldfish).

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