There are three main groups of fish based on their skeletal structure. These groups are jawless fish, cartilaginous fish, and bony fish.
1. Jawless Fish: Jawless fish, also known as agnathans, include hagfish and lampreys. These ancient fish lack jaws and instead have a circular mouth with sharp teeth. They have a unique skeletal structure made of cartilage but lack true bones. Hagfish are predominantly scavengers, while lampreys are parasitic, feeding on blood and body fluids of other fish.
2. Cartilaginous Fish: Cartilaginous fish, as the name suggests, have skeletons made of cartilage instead of bones. This group includes sharks, rays, and skates. Cartilaginous fish have well-developed jaws with multiple rows of teeth that continuously grow and replace throughout their lifetime. They are streamlined and have tough, leathery skin. Many species are apex predators, playing a crucial role in marine ecosystems.
3. Bony Fish: Bony fish are the largest and most diverse group of fish, comprising over 95% of all fish species. They possess skeletons made of bone, which provide structural support. Bony fish have jaws with powerful teeth, gill covers, and often swim bladders for buoyancy control. This group includes familiar fish like tuna, salmon, goldfish, and angelfish. Bony fish display a wide range of adaptations and inhabit diverse habitats such as freshwater, oceans, and even brackish environments.
Each group of fish has unique characteristics that reflect their evolutionary history and ecological niche. Understanding these groups helps in comprehending the diversity and ecological significance of fish species.
Discuss the three groups of fish
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