Actinopterygii

File:Actinopterygii.jpg

Actinopterygii

File:Melanocetus johnsonii.jpg

Melanocetus johnsonii

Actinopterygii, also known as ray-finned fishes, are a class of bony fishes that constitute the largest class of vertebrates in existence today. They are characterized by the presence of lepidotrichia, or "fin rays," which are bony spines that support their fins. This group includes over 30,000 species, making it the most diverse class of vertebrates.

Anatomy

File:Anatomia dei pesci.jpg

Anatomy of a fish

The anatomy of actinopterygian fishes is highly varied, reflecting their diverse lifestyles and habitats. However, they share some common features:

• Skeleton: Actinopterygians have a bony skeleton, which is lighter and more flexible than the cartilaginous skeletons of cartilaginous fishes.
• Fins: Their fins are supported by bony or cartilaginous spines known as rays.
• Scales: Most have scales that cover their bodies, which can be ganoid, cycloid, or ctenoid.
• Swim bladder: Many have a swim bladder, an internal gas-filled organ that helps them maintain buoyancy.

Evolution

Actinopterygii have a long evolutionary history, with fossils dating back to the late Silurian period. They have undergone significant diversification, leading to the wide variety of forms seen today. The group is divided into two subclasses: Chondrostei and Neopterygii.

Diversity

Actinopterygii are found in a wide range of aquatic environments, from deep oceans to freshwater rivers and lakes. They exhibit a vast array of adaptations that allow them to thrive in different ecological niches.

Bluefin tuna

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Swordfish

Atlantic salmon

Atlantic cod

Ecology

Actinopterygii play crucial roles in aquatic ecosystems. They are primary consumers, predators, and prey, forming essential links in food webs. Many species are also important to humans for food, recreation, and economic purposes.

Related Pages

• Fish
• Vertebrate
• Osteichthyes
• Chondrichthyes

Gallery

• 
  Ancylopsetta dilecta
• Anableps anableps
  Anableps anableps
• Diaphus metopoclampus
  Diaphus metopoclampus
• Gonostoma elongatum
  Gonostoma elongatum
• 
  Anoplogaster cornuta