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What features distinguish ray-finned fishes from lobe-finned fishes?
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Vertebrate
The major groups of vertebrates include fishes, amphibians, reptiles, birds, and mammals.
Ray-finned fishes (Actinopterygii) and lobe-finned fishes (Sarcopterygii) are the two primary classes of bony fish. They are distinguished primarily by the structure of their fins and their evolutionary relationship to land vertebrates.
Fin Structure
- Ray-finned fishes: As the name implies, these fishes have fins supported by bony or horny rays. These fins are typically thin and lack the fleshy, muscular lobes found in their counterparts.12
- Lobe-finned fishes: These fishes possess fleshy, lobed fins. Structurally, these fins contain a pattern of bones that served as the evolutionary precursor to the limbs of tetrapods.3
Other Distinctions
- Respiration: While ray-finned fishes rely primarily on gills, some lobe-finned fishes, such as lungfishes, possess functional lungs that allow them to breathe air, an adaptation for living in shallow or seasonal waters.345
- Diversity: The Actinopterygii represent the largest and most diverse class of fishes, containing the vast majority of living species, including most commercial and sport fishes. In contrast, the Sarcopterygii are represented today by only a few living groups, such as the coelacanth and lungfishes.2634