Answer: Characteristics: The fins are supported by rays, as the name indicates. In contrast to the cartilaginous fish they have a rigid skeleton. The swim bladder is also a unique feature of most ray-finned fish, enabling them to maintain buoyancy as they move up or down in the water.
Actinopterygii are bony fish that have spiny fins.
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A pair of nephridia is present on each segment of the earthworm, They are similar to flame cells in that they have tubules with cilia and function like a kidney to remove wastes.
