While a whale's fins are similar in structure and function to those of a fish, whales and fish are not closely related, so their similarities are defined as analogous, not homologous. The development of fins in two such ... More »

Pelvic fins can serve multiple purposes depending on the species of fish, like sharks use them for balance when swimming and on males they are part of the sexual organs, but fish like the O'opu in Hawaii use them to navi... More »

The dorsal fin provides stability while swimming. It may also regulate body temperature in warm-blooded animals such as the dolphin. The dorsal fin is located at the top of the animal. More »

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Homologous structures, such as the fins of whales and the hands of monkeys, demonstrate that while a species may use structures for different purposes, the species shared a common ancestor. By definition, homologous stru... More »

Male fish may have larger pectoral fins and small white spots on their heads and pectoral fins. Female fish may be larger and rounder than males. More »

Identify a fish based on the type of water it lives in, the geographic location, its body shape and color, the placement of its fins, and the absence or presence of scales. The placement of other body structures, such as... More »

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Some of the signs and symptoms used to diagnose disease in fish include inactivity, frayed fins, loss of color, erratic swimming and difficulty breathing, states FishNet. Other indications of disease can be open sores, b... More »