To be able identify and discuss fish, it is helpful to know all the types of fish fins. It makes descriptions much easier, and there really aren't that many. Here are the eight types of fish fins:. Of course, not all fish have every type of fin. Refer back to this page if you come across a fin you don't know while reading our fish identification series.
Home About Got a question? All articles. Generally, these variations involve special modification of the vertebral column. Following seven main types of caudal fins are found in fishes:. In some fishes, tapering and symmetrical types of fin is present which is known as isocercal or leptocercal caudal fin.
In this case, the spine is long with a straight rod-like structure. Rat tails Macruidae , Blennies Blennidae Eels Anguilliformes , feather backs Notopteridae , and Gymnarchids Gymnarchidae , etc have the isocercal caudal fin. This is a reduced type of caudal fin where some fin elements are fused together. They are found in cods Order: Gadiformes. In the modern lungfishes Dipnoi , the pseudocaudal caudal fins are found.
In this case, fins are developed from the backward growth of dorsal and ventral elements. This type of caudal fin bears much larger dorsal lobe than the ventral lobe which is greatly reduced. They are found in certain early Agnathans.
It is also known as inverted heterocercal caudal fin. In this case, the vertebral axis turns downwards sharply where the lobe develops from its upper surface.
It is a very specialized type of caudal fin which is also known as bridge caudal fin. Generally, they look like the isocercal fin but the fins are reduced to vestiges.
In this case, the caudal lobe is truncated where hypurals of the spinal column are lacking. These types of fins are found in the pearlfishes Carpus , Flerasfer and Orthagoriscus. Fish use their fins for various purposes. Some important functions of fins are described below:. Different types of median and paired fins are described below: Fish showing different types of fins. Different types of Caudal Fins.
Caudal fins shapes. A major difference is that with only one paddle a human paddler can still control the boat by alternating paddles, but with only one pectoral fin, a fish would have difficulty not spinning in circles -- thus the biological necessity for paired fins.
If you look at pectoral flippers of marine mammals under X-ray, you see an amazing likeness to the bones of the human arm and hands.
This is an example of homologous structures between different species and reinforces the fact that we share similar origins. Homologous structures are those which have the same origin but different, if sometimes only slightly different, functions. Comparisons between marine mammal dorsal fins and the dorsal fins of fish -- especially cartilaginous fish like sharks, which have no bones, are a bit different.
In that case, the structures are analogous, meaning they serve the same function, but evolved from different origins. This is a case where form clearly followed function, in which nature provided each animal a similar way to deal with the need for a keel. By using the site, you agree to the uses of cookies and other technology as outlined in our Policy, and to our Terms of Use. Location, Location Since fins and flippers are essentially the same thing, the difference between a dorsal fin and a flipper becomes a matter of location and function.
Keeping An Even Keel The dorsal fin is one of the so-called unpaired fins because it follows the midline down the body -- in this case, along the back. Paired Pectorals Whether you call them fins or flippers, those paired pectoral appendages serve to propel the animal through the water in the same way a human swimmer uses his arms.
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