Photo courtesy of Kate GardinePhoto courtesy of Kate GardineClose up of a Bighead:  Photo courtesy of Kate Gardiner



To some the Bighead carp might not be considered the best looking in the world, but there is no doubt that they have some unique adaptations to them.

David Riecks, University of Illinois/Illinois-Indiana Sea Grant

The first noticeable observation made when looking at these fish is the unique head structure; specifically the jaw region.  Bighead carp have a distinguishable lower jaw, that rises and protrudes outward.  Besides an upturned jaw, the eyes of a Bighead are much lower and more forward set when compared to the rest of the body.  The mouth of a Bighead carp is considered toothless and they lack barbels that are found on other fish.  Barbels are just the fleshy "whiskers" found on fish, which are receptors used for feeling and tasting around the environment.  There is a presence of pharyngeal teeth that are located on the gill arches used for grinding prey.  The common name gives clues to the body to head ratio, where their heads are often longer and larger in size, thus the name "Bighead".  Another adaptation of the head region is the lack of scales.

More then What Meets the Eye: As we continue on to the rest of the body you will notice distinguishable dark blotches all across the fish.  These blotches are especially found to be focused around the dorsal region of the fish.  For a better idea of where the dorsal region is and what these blotches look like view the elongated image above.  The typical color of the rest of the body is usually a grey color with a whiter underbelly.  Following along the top of the body you will find the dorsal fin.  This dorsal fin consists of the dorsal spine and rays.  The rays are flexible and segmented in the dorsal fin.  The main purpose of the dorsal fin for Bighead carp and many other fish is to provide stability.  This fin also aids in sharp movements through the water, as well as prevents the fish from rolling.  Besides the dorsal fin you can find the ventral and anal fins along the bottom of the fish.  The Bighead has a distinguishable keel as well.  The keel is the smooth abdominal edge starting from the ventral fin, extending beyond the pelvic base to the anal fin.Photo courtesy of Owen Johnson, USFWS  These fish also have a unique gill structure when compared to other organisms with gills such as the Smallmouth Bass, a common game fish of North America.  Click here to compare adaptations of the Smallmouth with the Bighead carp!  The gill rakes are very long, thin, and dense in numbers helping increase the flow of fresh water across the gills to increase in respiration.  Since the gills rakes are large it promotes gas exchange so Bighead carp can survive better in less oxygenated water.  The actual process of gas exchange is fairly simple in these organisms.  The circulatory system of Bighead carp is classified as an enclosed circulatory system.  As deoxygenated blood coming from the body is pumped into the atrium of the heart and then out the ventricle heading towards the gills where the blood can obtain oxygen.  Photo Courtesy M. Gaden, GLFCThanks to the gill structure it increases the surface area and blood can pump through the tiny capillaries housed in the gills where oxygen is exchanged through the tiny walls into the blood vessels thanks to the process of diffusion.  The blood then continues to the rest of the body where oxygen is needed for cellular respiration.  The blood diffuses oxygen across the low concentrations thanks to capillaries to different areas of the body.  Then blood will make the trip back to the heart to continue the process all over again.

School of jumping Silver carp - Photo courtesy of Asian Carp Regional Coordinating CommitteeOne of the most important adaptations to Bighead carp is the fact that these fish can grow to large sizes so quickly.  This adaptation allows Bighead carp to overrun many of the native fish as they eat the main food supply.  Their large size and quick growth allows them to compete with the native fish, forcing the native fish out of their environment.  This competition in the same niche causes a stress on many organisms, decreasing populations of the other organisms as the Bighead carp decimate the food supply and continue to grow and reproduce at fast rates.  Bighead carp can actually reach sizes of 100 pounds, but often average between 40-50 pounds.

Interested in how much Bighead carp can eat?  Click here to find  what makes a meal for them!


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