Chomping Down on Crocodile Research

by Sandy Salle on March 27, 2012

Image above is owned and copyrighted by the Okavango Crocodile Research Group and was taken from their website, www.okavango-croc.com

Born in an effort to assist in developing effective crocodile population management strategies, the Okavango Crocodile Research Group dedicates its time to assisting the Department of Wildlife and National Parks in monitoring daily Nile crocodile activity.

In order to monitor these fascinating and aggressive creatures, the research group releases captive-raised crocodiles into the wild, using the Krokovango Sustainable Utilization Scheme. These animals are then closely monitored to evaluate pesticide contaminant levels and develop census surveys.

Below are highlights from several of the Okavango Crocodile Research Group’s detailed studies:

Can you see me?

One of the most fascinating studies that the research group is working on is crocodile eyesight under water—or lack thereof. The study found that crocodiles have a difficult time adjusting their eyes underwater and are actually far-sighted creatures.

Last year, the Okavango Crocodile Research Group collaborated on a study with Cornell University’s Professor Howard Howland, finding a new way to measure a crocodile’s focus beneath the water. Testing was performed using a photoretinoscope, which helped the group discover the extent to which crocodile can focus underwater and the distance in which they can focus on an object.

In order to use the photoretinoscope, the team had to send a light beam into the crocodile’s eye to see how the light was being reflected back into the camera. If the camera takes a picture of the croc’s eye with a red crescent at the top of the pupil, this would signify that the eye is focusing on a nearby object. If the red crescent is at the bottom of the pupil, this would signify that the croc was focusing on an object in the distance.

Image above is owned and copyrighted by the Okavango Crocodile Research Group and was taken from their website, www.okavango-croc.com

After running the same test on several crocs, the team found that each time, they came up with the same result. Crocs can’t focus on objects at close range, only ones in the distance.

So if crocodiles have difficulty focusing underwater than how is it possible for them to hunt beneath the surface and even in dark conditions? Thanks to keen senses and highly sensitive touch papillae on their cranial scales, crocodiles can rely on their other super senses to catch pray in difficult visual conditions.

See below for an exhilerating experience beneath the water . . .

 

Exploring an underwater city . . .

During another study performed in 2011, the research group analyzed the underground caves and channels found in the Okavango Delta by performing several specialized dives throughout these fascinating underwater routes.

These channels are believed to be formed primarily by hippos, pushing through the thick overlying vegetation, creating open channels for traveling underwater. Crocodiles can often be found lurking in these routes, most likely to avoid predators above and below the water’s surface.

Image above is owned and copyrighted by Graeme Duane and was taken from the Okavango Crocodile Research Group website, www.okavango-croc.com

Because these underwater caves are covered by thick papyrus vegetation, there are several areas in the papyrus that allow for conecentrated beams of light to pass through. Crocs use these openings to grab a deep breath of air before descending back down into the dark channels.

It is also possible that crocs seek the underwater Okavango caves during times when natural fires are common. These fires can often devastate large crocodile breeding sites on land, but it’s also possible that these fires affect conditions beneath the water. The investigation is still underway for the Okavango Crocodile Research Group.

For more information on the Okavango Crocodile Research Group and their studies, click here.

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