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Prey Preference Study

Posted by: | August 3, 2009 | 4 Comments |

September 1, 2009

Finally my fish are hunting again. I think part of my problem was that the lights in the lab were constantly on.  This could have stressed out my fish and might explain their apparent grogginess during the feeding trials.

August 29, 2009

Still having some issues with this experiment. The last two trials were unsuccessful.  One fish gained a bulgy eye overnight, so I will be cleaning the tank and starting over with that one.  The second fish showed no interest in the feeder fish.

August 23, 2009

Unlike my behavioral study, my prey preference study has run into a brick wall.   When my fish aren’t cooperating tanks are overflowing, dividers are failing to keep fish separate, and time is constantly ticking. I have not yet given up on the experiment as I have high hopes for Jaba the Hut, Yoda, Princess Leia, and Han Solo. The fish seem to be fully acclimated to the tanks and trials will start soon.

 August 10, 2009

For the past five days I have been attempting to run my first prey preference trials with my two new fish: R2D2 and Luke Skywalker.  I say “attempted” because thus far I have observed R2D2 stare mindlessly into the corner for his entire 30 minute trial while Luke Skywalker swims up and down the tank, enthralled by his own reflection on the glass.  I’m allowing more time for my fish to acclimate, but I may have to be flexible and go back to the drawing board. 

August 5, 2009

Finished the rest of my feeding trials with Obi Wan today.  He was exposed to the last two pairs:  Bridled Gobies and Blueheads, then Blueheads and Damselfishes.    In the first pair, Blueheads were the only fish eaten during the thirty minute period.  The second trial resulted again in the consumption of Blueheads.

These trials that I have been doing with Obi-Wan are more test runs before the real thing.  This is because Obi-Wan has become so accustomed to eating mosiquito fish in a tank.  Tomorrow I will be catching all new feeder fish and two more lionfish.  The idea is that the more trials that I can run this summer, the more accurate and hopefully conclusive my data will be.  I will keep you all updated on any interesting observations and hopefully get some new pictures posted soon.

August 4, 2009

I ran my first trial this afternoon!  Last night I left my feeder fish and lionfish in the aquarium so they could acclimate to their new habitat.  On one side of the divider I had three Damselfishes and three Bridled Gobies while on the other I had a very hungry lionfish.  ( I decided to run my trials with only two different species of feeder fish because it will make analyzing my data easier.  This means that each lionfish I use will go through three trials: A- Damselfishes and Bridled Gobies, B- Damselfishes and Blueheads, and C- Blueheads and Bridled Gobies).  The trial procedure is very simple: I remove the divider, start my stopwatch, and take notes on everything the lionfish does for 30 minutes. 

My first trial resulted in the consumption of two Bridled Gobies; leaving one goby and all three Damselfishes to live another day.  When I first removed the divider, the lionfish (named Obi-Wan because his owner, an 8 yr old boy named Nash, is currently obsessed with Star Wars)  immediately started stalking the Damselfish. This is likely because lionfish are very visual hunters and Damselfish are very quick and flashy fish.  The Damselfish were very good at avoiding Obi-Wan ,however, by staying close to the rock and quickly retreating when he approached. 

 It took a bit longer for Obi-Wan to notice that the Bridled Gobies were even there, but when he did the hunt was on.  Because gobies rely on their camouflage, Obi-Wan was able to get very close to them before striking.  In addition to this obvious advantage I watched Obi-Wan demonstrate a very cool behavior that I’ve heard of from other researchers here, but never witnessed.  As the lionfish approached, he used his mouth to puff jets of water at the goby, likely trying to simulate a current. Nearly every time the goby would turn straight toward the stream of water the lionfish was producing and right at that moment Obi-Wan would strike.

I watched this pattern of behaviors continue with each goby throughout most of the trial.  During this time it seemed Obi-Wan had completely forgotten the Damselfish were there, as he was extremely intent on catching the gobies.  Near the end of the trial one of the gobies escaped death when it was startled under a rock by Obi-Wan’s jets of water.  For the remaining time Obi-Wan went back to stalking Damselfish but was unsuccessful.

August 3, 2009

I just finished getting an aquarium set up that is half rocky substrate and half sandy bottom with the goal of making the tank as close to realist as possible.   The day before I captured three different fish species for the feeding trials: Damselfish, Blueheads, and Bridled Gobies.  I chose these fish because each represents a larger group of fish. Damselfish represent fish that are generally tied to the substrate. They swim around in the water column, but tend to stay near a rock or shell they can hide in.  Bridled Gobies represent the bottom dwelling fish.  They are usually found in the open sand near rubble or substrate that they can swim to when approached.  Generally they stay very still in the sand, relying on their camouflage to protect themselves from predators.  Lastly, Blueheads represent fish that swim freely in the water column.  They aren’t generally attached to any one coral head and they swim higher in the water column than Damselfishes.   The plan is to expose these three species of fish to a lionfish and allow the lionfish to hunt for 30 minutes.  Any attempts to feed and successful feedings will be recorded along with how long it took the lionfish to do so.

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  1. By: Tammy Doty on August 3, 2009 at 7:50 pm      

    Hey Emily—

    I have thoroughly enjoyed reading your blog–I check for updates daily. It is so exciting to see that you are doing something you have always wanted to do. I am impressed with your work and can’t wait to read more about it. It gets me thinking about the lionfish (which is kind of cute by the way) and how, not having predators, it could really take over. Maybe once it eats everything there, it will have to move on, unless it likes the coral too. Can’t wait to learn more and see where this adventure take you and the lionfish.
    Great job! I’m proud of you.
    Tammy Doty

  2. By: Ketih Schilling on August 7, 2009 at 1:24 pm      

    Keep up the blog and take some pics! Enjoy you time in the Bahamas before school starts calling!

  3. By: Jay Mathisen on August 11, 2009 at 12:30 pm      


    Congrats on this outstanding opportunity and the experiences you are living. I enjoyed catching up on your blog this morning. I will pass this info along to staff here at LPHS. Take care, and enjoy your work and the remaining days in the Bahamas.

  4. By: Tammy Doty on August 12, 2009 at 10:55 pm      

    Maybe R2D2 needs to find the force? Ha-ha!

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