Thursday, December 29, 2011

A Date with Medusa

Our morning today was a little different from most mornings at the office.  Kathlina and I decided to walk over to Ocean Journey, the marine-focused building at the Tennessee Aquarium.  We were going to help our aquarist friends feed Medusa, the Giant Pacific Octopus (Enteroctopus dofleini)
Medusa the Pacific Giant Octopus in the corner of her tank.
When we first arrived at her enclosure, she was curled up in the corner of the tank furthest from us, and was not being particularly social.  We decided to let her stay in her corner and threw a pan of shrimp toward her, which she quickly began to explore with on of her eight tentacles.
Medusa putting a tentacle into the pan of shrimp.
Once she was finished with her shrimp and playing with the pan, we served her the next course of breakfast.  Octopi are very intelligent, so staff at the Aquarium provide enrichment activities for Medusa to prevent her from getting bored.  One enrichment activity is making her work for her food.  Shrimp and squid are placed into a closed container that has a screw top, and the whole container thrown into the tank. It was entertaining to watch her try to open the container. 
Medusa curled up around the container full of shrimp and squid.

As she worked on getting to her breakfast, she slowly moved closer to Kathlina and me, providing a great photo opportunity that highlights some of the interesting traits octopi possess.

An underwater view.
Cephalopods are the class of invertebrates that include the octopus, squid, cuttlefish, and nautilus.  This is a very unique group of mollusks (yes, they are related to clams and oysters!).  Probably the most noticeable feature of cephalopods is their tentacles. They are lined with suction cups and assist with locomotion, eating, and anchoring the animal down.  To see a video of these amazing appendages in action, check out TNACI's Facebook page.

Close-up of Medusa's tentacle.
Some of the more remarkable traits about cephalopods is their developed senses, large brains and their ability to change color.  While other mollusks do not have eyes, cephalopod eyesight is very keen and is the main sense they use to hunt.  The intelligence of octopi is highly debated, but they do possess a brain larger than other invertebrates and experiments have shown an ability to solve mazes.

The group of cephalopods that includes squid, octopus, and cuttlefish (subclass Coleoidea) possess pigmented cells called chromatophores. Contracting and relaxing small mussels around the chromatophores causes the animal to change color, and they can do so very quickly.  Color change occurs during reproductive activities, times of stress, or in an attempts to camouflage with the surrounding environment.  Octopi can also change the texture of their skin.  We were lucky enough to catch Medusa in the middle of a color change.

Chromatophores allow octopi to change color.
Eventually, Medusa did get to the squid in the container we threw to her.  All-in-all it was a fun morning and a nice change in routine. 

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