Tuesday, March 11, 2014

How Are Our Sea Stars Doing?

Many visitors to Pacific Science Center have been asking about a current ecological phenomenon known as Sea Star Wasting Syndrome. Have our Puget Sound Salt Water Tide Pool sea stars been affected?

The short answer is “No” and we are monitoring the situation closely. Pacific Science Center addresses the disease here including links to current research. Be assured that Animal Caretakers are recording any unusual appearances and movements of our sea stars in the hopes of having early detection if the disorder does appear. We are also taking photographs regularly and logging instances when staff report concerns about possible skin integrity.

The normal, relaxed posture of a sea star is open, like a star – with all limbs pointing straight out. The arms of sea stars contain sensory organs as well as the tube feet they use for movement. By spreading out their arms, they have access to the most sense data. But once in a while, the stars will take other postures.

Because crossed and twisted arms are an early indicator of the wasting disease, we are recording every time a star is noted in one of these positions. This will give us a good baseline for how often a healthy star is in one of these positions.

Sea star wasting syndrome is characterized by lesions of the skin – discolored, broken, or whitish areas where the epidermis has begun to break down. The white, calcium rich plates and spines of its skeleton become more obvious through its skin. But a sea star looks very different when it sits at or above the water’s surface than it does below. So far all our calls have been for stars that have parts of their body above the water level, and look funny but are actually fine.

We’ve also received few calls about the madreporite of our sea stars. This hard calcium ‘button’ on the top of every sea star is used to control the water pressure in and outside of the animal. Many people have never noticed the madreporite before, and wondered if it might be a sign of problems. We are fortunate to have many new eyes help us monitor our animals.

As more information is learned about this phenomenon, we will be reporting our findings. Until more is known, we will not be introducing any new sea stars or their relatives into the tide pool.

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