15 November 2010

Shyshark shenanigans

Xavier Zylstra
Juvenile shysharks at the Discovery Centre

Xavier Zylstra is a senior teacher at the Environmental Education Centre. He joined the Aquarium in April 2009 after 21 years as a high school biology teacher. He presents lessons about various environmental topics and special animals kept in the Discovery Centres to visiting groups of all ages, along with the other members of our dynamic team.

Last July a batch of shyshark eggs were brought up to me in the Upper Discovery Centre for dissection, as they appeared to be dead. However, careful inspection of the eggs, by shining a light through them, revealed large yolks with tiny wriggling embryos – the eggs were still very much alive!

As you may know, shysharks lay their eggs in clusters of seaweed. Long coiled tendrils, which extend from the corners of the rectangular egg cases (giving them the name “mermaid’s purses”), get caught in the seaweed and hold the eggs in place for the seven months or more that they need before they can hatch.

We installed the egg cases in one of the Upper Discovery Centre tanks and inspected them regularly. Imagine the excitement, four months later, when tiny 4cm-long shysharks started to emerge from the cases. Eventually, there were nine thriving shysharks, ready to star in shark lessons attended by school children from the Cape Peninsula.

In their short lives thus far, these amazing little ambassadors have done a great deal to change the perspective of hundreds of school children, who started off in the lessons labelling sharks as bloodthirsty maneaters and left thinking of them as cute, cuddly and endangered …

A shyshark egg case or "mermaid's purse"

It was a matter of great concern, a few weeks ago, when one of the shyshark youngsters appeared to have developed a bubble in her gut, leaving her a little bloated and incapable of diving and staying at the bottom. It felt awful arriving in the mornings to see her floating at the top of the tank, fast asleep.

It was suggested that she should be “burped”, but repeated attempts by aquarists were to no avail. Aquarist Maresia Haasbroek suggested that the shyshark be put in a deeper tank, as the greater depths and pressures might help compress the bubble.

As this was not practically possible in any of the aquarium displays, it was decided that it would be best to release the shark. On his next collection visit to Granger Bay, aquarist Nick Cremonte came to collect the bloated baby and took her with him in a jar of water.

He took her down to a depth of about ten metres and carefully opened the bottle, gently removing her and burping her again. This time small bubbles came streaming from her mouth and, on being let go, the plucky little shy shark headed down toward the nearest clump of kelp and disappeared into a convenient hiding space.

We wish her luck and a long life in her new home. It is heartening to know that our entire curatorial team will go to such lengths to ensure the good health and wellbeing of our animals. Thank you Nick!

Read more about the dark and puffadder shysharks in our Oceans of Contrast: Atlantic Ocean Gallery.

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