Mermaid.....'s purse

Hi Sea Fans!

I've been really busy setting up a new exhibit for the shark section and came across a lady who does something very interesting.  But let me give you a bit of background first...

Sharks keep our largest and most important ecosystem healthy…our oceans.  

Leopard catshark. Photo: (WT-shared) Pbsouthwood at old wikivoyage wts

Being at the top of the food chain in the marine environment, they help to keep fish stocks in the ocean healthy.  As our oceans cover over 70% of the earth’s surface and houses 80% of life on earth, maintaining (preserving and not destroying) this ecosystem is really really really important to life on earth! 

By monitoring (keeping an eye on) and understanding local shark species and what they need in order to do well, we can actually help to protect our natural heritage.  How, as average people who haven't studied science, can we help?  You just have to be willing to help... and you can be a citizen scientist!

Citizen science (CS) is scientific research done by non-professional scientists…Joe Blogs the lawyer, or Betty Boop the PA, for example.  Anyone can get involved in CS projects!

An example of a CS project that I came across was a shark egg case project run by Sheraine van Wyk on the Whale Coast in South Africa.  Regular shark egg case collections by volunteer groups along the Whale Coast shoreline,  provides information on the egg cases found at different beaches. This gives an idea of the shark species that occur offshore at those areas.

About 25% of all sharks reproduce (have babies) by means of an external egg.

These are the sharks that the Whale Coast Conservation project focusses on.

The eggs have different shapes, sizes and colours, but what makes shark eggs unusual-looking is that many have tendrils or hooks with which they attach to sea plants, rocks or other objects under water. 

Inside the egg the embryonic (baby) shark feeds off a yolk sac for up to nine months while it grows and develops.

Photo: Sander van der Wel

When ready, the mini shark hatches from the egg leaving the empty egg case behind.

The empty egg cases usually wash out of the sea and end up on the beach. If these ‘mermaids’ purses’ are found at a certain beach it indicates that the adult sharks or ‘parents’ are in the water nearby.  Scientists working on some of these types of sharks have already found that eggs are shed continuously throughout the year, except for one shark.   The St Joseph shark seems to do things a little differently because more of their eggs are found on the beaches at certain times of the year.  

St Joseph's shark. Photo: L. Barker from the Two Oceans Aquarium.

More research is needed to find out exactly what's going on.

Egg case collection will continue for a few years, so if you’re interested and in the area, contact Sheraine at Whale Coast Conservation (wcc@ocf.org.za) and lend a hand.

Have a great week Sea Fans!

Chat soon.

Cheers

Abby

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