All posts by Coastal Detectives

I love the outdoors and all that it provides. I enjoy taking groups into outside spaces, and especially love being by the sea, on the coast and rock pooling.

Mermaid’s Purses

I love walking along the beach and especially along the strand line, to see what you can find. From natural treasures to plastic debris that’s been lost at sea, there’s always lots to pick up and discover. If you can safely visit a beach with young people at this time of year, there is always more to see after some strong winds, large waves or high tides.

Recently we have been picking up lots of Mermaid’s purses – these are egg cases from skates and rays that have developed and hatched in the Solent or out at sea. They are anything from 5 to 10cm in length and wash up on the beach, once the young skate or ray has hatched.

A video of a ray hatching can be found at https://www.youtube.com/watch?v=mx5RiXlLGco

There are about 12 species of skates, rays and sharks in the UK that we can identify by looking at their egg cases, and more specifically about 5-6 fairly common species on the South Coast.

To identify the Mermaids Purses, you will need to take your egg cases back to the classroom and put them in a bucket of fresh water for 24hrs, this will allow them to rehydrate, and return to their original size. You can then start to sort them by size and shape, and arrange them into groups.

The smallest egg cases, are about the size of a large bladderwrack (seaweed) popping case! They have thin curly tendrils coming from each corner.

There are a number of medium sized egg cases that are harder to identify, because they look quite similar. However, if you are keen, look closely at cases and use this ID key, provided by the Shark Trust, to identify them.

ID Key http://www.sharktrust.org/shared/great_eggcase_hunt/eggcase_id_key.pdf

Photo Key  eggcase_id_poster

Citizen Science – You can then help the Shark Trust by logging on to their Great Eggcase Hunt website and recording where you found your cases, and the number of each species found.

Project Website http://www.sharktrust.org/en/GEH_the_project