I didn’t mug a mermaid. It was already empty when I found it discarded amongst a tangle of seaweed on the river beach looking more like a fishing float than anything of value. Algal blotches spotted its sides like a paving slab in need of a power hose and a couple of strands of sea lettuce hung limply off its broken purse strings. But I still picked it up. After all, any purse, lost, stolen, wilfully abandoned, might still be identifiable. Even a mermaid’s purse.
It’s a bit of a misnomer really. It never did belong to a mermaid. It’s not even a purse. I did report it to the proper authorities but I don’t think they’ll be too worried about me not handing it in. What I’d found was the eggcase of a nursehound, Scyliorhinus stellaris, also known as the large spotted dogfish which is a type of catshark. (Confusing, I know: a mermaid’s purse from a dogfish catshark. And yes this is still filed under the non-fiction category.)
If you’ve ever seen on the strandline something that looks like a small oblong bubble package of seaweed then what you’ve actually been looking at is the eggcase of a shark or ray. These eggcases are laid on the seabed and act as protective pouches while the embryo develops over several months, emerging as a tiny version of the adult species. They range in size from about four to eighteen centimetres. Some are long and slender (usually a catshark), others squatter (skate or ray). Often they have little horns or tendrils protruding from their corners, and keels or ridges along the side seams. These characteristics can be used to identify from which species the eggcase originated. The Shark Trust have built up a database of eggcase findings which they can use to monitor the numbers and movements of the various species of sharks, skates and rays in the UK’s coastal waters.
I know very little about fish in general and although I know a little more about elasmobranchs – the cartilaginous group of fish that includes sharks and rays – I hadn’t got a clue what a nursehound was before I found and identified that eggcase. Their strange name comes from the old fishermen’s tale that they ‘nursed’ their younger relatives, with the hound part relating to their prior classification as dogfish. Their official label sounds stranger but makes a bit more sense. ‘Scilla’ or ‘Skylla’ in Greek was a sea nymph who was transformed by the witch Circe into a seamonster with six dog heads and who ate seafarers in the Strait of Messina; with ‘rhinos’ being Greek for nose. ‘Stellaris’ is of course Latin for starry, and as the nursehound is covered in spots it’s fairly easy to see where that came from. They are found all round the North Eastern Atlantic, down to the Mediterranean and around the North Coast of Africa. They are a mainly nocturnal species, hiding in rock crevices during the day and hunting by night using their electrosensitive abilities to track down prey.
As a species nursehounds are classified by the IUCN as Near Threatened due to overfishing. Generally in the UK they are mainly a by-catch, but they can be seen on the fish counter as ‘rock salmon’ along with some other smaller catsharks. Their skin used to be sought for ‘rubskin’ as an abrasive and was used similarly to pumice as well as to polish wood and alabaster, to clean beaver hats, and also in the making of arrowheads. Nursehounds are known to use the abrasive properties of their skin as a defensive mechanism when attacked by contracting themselves around the attacker and grating like a rasp to cause injury. They themselves feed on a wide variety of smaller fish, smaller catsharks, crustaceans and cephalopods, and can grow up to 1.6m in length, although the average nursehound is around 1.25m. They are oviparous (they lay eggs) never more than two eggcases at a time and the embryos take 7-12 months to hatch depending on the warmth of the water in which they are incubating – if a netted dog whelk Nassarius reticulatus doesn’t pierce the eggcase during incubation and extract the yolk for food.
It turns out that the River Fal is thought to be a favourite breeding ground of the nursehound ever since marine biologist J. H. Orton’s 1926 research about a mile downstream from the river beach at Channals Creek below Trelissick where I found mine:
During the recent spring tides, the Laminarian zone at Brown Rose Bar-about I mile below Turnaware -was being examined for oysters, and, in an area of not more than 20 square yards, 8 egg-cases of the nursehound containing eggs or embryos, as well as a few empty purses, were found; probably others were on the ground and not seen. Two of these egg-cases had been laid within the last few days, and had the thong-like horny extensions of the corners of the case wrapped round the whole of the anastomosing roots of a bunch of old Laminaria stipes.
Maybe the latest storm had washed up something more exciting than it seemed. Empty vessels are said to make the most noise. But even an empty purse can still hold a great deal between its seams.
Click on the photos for links to more information about them.
If you ever find a mermaid’s purse or an egg case of a shark or ray then it’s really easy to identify it using the Shark Trust key which can be found here. Once you’ve identified what shark or ray belongs to you can then add your findings to the Shark Trust database here.
Or if beachcombing’s not really your thing then take a look at Ted Hughes coastal poetry collection The Mermaid’s Purse, illustrated by Flora McDonnell, which is published by Faber and Faber.
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in which I attempt to trace the less definable perimeter where sea and land meet ecologically by mapping the different types of seaweed along the shoreline.