I’m not sure how I spotted the mermaid’s purse on the strandline of this beach at Kingsbarns near St Andrews, but I think it was the regularity of its shape in amongst the erratic jumble of kelp that first caught my attention.
I crouched down and cradled the mermaid’s purse in my hands. It is such an apt name for these empty pouch-like leathery egg capsules of dogfish and rays. This one belonged to a lesser spotted dogfish and was pale in colour, rectangular and about two inches long, with filamentous tendrils at each corner.
As the eggs are deposited, the female dogfish repeatedly swims round some object such as a clump of seaweed, until the filaments of the capsule become entangled and firmly anchored to the seabed.
Over the course of a few months the embryo gradually develops into a tiny baby dogfish, which will then break free from the protective casing. After stormy weather, these now vacant egg cases are often washed ashore.
A member of the shark family, dogfish are relatively common in our inshore waters, growing up to a couple of feet in length and living on the seabed where they feed upon crustaceans and other small marine creatures.
Dogfish is not a name I particularly like, especially since the prefix ‘dog’ in traditional nature nomenclature is often used in the sense that the species is inferior in some way.
Nowadays there is a trend to call this fish the small-spotted catshark, which has a nicer ring to it. But I’ve always known them as dogfish and find it difficult to change the habit.
I had a most enjoyable day recently trekking up Glen Tilt from Blair Atholl. It is such a magical place, a deep fissure in the landscape stretching for many miles from Perthshire right into the heart of the Cairngorms.
I was on the look-out for golden eagles soaring over one of the high ridges flanking the glen. All the more so because January is a good time to watch eagles engage in their spectacular aerial courtship displays.
The great Scottish naturalist Seton Gordon described how he once saw two eagles ‘meet and perform, without enmity, breath-taking aerial manoeuvres, rising into the clouds, falling through them at tremendous speed, then flattening out and sailing into the wind with wings so steady’.
It is a magnificent sight, but you need the luck to be with you. Although I walked the glen for five hours and scanned the sky continuously, there were, alas, no eagles about. But their absence was compensated by several sightings of ravens, their deep guttural croaks carrying far in the wind. They too are thinking about breeding just now and engage in airborne displays as stunning as any eagle, including barrel rolls where the bird flies upside down.
Seeing these flirty ravens against the snow-patched buttresses of the cold winter glen seemed strangely incongruous and a reminder that spring is not as far away as one might think.
Mermaid’s purses can be found on beaches at any time of the year. Those of rays, such as the thornback ray, are slightly larger than dogfish egg cases and tend to be darker in colour.