Tag Archives: piddocks

Chilly Spring Tides in Looe

I used to think I knew my local rocky shores well, but during this last year of lockdowns and staying local, I have been almost nowhere else. What is remarkable, though, is not the intimacy with which I now know every stone and every overhang, or even the way I like to call on some of the long-term inhabitants, but the fact that, despite the familiarity, there are still surprises on every visit.

Photo by Cornish Rock Pools Junior of the beach looking idyllic – looks can be deceptive: it was freezing!

With a brisk northerly wind counteracting any warmth the sun is trying to put out and a strong swell racing in, the conditions are far from ideal. Other Half and Junior start eagerly enough, discovering some light bulb sea squirts on the edge of a boulder, but even before our film maker friend, Greg, joins us, Junior has taken to sitting at the edge of the pool we are exploring in a largely futile attempt to hide from the wind.

Light bulb sea squirts on a rock covered in bryozoans and spirorbis worms.

“You have to look at this,” Junior calls, holding up a large stone he has found. “I think there are piddocks in it.”

Piddock holes in Junior’s stone.

We peer into the deep, rounded holes in the stone. In one we can see something retreating into the darkness. There are certainly piddocks in there. These odd bivalve molluscs drill into soft rock, boring out deep holes in which they hide, safe from predators.

Weirdly, piddocks are known to have bioluminescence, glowing blue-green in certain circumstances. The rock also looks as though it has been nibbled at by juvenile piddocks or another rock-boring animal. Air-breathing mites have taken up residence in the holes and bristly chitons cling on to the surface.

Bristly chiton on Junior’s piddock rock

Greg arrives to set up, but we’re already feeling the cold and the water is wind-blown and silty from the rough seas. It’s looking far from ideal for capturing the footage of Looe’s amazing marine wildlife that we were hoping for.

Despite our numb fingers we crack on, looking for St Piran’s hermit crabs and fish eggs to film.

We find both, but the crabs are huddled together and hiding in their shells, while the rock goby eggs we find are freshly laid, so aren’t developed yet. In another week or two, hundreds of eyes will gaze out at us, but not today.

Freshly laid goby eggs on the rock

While I can still move my frozen fingers a little, I take photos of a young adult sea hare. It is already many times the size of the juveniles I saw here earlier in the year, and is still putting on weight as it  chomps through the copious supplies of fresh, new-growth seaweeds.

Sea hare (Aplysia punctata)

This sea hare still has some filling out to do, but as though it is keen to prove that it’s already a grown-up, it has laid a tiny patch of its tangled pink spaghetti spawn on the rock.

Sea hare eggs – their spawn looks like pink spaghetti and feels hard to the touch.

The gangly legs of a sea spider catch my eye, flailing about in the seaweed. Ungainly and fragile, it emerges and sways past. A clutch of orange eggs held under its abdomen.

Nymphon sp. sea spider.
The orange mass under the sea spider’s abdomen is the clutch of eggs.

By now the enjoyment we are getting from encountering creatures is fully counterbalanced by the discomfort of being freezing. I am getting the shivers and it is painful to hold my camera in the icy water, but these big spring tides only come a few times a year so we have to try to make the most.

Heading for the lower shore while we can, we slip and slide on the seaweed that covers every rock. We find a pair of small clingfish but they slip away into the weed before Greg can get in position, performing graceful dives off the rock, heads up, backs arched, like parachutists in freefall. They are so well camouflaged in the pool that we stand no chance of finding them again.

I only see this little clingfish for a few seconds before it dives off the rock.

In the nearby pools I find green shore urchins, chitons and hydroids. This area is rarely out of the water, so is rich and stable with a diverse array of marine life. Some of the nearby rocks are often targeted by people equipped with spikes foraging mainly for crustaceans. The foragers often leave a trail of destruction: stones and seaweed are tossed aside as they go, their metal tools scrape and damage the soft-bodied animals that live on the rocks and if they find any large animals, they take them home to eat.

Green shore urchin with tube feet extended. Animals like these are easily damaged or lose their safe hideaways if poeple move their rocks.

Like other conservationists, I put a lot of energy into studying the ecology of my local patch and into teaching others to love and care for our wildlife. It breaks my heart to see others entering the environment only to destroy it with little regard to sustainability. With the rise of videos promoting taking wild animals from the shore, I find myself having to be increasingly careful not to share any images of commercial species in case it leads to them being targeted. Foraging may have a lower impact on the marine environment than trawling and industrial fishing and has always happened to some degree, but the number of foragers is growing and the impact is not negligible.

There are many soft-bodied animals on the shore, like this daisy anemone with its beautiful purple mouth.

Although people are only officially allowed to remove certain species of crustaceans above a minimum size, this is not enforced by anyone and it seems there are no controls on foraging for ‘personal consumption’, even in a Marine Conservation Zone. These sheltered intertidal pools are an important nursery for young crabs, so minimising disturbance here is important to maintain stocks, as well as for the rest of the ecosystem.

Today I’m relieved to see no sign of foragers. The uncomfortably cold weather is keeping people away, keeping the animals safe. The thought warms me a little.

This ‘White-ruffed’ Aeolidiella alderi sea slug had recently eaten a daisy anemone and taken on the anemone’s colours.

Back to the pools and I am excited to find a slender purple whelk on a tuft of red seaweed. This elegant Raphitoma purpurea is the first live one I’ve found on this stretch of rocks. The shell is striking with its criss-cross of sculptured lines and deep red-purple colour, marked here and there with splashes of white.

Raphitoma purpurea – a purple whelk.

The snail has fully extended with its purple-spotted proboscis and is exploring the pool, its dark eyes contrasting starkly with its pearly white body. I spend as long as I can quietly watching it gliding along, feeling its way.

Purple whelk, Raphitoma purpurea, exploring the pool with its fabulous proboscis.

Despite the cold, the wind and the shivers, the day is far from wasted and this is just the start of a week of super-low tides. Once again, the beach has offered up something new.

Photo by Cornish Rock Pools Junior – me near my purple whelk. Proudly unglamorous as always!

If you are visiting the Cornish Rock Pools, find out how to discover lots of amazing creatures safely and sustainably with my beginner’s guide.

The Surprising Mini-World of Rock Pool Insects

If my blog posts have seemed a bit thin on the ground the last few months, it’s fair to put the blame on Atiyah, Brendan, Ciara and Dennis.

Even on the good days the lighting and conditions have been less than ideal so, to make the best of a mediocre tide, I enlisted the help of Other Half. Together, we could look under the sort of rock I usually see but leave alone, knowing it weighs far more than I do.

This short video shows you some of the animals living there…. read on to find out more.

Other Half was pleased with the strawberry anemones, which were enormously plump with all their tentacles retracted.

Strawberry anemone
Strawberry anemone

Under a carefully constructed shelter made of small stones and pieces of kelp we could also see the purple-tipped spines of a green shore urchin. Among its many disc-topped tube feet, a long polychaete worm was exploring.

Green shore urchin
Green shore urchin

What drew my eye most, though, were the holes in the rock. These were scattered across the surface of the rock and about the circumference of a pencil. I caught the tiniest glimpse of movement as I looked into one of them.

Piddock holes underneath the boulder.

If I were the BBC Natural History Unit, I’d have filmed inside with an endoscope or transported the rock to deeper water so I could photograph the gaping shells emerging to feed.  Instead, you will have to take my word for it that there were piddocks in those holes!

Piddocks are bivalve molluscs (clam shells), which burrow into the rock and spend their entire lives in their holes.

A rock with this many cracks and holes in it is bound to contain some good hiding places for other animals and also some air pockets, which enable some of our most unlikely rock pool wildlife to survive being submerged twice a day. Some insects and other arthropods that breathe air live here, but you have to be patient to see them.

I settled down with my camera and before long, the first waggling antennae of a springtail poked over the rim.

The end of a piddock protruding from a hole. (Taken on another occasion).

I often see rafts of blue-grey Anurida maritima springtails floating on the surface tension of pools in the summer, but these were smaller still and so pale they looked almost transparent. They are clearly visible in the video but I could only take very blurred still photos.

The fabulous Essential Guide to Rock Pooling by Steve Trewhella and Julie Hatcher was my first port of call in trying to identify them. The book has great photos and plenty of clear information on what to look for. Steve kindly identified these springtails as Axelsonia littorlis – a new species to me. It’s amazing what you find when you stop to look.

The best shots I could get were of a larger bug called Aepophilus bonnairei, a beetle-like creature with red eyes and a spiky coat of hairs around its back and legs. These hairs trap air bubbles, which help the insect to breathe when it is submerged.

Aeopophilus bonnairei bug on a rock
Aepophilus bonnairei bug on a rock
A juvenile Aepophilus bonnarirei.

Time was short as the tide was already turning and the waves were pounding in. I tried to photograph as many species as I could so that I could put records together afterwards. Some, like the painted top shells and the various crabs, are easy to identify.

This image has an empty alt attribute; its file name is between-plaidy-and-millendreath-january-2020-painted-topshell.jpg
Painted top shell.

One of the most striking sponges I see on the shore is the vivid blue Terpios gelatinosus. Many other sponges are harder to identify confidently.

Blue sponge - Terpios gelatinosus with keel worm
Blue sponge – Terpios gelatinosus – with keel worm

It seemed that no part of this valuable habitat was left unoccupied. To avoid any of these creatures coming to harm, we gently manoeuvred the rock back in place well before the surging waves reached us.

Different coloured patches of star ascidian among spirorbid worms, keel worms and other life on the boulder.

As always, I was left in utter awe of the fragile little creatures we saw.

It is remarkable that these animals will cling onto life here no matter how much the wind howls and the sea roars around them, while we head home to bring the plant pots in out of the wind, check the fences and put the kettle on.

Broad-clawed porcelain crab
A grey and windy day on the shore. It’s incredible that anything can survive in these pools, especially insects.