A predator among the fish eggs: Calma gobioophaga sea slug

If you read this blog regularly, you’ve probably noticed a pattern: I bimble about the Cornish rock pools looking for an exciting creature, fail completely, then find something unexpected. Well, hopefully you like the format because this week is no exception. I go on a quest to find fish eggs and discover this rare sea slug.

Fish eggs are amazing. If you catch them just as they’re nearing hatching you can see each baby fish staring out, its tail curled tight around its head like a scarf.

So, when Junior announces he wants to go for a big walk, I suggest Port Nadler. This slightly exposed rocky bay is ideal for Cornish clingfish. Their distinctive yellow eggs usually carpet the underside of the rocks and their developing babies are especially beautiful.

Clingfish eggs - with one newly-hatched fish (centre)
Clingfish eggs – with one newly-hatched fish (centre)

Only the tide today isn’t low enough to access the clingfishes’ favourite gully.

I look in the pools and lose count of how many rocks I lift. There don’t seem to be any fish eggs. As the tide drops a little further, I come across some Berthella plumula sea slugs and a sea hare.

A pair of Berthella plumula sea slugs
A pair of Berthella plumula sea slugs

There’s an anemone I don’t recognise. Translucent white all over with a base so wide it looks like a bowl. I later realise it must be the white form of Sagartia elegans (var. nivea).

Sagartia elegans (var nivea) anemone
Sagartia elegans (var. nivea) anemone

Junior finishes his digging in the sand at the top of the beach and wanders over to join me. We lift a rock together and finally here are some eggs. They’re not the yellow clingfish eggs I was looking for, they’re smaller goby eggs, forming black-specked carpet of grey. Under the camera, the specks become a sea of eyes looking up at me.

It takes me a long time to decide that the Calma gobioophaga sea slug (in the background here) is 'a thing'
It takes me a long time to decide that the Calma gobioophaga sea slug (in the background here) is ‘a thing’

I remember rockpool expert David Fenwick, who runs the fabulous Aphotomarine site, telling me a year or two back that there was a species of sea slug that specialises in eating these eggs. I peer into the greyness and see nothing, apart from a thin yellowish patch in the centre which looks like a piece of sponge or sea squirt.

I look some more. The eggs around the edge of the yellow patch look longer than the others.

I stare, stare some more then focus my camera on the patch and do yet more staring. Even then I’m not sure, but it could be…

It’s only when I see a tentacle move that I begin to see the slug properly. It’s over a centimetre long, but most of its body is covered in pointed cerrata the colour and shape of goby eggs, right down to the black dots that ressemble eyes.

Calma gobioophaga on its goby egg prey, its eyes showing through behind its long rhinophores.
Calma gobioophaga on its goby egg prey, its eyes showing through behind its long rhinophores.

This is the weirdly named Calma gobioophaga egg-eating sea slug. It’s the first I’ve seen and only the second record of this species in Cornwall.

The yellowish patch I thought was a sea squirt is the slug’s back. It’s covered in pale circles, which my books tell me afterwards are the mature gonads. Who’d have thought?

The books also tells me that the slug absorbs the fish eggs so well into its gut that it has no need of an anus. That’s right; it doesn’t poo. I’m not sure how that works, but it’s the sort of fact that gets Junior’s attention.

Calma gobioophaga - the cerrata (tentacles) on its back blend perfectly with the goby eggs. Only the pale circles on its back (gonads) stand out.
Calma gobioophaga – the cerrata (tentacles) on its back blend perfectly with the goby eggs. Only the pale circles on its back (gonads) stand out.

It’s not the easiest thing to photograph: a grey blob on a mat of grey eggs on a grey day in silty water. As I start to get my eye in to the outline of the slug, it glides towards me, feeling the eggs with its tentacles and swinging its long rhinophores forwards.

Tucked immediately behind each rhinophore is a distinct black eye, one of the characteristic features of this species.

Calma gobioophaga on goby eggs (probably the eggs of a rock goby) near Looe, Cornwall
Calma gobioophaga on goby eggs (probably the eggs of a rock goby) near Looe, Cornwall

The books suggest this species only eats the eggs of the black goby (Gobius niger), but slugs are not great readers and the other records from Cornwall and Brittany are, like this one, probably on rock goby (Gobius paganellus) eggs. In the Mediterranean this species has also been recorded on giant goby (Gobius cobitis) eggs. There’s another, closely related, species of sea slug, Calma glaucoides, that feeds on a wider range of eggs, including clingfish eggs and has been recorded in Cornwall too. Hopefully I’ll find that one soon!

The slug’s life cycle intigues me. As fish eggs are available for such a short period of the year, I’m not sure what happens to these slugs during the remaining months.

It comes on to rain heavily and as we’re already soaked from exploring the rock pools, we call it a day. I haven’t found a single clingfish egg, but, as is the way with rockpooling, I’ve discovered something even better.

Discoveries on my Doorstep – Day Two (Hannafore, Looe)

Fairer conditions set in for the second day of rockpooling with the fabulous David Fenwick and the Coastwise North Devon team. Without the challenges of wind-blown pools and rain-spattered lenses to contend with, the day promises to be even more inspiring.

Martin holds a spiny starfish, Hannafore, Looe
Martin holds a spiny starfish, Hannafore, Looe

I’ve managed to replace Cornish Rock Pools Junior’s leaky wellies so he joins us to track down amazing creatures. Today we will focus on the lagoon and seagrass beds at Hannafore and I have no doubt I’ll be seeing something new.

Junior gets stuck into the task at hand; head down, bottom up, staring into the glassy water. He shrieks and comes wading over to me, taking care not to spill water from his precious tub. In it he has a plump sea slug, a ‘Great grey’ Aeolidia papillosa – or sheep slug as we call them.

Junior's 'Sheep slug' - Aeolidia papillosa - looking very fluffy
Junior’s ‘Sheep slug’ – Aeolidia papillosa – looking very fluffy

It’s a rusty colour from eating anemones and I’m allowed to stroke it. “It feels barely there, like air,” Junior explains. He looks after it for some while before returning it to the exact spot he found it.

I sight a little yellow blob and pop it in a plastic tube, expecting it to be a Lamellaria mollusc. A few minutes later it’s sprouted rhinophores on its head and is circling the tube like a hamster in a wheel. It’s a Jorunna tomentosa sea slug.

Jorunna tomentosa sea slug, Hannafore, Looe
Jorunna tomentosa sea slug, Hannafore, Looe

Meanwhile, David Fenwick is making amazing finds. He’s especially interested in the small spider crabs today and is keen to identify some more species. It pays off – by examining one under a microscope before returning it to the shore he discovers an Achaeus cranchii, last recorded in 1909. David has posted his fantastic photos on his site Aphotomarine here: http://www.aphotomarine.com/crab_achaeus_cranchii.html

A small spider crab - there are several species in Looe including some rare ones as we found out!
A small spider crab – there are several species in Looe including some rare ones as we found out!

Someone points out these stunning Eubranchus faranni sea slugs to me. They’re some of the most spectacular little nudibranchs I’ve ever seen. Although their body shape is the same, the two slugs are entirely different colours: one orange, one black. Both are feeding on hydroids (the tiny fern-shaped animals that you can see on the seaweed).

Eubranchus faranni sea slug feeding on hydroids, Looe
Eubranchus faranni sea slug feeding on hydroids, Looe
A more typically coloured orange Eubranchus faranni, Looe.
A more typically coloured orange Eubranchus faranni, Looe.
The black Eubranchus faranni sea slug showing the orange markings on its back.
The black Eubranchus faranni sea slug showing the orange markings on its back.

We all keep an eye out for baby cat sharks as this area is a nursery for their egg cases and we often see hatchlings this time of year. Rob spots one, a recently hatched greater spotted catshark (Scyliorhinus stellaris) and we all gather to look at it. Junior touches its rough back and watches it swim a short distance.

The baby catshark, Scyliorhinus stellaris, resting on the bottom of the pool.
The baby catshark, Scyliorhinus stellaris, resting on the bottom of the pool.
Catshark, Scyliorhinus stellaris, Hannafore, Looe.
Baby catshark, Scyliorhinus stellaris, Hannafore, Looe. These sharks have skin that feels like sandpaper, but is very hydrodynamic.

When the tide turns we start to make our way back to shore; the water floods in quickly across these shallow lagoons and can easily catch you out. As usual, this is the moment when I make my best find. I’ve just said to Jan from Coastwise how nice it is not to look at stalked jellyfish, which, pretty as they are, are frankly becoming a bit tedious after a whole winter of dedicated surveys to record them. Then something catches my eye.

Stalked jellyfish (Calvadosia cruxmelitensis) conjoined twins.
Stalked jellyfish (Calvadosia cruxmelitensis) conjoined twins.

Yes, it’s a stalked jellyfish, but this one is different. It’s a Calvadosia cruxmelitensis, always a pretty species, only it appears to have a reflection behind it, an exact mirror image. Closer inspection confirms that this is a double-headed stalked jellyfish, the first I’ve ever seen. Jan and I take photos as the tide creeps up our boots.

My first double-headed stalked jellyfish (Calvadosia cruxmelitensis), Looe
My first double-headed stalked jellyfish (Calvadosia cruxmelitensis), Looe

After hours wading through the water, bending down, climbing over rocks and lifting stones, we’re all slump down, exhausted onto the pipeway to munch a late picnic lunch and swap notes while the tide pushes in around our feet.

By sharing our finds and knowledge we’ve all seen new things and I’ve learned a huge amount about this familiar shore.

A tortoiseshell limpet
A tortoiseshell limpet
A beautifully 'fluffy' isopod - Cymodice truncata male I think.
A beautifully ‘fluffy’ isopod – Cymodice truncata male I think.
A toothed crab (Pirimela denticulata), Hannafore, Looe
A toothed crab (Pirimela denticulata), Hannafore, Looe
Blue-rayed limpet, Hannafore, Looe
Blue-rayed limpet, Hannafore, Looe
Daisy anemone, Hannafore, Looe
Daisy anemone, Hannafore, Looe
A very well-fed Aplysia puncata sea hare
A very well-fed Aplysia puncata sea hare

Discoveries on my Doorstep – Rockpooling with the experts in Looe (Day 1)

There’s a questionable theory that 10 000 hours of practice makes you an expert and I may be close to ‘doing my time’ in the Cornish rock pools by now. However, I often feel I’m only scratching the surface of what’s out there. What better then, than to spend a few days on the shore with the genius that is David Fenwick, creator of Aphotomarine together with a fabulous group of fellow rockpool fanatics from Coastwise North Devon?

With layers and waterproofs aplenty, Junior and I joined them at Hannafore Beach, a site I know intimately, to see what new discoveries might await us.

 I realised within minutes that I should have brought a notebook. David’s knowledge of marine species is immense and he wasted no time in finding signs of nematode worms living inside seaweed, reeling off their names. It was windy, drizzling and cold and to make matters worse Junior sprung a leak in his wellies, but there was no doubt this is going to be a fascinating day. Leaving Junior playing at reconstructing ancient ruined cities from the rocks of a mid-shore ridge, we waded across the lower shore.

Sea hares (Aplysia punctata) were everywhere munching on the seaweed.
Sea hares (Aplysia punctata) were everywhere munching on the seaweed.

Some species were familiar. The sea hares were everywhere and so abundant that it was impossible to avoid them. This swirling cloud of purple ink in the water was a sign we’d accidentally disturbed one of them.

We must have accidentally disturbed a sea hare (Aplysia punctata), making it release a cloud of purple ink.
We must have accidentally disturbed a sea hare (Aplysia punctata), making it release a cloud of purple ink.

Although Greater-spotted catshark (Scyliorhinus stellaris) egg cases are commonly found on parts of Hannafore we found more than I’ve seen before in this particular area, suggesting the nursery is more extensive than I’d realised. The eggs were at various stages from recently laid, smooth cases to bio-encrusted cases that had been in the water for months and seemed close to hatching.

A recently-laid catshark eggcase clearly showing the yolk sac inside
A recently-laid catshark eggcase clearly showing the yolk sac inside

Rob from Coastwise North Devon made one of my favourite finds of the day, this hairy hermit crab, Pagurus cuanensis, had some of the hairiest knees I’ve seen in a while.

Pagurus cuanensis, the 'Hairy hermit'.
Pagurus cuanensis, the ‘Hairy hermit’.

David Fenwick was finding creatures at a dizzying rate. The speed with which he could pick out and name the different animals under each boulder was incredible.

Boring sponge under a boulder
Boring sponge under a boulder
A Calvadosia cruxmelitensis stalked jellyfish
A Calvadosia cruxmelitensis stalked jellyfish

Wading through the myriad colours of the seaweeds and past the many pretty Calvadosia cruxmelitensis stalked jellyfish clinging to them, we came to some rocks that are exposed to more current than some other parts of the beach. (Check out David’s brilliant Stauromedusae site to find out more about stalked jellyfish),

Under a deep overhang where I sometimes see lobsters, there was a small cluster of green and turquoise jewel anemones. They look more impressive when they’re open underwater, with little beads on the end of each tentacle, but I love the colours.

Jewel anemone
Jewel anemone

After a while, I spotted a colourful squat lobster, Galathea strigosa, scuttling across the back of an overhang and dived headlong in to retrieve it.

Galathea strigosa - the Spiny squat lobster
Galathea strigosa – the Spiny squat lobster

The wind on the pools was making it difficult to see much and my camera lens was steamed up, but we crammed in a last few minutes of rockpooling, looking at sea slugs, fish and hermit crabs before calling an end to day 1.

Aeolidella alderi sea slug - this slug looks similar to the common grey (Aeolidia papillosa) at first sight but is more slender with a white 'ruff' of cerrata at its neck.
Aeolidella alderi sea slug – this slug looks similar to the common grey (Aeolidia papillosa) at first sight but is more slender with a white ‘ruff’ of cerrata at its neck.
The more common great grey sea slug (Aeolidia papillosa) looking like it has probably just guzzled a red anemone!
The more common great grey sea slug (Aeolidia papillosa) looking like it has probably just guzzled a red anemone!
An Anapagurus hyndmanni hermit crab.
An Anapagurus hyndmanni hermit crab.
Montagu's sea snail (a fish)
Montagu’s sea snail (a fish)
A small spider crab (Macropodia sp. I think...) - David found did an amazing job of identifying a few of these tiny crabs to species level.
A small spider crab (Macropodia sp. I think…) – David found did an amazing job of identifying a few of these tiny crabs to species level.

Coming soon – Part 2 of rockpooling with the experts!

Cross-Border Rockpooling with the Porcupine Marine Natural History Society

It sometimes feels like I don’t get out much – either socially or out of the county (Not that it’s a hardship to be in Cornwall!). So, I could barely contain my excitement at having the opportunity to attend the Porcupine Marine Natural History Society Conference in Plymouth. I packed my passport and set forth across the Tamar.

Not only did I mingle with the most amazing bunch of fellow marine wildlife obsessives and hear their latest findings, but the third day of the conference was spent rockpooling at Wembury in South Devon.

 

A prickle of Porcupines at work
A prickle of Porcupines at work at Wembury, Devon

While the environment at Wembury is similar to my home patch in South East Cornwall, a major difference is that Wembury has a marine centre, staffed by lovely people from the Devon Wildlife Trust. The centre promotes marine conservation and runs all sorts of public and educational events. It also provided a handy indoor base to set up some microscopes and a refreshment station. Luxury after my recent all-weather forays!

Coral, from the Marine Centre, was especially interested to know of any stalked jellyfish finds as past records suggest they used to be more abundant. Having spent the last few months doing stalked jellyfish surveys, I was starting to see them in my sleep, so I was happy to take a look.

Sure enough, there were plenty of stalked jellyfish there, the lower shore pools and gullies were ideal for them. One small clump of seaweed I looked at had six Calvadosia cruxmelitensis on it.

Calvadosia cruxmelitensis stalked jellyfish at Wembury, Devon
Calvadosia cruxmelitensis stalked jellyfish at Wembury, Devon

I also found several Craterolophus convolvulus, a species that I see less frequently, although it does occur in my home patch. It looks like it has four twisted coils of rope running down to the centre and has a wide base with a goblet-like profile.

A Craterolophus convoluvulus stalked jellydish at Wembury, Devon
A Craterolophus convoluvulus stalked jellydish at Wembury, Devon

 

Side view of a Craterolophus convolvulus stalked jellyfish at Wembury, Devon
Side view of a Craterolophus convolvulus stalked jellyfish at Wembury, Devon

This was my first visit to Wembury and I couldn’t bring myself to spend all my time looking at stalked jellyfish, lovely though they are. Having established there were lots of them, I set my mind to other things. 

Spotting a patch of a thick green, finger-like seaweed, Codium. I looked for the wonderful Photosynthesising sea slug (Elysia viridis). All my books say it loves nothing better than this seaweed, but so far I’ve always found them on other things. Today, for the first time, I discovered one that had clearly read the same book as me.

An Elysia vididis sea slug showing off its bright green spots and eating Codium seaweed just like it's supposed to!
An Elysia vididis sea slug showing off its bright green spots and eating Codium seaweed just like it’s supposed to!

These slugs retain chloroplasts from their food in their bodies, where they carry on photosynthesising to provide the slug with energy or other benefits. This one wasn’t a particularly vivid green, but it’s still pretty amazing to see a solar powered slug. 

Slugs were plentiful elsewhere on the shore too, although I didn’t come across anything particularly unusual. I loved this frilly little pair of Goniodoris nodosa.

Goniodoris nodosa sea slugs at Wembury, Devon
Goniodoris nodosa sea slugs at Wembury, Devon
A frilly sea slug - Goniodoris nodosa - at Wembury, Devon
A frilly sea slug – Goniodoris nodosa – at Wembury, Devon

This Berthella plumula was exploring the rocks and I saw the spawn of several species of sea slug, so there will soon be babies about!

Berthella plumula sea slug at Wembury, Devon
Berthella plumula sea slug at Wembury, Devon

In February, the only sea hares I could find were a few millimetres long. Today they’re several centimetres long and developing their adult leopard-spot colours.

Sea hare (Aplysia punctata) growing nicely at Wembury, Devon
Sea hare (Aplysia punctata) growing nicely at Wembury, Devon

The small clingfish species were abundant, but I didn’t attempt to check their teeth to see which species they were!

The books say to check the species by checking the teeth - not easy with a tiny clingfish like this one!
The books say to check the species by checking the teeth – not easy with a tiny clingfish like this one!

 

A small clingfish species (small headed or two-spot) at Wembury, Devon
A small clingfish species (small headed or two-spot) at Wembury, Devon

This male worm pipefish looked smart in his limpet-hat. He was carrying eggs in his belly-groove so I popped him straight back in his pool. 

Male pipefish with eggs wearing a limpet-shell hat at Wembury, Devon
Male Worm pipefish with eggs sporting a limpet-shell hat at Wembury, Devon

As you’d expect, there was no shortage of crabs. This tiny Anapagurus hyndmanni hermit crab caught my eye as it scuttled across the sand. They don’t grow more than about a centimetre long, but their right claw is about as long again and looks it’s wearing a huge white boxing glove. There were several around once I got my eye in.

Hermit crab (Anapgurus hyndmanni) showing it's huge white claw.
Hermit crab (Anapgurus hyndmanni) showing its huge white claw.

 

Anapagurus hyndmanni hermit crab at Wembury, Devon
Anapagurus hyndmanni hermit crab at Wembury, Devon

It was wonderful to share finds with other ‘Porcupines’, as members of the society refer to each other. The society is named after HMS Porcupine, although I’m more than a little vague as to why! One unusual discovery was this purple whelk, Raphitoma purpurea.

Raphitoma purpurea shell at Wembury, Devon
Raphitoma purpurea shell at Wembury, Devon

Inevitably I got carried away on the shore and didn’t think to have lunch until the tide was washing over my boots. By the time I’d gulped down a sandwich and some delicious M&S chocolate tiffin (a perk of having visited Plymouth!), all the Porcupines were assembled in the Marine Centre swapping notes and checking identifications. After a very pleasant half-hour checking other people’s stalked jelly photos and generally enthusing, it was time to cross the border back to Kernow once more.

I might not get to meet up with everyone like this very often – I’m pretty unlikely to make it to the next event in Newcastle for obvious reasons – but it’s inspiring to feel part of a national network of people who are all passionate about the same things as me.

So, a huge thank you goes to all the ‘Porcupines’ for making me welcome at my first conference, to Wembury Marine Centre and to my other half and Cornish Rockpools Junior for being patient with me while I nattered for hours about marine creatures with my new friends.

 Thanks also to you for sharing my adventures. Bonus photos follow for reading this far!

A lovely yellow Ophiothrix fragilis brittle star at Wembury, Devon
A lovely yellow Ophiothrix fragilis brittle star at Wembury, Devon
Close-up of a spiny starfish arm, Wembury, Devon
Close-up of a spiny starfish arm, Wembury, Devon
A black brittle star (Ophiocomina nigra) at Wembury, Devon
A black brittle star (Ophiocomina nigra) at Wembury, Devon
A Cornish clingfish over the border in Wembury, Devon
A Cornish clingfish over the border in Wembury, Devon

Happy rockpooling everyone!

All-Weather Rock Pooling

Much as I love the Cornish rock pools, there are times – throughout the year – when the conditions are grim. According to the forecast, today is going to be one of those days. I have reluctantly cancelled a meet-up with Junior’s friends because the charts show the sort of gales and lashing rain that have most little kiddies shivering before they even reach the pools.

I don’t want to make rockpooling a traumatic experience for other people’s children, but I don’t think Junior’s aware that staying in is an option. He’s so well trained to enjoy the misery that at 10am he’s merrily pulling on waterproofs and wellies and grabbing a bucket. We’re off to ‘the gully’ and no amount of buffeting winds or ominous clouds are going to stop him.

Junior's training in rockpooling in all weathers started early - out with Countryfile age 3
Junior’s training in rockpooling in all weathers started early – out with Countryfile age 3

We are climbing across the rocks from Plaidy beach towards our favourite spot when hail starts ricocheting off our buckets. We keep our heads down, turning our attention to the variety of colours in the pebbles. Junior crams his pockets with his favourites, the extra ballast helping to keep him upright against the howling wind.

The rocky gully is a little more sheltered if you crouch low enough. I adopt a sumo stance and waddle around checking rocks. Every single one conceals groups of worm pipefish, their bodies tangled together.

Entwined worm pipefish couple, Looe.
Entwined worm pipefish couple, Looe.

I’m taking photos of a blob, which is a stalked jellyfish marooned above the water-line by the big tide, when Junior announces it’s time to go ‘mountaineering’.

Out of the water, stalked jellyfish just look like blobs. Calvadosia cruxmelitensis, Looe
Out of the water stalked jellyfish just look like blobs. Calvadosia cruxmelitensis, Looe

I feign deafness for a few more minutes, looking at crabs and urchins, but he’s persistent and soon I’m scrambling up a slope in the rock and attempting to follow him as he leaps across the sharp ridges and shoots down the steep seaweed-covered slopes to the next gully.

A handsome Xantho incisus crab, Looe
A handsome Xantho incisus crab, Looe
A green shore urchin half-hidden by the shells, seaweeds and pebbles among its spines, Looe
A green shore urchin half-hidden by the shells, seaweeds and pebbles among its spines, Looe

The low pressure and large waves are keeping the tide from falling as far as it might otherwise, so I’m wading to the top of my wellies when I find this sea slug, a Limacia clavigera. On the rock it’s formless, so I pop it in some water to take photos.

Limacia clavigeira, the orange-clubbed sea slug. In the water its vivid rhinophores and markings are stunning.
Limacia clavigeira, the orange-clubbed sea slug. In the water its vivid rhinophores and markings are stunning.

Junior returns from his latest expedition across the rocks telling me there’s ‘something I have to see.’ Inevitably, his find involves more climbing and some perilous leaps, which are a challenge in my clunky wellies.

The narrow gap in some huge rocks he’s discovered looks promising and Junior assures me it’s the most sheltered place on the beach. I suspect this might be a good spot for Devonshire cup corals and some other species which like strong currents. I won’t find out today though. The waves are exploding through the gap and the water in front of me is chest-deep.

We explore the pools. A rockling is splashing among the kelp and on the overhang, an Arctic cowrie is grazing. The damp weather suits shore creatures just fine.

Arctic cowrie, Looe
Arctic cowrie, Looe

The tide is due to turn so we start to gather up our things. When it starts to hail once more, I abandon taking photos of a beautifully decorated little spider crab and we clamber up the narrow cliff path.

A small species of 'decorator' spider crab
A small species of ‘decorator’ spider crab

As the downpour slows, we take a breather and look back over the rocks we’ve explored. The beach is completely empty, except for a pair of calling herons flying over. Somewhere a lone oystercatcher is trilling away. Despite his coat being wet enough to wring out (and I suspect his socks are too…) Junior declares the expedition a success.

I don’t know where he gets it from…

It's not a proper day out if there's no water on the lens!
Like mother, like son… It’s not a proper day out if there’s no water on the lens!

A Window to the Underwater World

The pools sparkle as the sun finally shoulders its way through the February murk. Beneath the surface, the seaweeds are sprouting up, the first sign of spring in the rock pools, and with them come the sea slugs. Many of these minute molluscs choose to spawn in the shallow waters around the shore, where their favourite foods such as sponges, sea squirts and seaweeds are abundant.

A baby sea hare, Aplysia punctata, grazing on seaweed.
A baby sea hare, Aplysia punctata, grazing on seaweed.

How they travel such distances to find mates and lay their eggs here is something of a mystery to me. They are delicate, squishy little things at best, and mere blobs of jelly out of the water. Once in the water, though, they reveal their colours and shapes, and most rockpoolers delight in finding them. Today, I see mostly pale, blobby ones rather than their spectacular cousins, but they are intriguing nonetheless.

I have ventured down a rocky gully that’s rarely accessible due to the pounding waves that surge through it. The overhangs are studded with Scarlet and gold cup corals, pinpricks of the brightest orange. Up close, I admire their translucent tentacles, wedging my head into the rocks to secure a better look.

The striking colours of the Scarlet and gold cup coral.
The striking colours of the Scarlet and gold cup coral.

Today, the unusual wind direction is keeping the waves at bay – just. The swell bubbles through a channel at my feet and every now and then spray is flung across the rocks onto my back. Places like this make me nervous and I’m constantly checking over my shoulder, expecting to be swept off into the Atlantic. As always, I forget all this as soon as I see an interesting creature.

Abundant Scarlet and gold cup corals line the overhanging rocks
Abundant Scarlet and gold cup corals line the overhanging rocks

In a hole under a rocky ledge beside a long pool is a white spiral of jelly. These are sea slug eggs and I know whatever laid them must be close by. After a minute of searching, I spot a blob on the rock and, taking great care not to squash it, I take it in my hand and pop it in a tub of water.

Before my eyes, the blob starts to unfurl. Its body takes on a more definite form and feathery antennae (rhinophores) extend from its forehead, while a frilled ruff of gills fans out of its back. Although it’s hardly the most colourful of the sea slugs, its creamy-white body has a pearly quality and its undulating sides make it look like it’s wearing layers of petticoats under its mantle. I am so absorbed in watching it I almost don’t notice the movement in my peripheral vision.

The Goniodoris nodosa sea slug shows its frills once in the water
The Goniodoris nodosa sea slug shows its frills.

When I do look up, I almost slip off the rock in surprise. Emerging in a slow glide from its cave at the back of the pool are two vast black claws, followed by legs of a striking blue. Long red antennae are stroking the surface of the pool and I find myself staring into the eyes of a fully-grown lobster.

Bob the lobster in the rock pool, Cornwall
Bob the lobster in his/her rock pool, Cornwall

I’m sure you know as well as I do that lobsters don’t eat wellies, but when you’re on your own in a remote spot and one’s marching determinedly towards your toes, you start to question these things.

As your intrepid reporter from the Cornish rock pools, I know I mustn’t snatch my welly out of the pool, where it is dangling in front of those strong claws. Instead, I lower the container holding the sea slug onto the rock, flick my camera off the macro setting and start taking photos. I even manage a short video while the lobster, deciding that my boot doesn’t look tasty after all, backs into its hole and is soon lost from sight.

Moments like this take my breath away as only a close encounter with the natural world can. I remain staring into the pool for some time, a window into another world, until the rumbling waves remind me that it isn’t safe to linger here. Soon the tide will cover this pool and all its secrets once more.

Note: I have deliberately avoided specifying my location this week to keep Bob the lobster safe from harm!

The Stalked Jellyfish World Record (for Portwrinkle)

“So is this a world record?” Cornish Rock Pools Junior has just found 26 stalked jellyfish and is feeling rightly proud of himself.

“It’s a record for Portwrinkle,” I tell him. “They’ve never been found here before.”

“But is it a world record?” he insists.

I take a moment to consider this. Only a moment, because my hands are frozen from holding my camera in the water and another snow flurry is starting.

“Yes,” I say. “You now have the world record for finding stalked jellyfish in Portwrinkle.”

From the leaping and cheering, I’d guess he’s satisfied with that.

Cornish Rock Pools Junior searches for stalked jellyfish at Portwrinkle
Cornish Rock Pools Junior searches for stalked jellyfish at Portwrinkle

If you follow this blog regularly, you may be starting to find the recent focus on stalked jellyfish a touch tedious. You wouldn’t be alone. Although I remember the excitement of finding my first one, the beauty of its markings and delicate tentacles, after seeing scores of the things and spending hours in freezing pools staring into the seaweed, they’re losing their edge.

Still, given that one species is a recognised feature of my local Marine Conservation Zone and two more species have potential to be added, any evidence that they’re here might help to protect them. So far, all of that evidence has come from beaches in walking distance of my home in Looe because I’m pretty much the only person recording them. When I took Natural England on a stalked jelly hunt at Hannafore, they asked if I could help them search beaches at the opposite end of the Looe and Whitsand Bay Marine Conservation Zone.

An adult Haliclystus ocroradiatus with a baby next to it. This species is a recognised feature of the Looe and Whitsand Marine Conservation Zone.
An adult Haliclystus ocroradiatus with a baby next to it. This species is a recognised feature of the Looe and Whitsand Marine Conservation Zone.

It seems such a great idea. Leaving home in a snow flurry though, I begin to question my sanity. I’m not sure, in such circumstances, whether it’s a good thing to have a wonderfully supportive partner and son, but neither of them bat an eyelid at the weather. Wearing boots, waterproofs, scarves, hats, gloves, and just about every item of clothing we possess, we head for Portwrinkle beach.

Junior becomes less supportive when I find the first stalked jelly. I hadn’t realised how badly he wanted to find it himself and wish I’d kept quiet about it, but after 45 minutes of fruitless searching it seemed like the sort of breakthrough worth announcing.

The first find is a Haliclystus octoradiatus - the 'blob' (primary tentacle) between each pair of tentacle arms helps identify this species.
The first find is a Haliclystus octoradiatus – the ‘blob’ (primary tentacle) between each pair of tentacle arms helps identify this species.

“I’m useless,” he sighs. “Now I won’t get the world record.”

I try to reassure him. Surely we are a team and finding them together? But nothing is working. A little further down the rocks, where the pools meet the sea, I notice an arc of rocks forming a shallow, rock strewn bay with plenty of weed.

“Come and try over here,” I suggest.

He kicks at the rocks and mopes over to where I’m standing.

“Just try,” I repeat.

It only takes a second.

“Here’s one,” he screams, his voice easily reaching his Dad, in the distance across the rocks.

One of Junior's many, many finds. A Calvadosia cruxmelitensis stalked jelly. The white spots (which are stinging cells) trace the outline of the tentacle arms and form a 'Maltese cross'.
One of Junior’s many, many finds. A Calvadosia cruxmelitensis stalked jelly. The white spots (which are stinging cells) trace the outline of the tentacle arms and form a ‘Maltese cross’.

Seconds later, while I’m crouching to photograph his find, he tugs at my shoulder. “I’ve found another one.”

Junior finds another species, the Calvadosia campanulata, which gets its name from its bell-like shape.
Junior finds another species, the Calvadosia campanulata, which gets its name from its bell-like shape.

And so it goes on; Junior’s voice becoming more excited with every find. I can’t keep up. There are so many stalked jellyfish that Junior is finding three in the time it takes me to take a photo of one. They’re everywhere. As I’m taking the photos I keep finding yet more.

Two different species living together, Calvadosia cruxmelitensis (left) and Haliclystus octoradiatus (right)
Two different species living together, Calvadosia cruxmelitensis (left) and Haliclystus octoradiatus (right) at Portwrinkle

Now, I don’t like the cold. I may have mentioned that before? My hands, in particular, don’t cope well with being plunged into icy water or drying in an easterly wind. By the time Junior has racked up 26 stalked jellies and I’ve found a further 15, the pain in my fingers is becoming all-consuming.

Fortunately, by this time, the boys are more than ready to go to the pub for lunch.

“Have people actually looked for stalked jellyfish here before?” Junior asks as we head for the car.

“Yes, I think so,” I say.

“So it really is a proper world record?” he asks.

“Yes, I suppose so.”

Junior glances around him and narrows his eyes at a dog walker.

“What’s up?” I say.

“I don’t want lots of publicity. Do you think the newspapers and TV will find me? I’m not going to tell them where the stalked jellyfish are.”

I assure him that only people who care as much as we do about nature will ever read my blog.

He thinks about it for a moment and nods.

Despite the cold, I sneak in a few photos of other species. This is a baby sea hare (Aplysia punctata).
Despite the cold, I sneak in a few photos of other species. This is a baby sea hare (Aplysia punctata).
Decorator crab (Macropodia sp.)
Other Half found this fantastic Decorator crab (Macropodia sp.)
Painted top shell at Portwrinkle
Painted top shell at Portwrinkle

Tomorrow I’ll be off to the rock pools again, on the north coast this time, and I’ll be taking a day off from stalked jellyfish!

Junior and Senior doing our thing at Portwrinkle
Junior and Senior doing our thing at Portwrinkle

For everyone who loves Cornwall's rock pools. Information about great beaches, marine wildlife and conservation.