Scorpion fish eggs (Taurus bubalis), Hannafore

Spring arrives early in the rock pools

There’s no better way to explore the shore than with a group of experienced rock poolers. During this month’s big spring tides, I was privileged to join a small, dedicated team to survey Hannafore Beach in Looe. Best of all, David Fenwick who runs the brilliant Aphotomarine website brought along his newly-converted marine laboratory camper van for a test run.

A few weeks on and I’m still downing hot chocolate to recover from the cold (any excuse!), but this was a priceless opportunity to expand my knowledge and encounter new species. Over the week we recorded over 230 species, some of which I never knew existed and I finally found my first Snake pipefish.

Glamorous beach wear for the new season - me wearing every piece of clothing I own under my waders! Photo by Cornish Rock Pools Junior.
Glamorous beach wear for the new season – I’m wearing every piece of clothing I own under my waders! Photo by Cornish Rock Pools Junior.

Day one got off to an inauspicious start. David’s marine lab van broke down on its way to the beach, meaning he missed the best of the tide that day. Those of us who did make it had to leap back into our cars to take refuge from the hail before we’d even got our boots on.  Despite the wind chill, we were soon in full swing. Incredibly, the pools were full of signs of spring.

Scorpion fish lay their clusters of yellow glitter-ball shaped eggs earlier than most other species. In some, the baby fish were already taking shape and hundreds of eyes gazed into my camera lens.

Scorpion fish eggs with eyes looking out.
Scorpion fish eggs with eyes looking out.
A Scorpion fish (Taurus bubalis) - perhaps one of the proud parents - relying on camouflage not to be seen.
A Scorpion fish (Taurus bubalis) – perhaps one of the proud parents – relying on camouflage not to be seen.

Along the grooved bellies of some of the worm pipefish, there were also lines of eggs. Like seahorses, it is the male pipefish that carries the eggs until they hatch.

It’s hard to think of slugs as migratory animals, but several sea slug species have made their annual journey onto the shore to breed. We saw lots of the rarely-recorded slug Aeolidella alderi. My friend Jan from Coastwise North Devon found one that had been chomping on a dark anemone. The colour had passed into the cerrata on its back so that instead of the normal bright white, this one looked almost red.

Aeolidella alderi sea slug - with pigment in its cerrata, probably from eating an anemone.
Aeolidella alderi sea slug – with pigment in its cerrata, probably from eating an anemone.

Another had distinct yellow tips to its antenna and cerrata. This species always has a ring of short white cerrata below the head, making them look like they’re wearing a white ruff.

Another Aeolidella alderi - this time with yellow tips to its cerrata and antennae.
Another Aeolidella alderi – this time with yellow tips to its cerrata and antennae.
An unusual yellow Daisy anemone - perhaps what the sea slug had been eating.
An unusual yellow Daisy anemone – perhaps what the sea slug had been eating.

Nearby, a relative of Aeolidella alderi, the more common ‘Great grey sea slug’ (Aeolidia sp. probably filomenae) is feasting on an anemone. This hungry slug isn’t holding back and has dived headfirst into its feast.

Headfirst into its lunch - a Great grey sea slug (Aeolidia sp.) eating a snakelocks anemone.
Headfirst into its lunch – a Great grey sea slug (Aeolidia sp.) eating a snakelocks anemone.

Yellow-clubbed sea slugs (Limacia clavigera) were also out looking for mates. They’re not easy to spot when the tide’s out, as they look like minute splodges of white jelly on the rocks. Once in the water, they are transformed, with spiral rhinophores sprouting from their heads and robust yellow-tipped cerrata sticking out from their heads and bodies.

Limacia clavigera - the yellow-clubbed sea slug exploring my petri dish.
Limacia clavigera – the yellow-clubbed sea slug exploring my petri dish.

When, towards the end of day 2, I glimpsed a shape gliding through the seaweed my heart leapt. I’ve been looking out for this fish for years to no avail, but this one was hovering above my foot. Snake pipefish, like other pipefish, freezes and relies on its fabulous camouflage to escape predators.

Snake pipefish showing off its distinctive trumpet nose and pale striped pattern.
Snake pipefish showing off its distinctive trumpet nose and pale striped pattern.

I was able to reach into the water and lift it out for a quick photo. It wasn’t slippery to hold, but it wound its body around my arm so I had to overcome the powerful urge to squeal and drop it.

Snake pipefish can grow to 60cm and have pale vertical lines down their bodies so are easily recognised. They like to live among sea grass beds so are not commonly seen on the shore.

Snake pipefish (Entelurus aequoreus) on a brief visit to my bucket before release.
Snake pipefish (Entelurus aequoreus) on a brief visit to my bucket before release.

Inevitably, other fish were more evasive. David saw a Conger eel among the kelp, but it slipped away.

Among many amazing and less-common species, David Fenwick showed me this rare prawn, Caridion steveni, which appeared to have an especially short, blunt ‘nose’ (rostrum) compared to some other species. Its bright red pigmentation helps it blend in to the seaweeds.

Caridion steveni - A rare prawn species (Hippolytidae family)
Caridion steveni – A rare prawn species (Hippolytidae family)

Among the weeds on the rocks, tiny spider crabs were everywhere, only visible when they moved their spindly legs. Even when I take close-up photos it can be hard to make out the shape of the crabs.

A small spider crab - Macropodia deflexa (identified by its downcurving rostrum)
A small spider crab – Macropodia deflexa (identified by its downcurving rostrum)

Junior spotted a crab with an even more amazing disguise. We were looking under a boulder when he gasped and pointed at a seaweed-covered stone.

What I thought was a seaweed-covered stone.
What I thought was a seaweed-covered stone.

‘It’s a crab, I saw it move,’ he whispered, as though it might hear him and realise the game was up.

Whichever way I looked at the stone that Junior was waving his finger at, it still looked inanimate. It was only when I picked it up that I felt the sharp spines of the Common spider crab (Maja bracchydactyla) lurking below the seaweed camouflage. We turned it over to see the crab’s legs neatly tucked under its carapace. Junior delighted in placing the ‘stone’ back in the water to watch it sprout legs and scuttle away into the safety of the seaweed.

Even up close it was hard to tell this is a crab - but I could feel the sharp spines on its shell and the legs began to move.
Even up close it was hard to tell this is a crab – but I could feel the sharp spines on its shell and the legs began to move.

On day one I reached, or frankly surpassed, my cold tolerance limit. By the end of the week I  was only able to function by keeping my hands thrust deep inside my scarf to warm them against my neck. I must have ressembled a trussed chicken, but there was no point caring. As always, the rewards outstripped the pain.

Next weekend we’re expecting some huge spring tides in Cornwall, and yet more freezing winds, so you know where I’ll be.

I’m excited to be leading a couple of fabulous training events on Friday 2 March in Falmouth and Sunday 4 March in Looe. Maybe I’ll see you there? Wrap up warm!

Ophiocomia nigra brittle star
Ophiocomia nigra brittle star
Humpback scallop
Humpback scallop
Jewel anemones
Jewel anemones

8 thoughts on “Spring arrives early in the rock pools”

    1. Wow – what was your dissertation about? Snakelocks anemones are fascinating – lovely to look at and very variable in colour and where they attach. The Great grey sea slug retains the stinging cells in its cerrata as a defence I believe… it was great to see one mid-feast (not so great for the anemone of course!). I’ve also observed that the presence of snakelocks anemones growing on seaweed (instead of rock) is a good indicator that the area is likely to have Stalked jellyfish. Oh, and Snakelocks look amazing under a UV torch! Love them!

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      1. I was tutored by Dr Barbara Brown at Newcastle University, who was a specialist in bleaching of corals (in the early 1980s). I was looking at the effects of temperature stress on zooxanthellae expulsion from the anemones and looking for parallels in Carribbean corals. Can’t remember too much about it all if I am honest.

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  1. Great blog post Heather, I see you guys really did find a good selection of creatures. Does the 230 include seaweeds? Mobile lab – i want one. Thank you for getting so cold to bring these, we wimped out, we were coming your way for the big tides but it was so cold and wet we hunted slugs on our home patch instead not as much variety but we found a new gorge to hunt in. Enjoy the training days and see you at the shoresearch conference.

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    1. Thanks Mark. I can’t blame you for not coming down – the winds made conditions far from ideal and it was utterly freezing, but still good. Yes, the total includes seaweeds, although that wasn’t the main focus. Did you find many sea slugs in your trip? I kept finding the same ones at Hannafore – I had Rostanga rubra, Limacia clavigera, Aeolidella alderi, Aeolidia sp., Elysia viridis, Aplysia punctata, Goniodoris nodosa & Sea lemons plus various Lamellaria which don’t count but always confuse me! David had some more unusual ones from washing kelp holdfasts in the van – Junior very reasonably reached his limit after a few hours each day so I didn’t get to play in the van much as I’d have liked to! See you at conference… which conveniently is in my home village so will visit parents at the same time. Easy!

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  2. I have always wondered why there is a solitary record of Anemonia viridis on the east coast (around about Berwick rather than Newcastle) and it seems that Barbara Brown & Co. were shipping-up specimens from Cornwall. What happened to those anemones when the experiments were done?

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