Category Archives: Fish

Giants of the Cornish rock pools

Last week I shared with you the miniature world of the sea slugs, so this week I’ll super-size things and bring you some big fish. Silly-season reports of Great-white sharks often hit the headlines in Cornwall, but I prefer rock-pool giants; they’re not made up, and you can get close to them without having your leg bitten off!

Cornwall is brilliant in all sorts of ways, our network of local, grassroots marine conservation groups being just one of them. The public launch, last week, of the new Three Bays Wildlife Group brought experts and volunteers together and gave me a chance to explore some new beaches in the St Austell area.

Judging by the squeals of excitement from the children and adults alike, the crabs, pipefish, prawns and anemones we found at the main rockpool ramble on Portmellon beach near Mevagissey went down well. By the end of the day, the local group had recruited lots of potential new volunteers.

Green shore urchin at Portmellon beach - adorned in seaweed
Green shore urchin adorned in seaweed. Portmellon beach.

At the end of an event I’d usually relax and enjoy my sandwiches, but the group was keen to survey another local beach. The walk to Colona was like something out of an Enid Blyton adventure. Cresting the hill out of Portmellon, we passed a disused cattle grid filled with nettles, beyond which the view opened out to sheep-grazed pasture plunging down to the bay. The whitewashed house on Chapel Point, to the east of the beach, perches over azure waters and would be any rockpooler’s dream pad.

Walking down to Colona bay
Skipping down to Colona bay

Matt Slater from Cornwall Wildlife Trust was straight out on the rocks setting fish traps in the deep pools. Matt, of course, is a fully-licensed professional giant catcher.

After just half an hour of mooching about the pools looking at anemones and some fine lugworms, we clambered across to check the traps. The first looked successful. At the back of the yellow-mesh cage, several creatures wriggled while Matt hoisted them onto the rocks and eased them into an awaiting bucket.

Once the greedy shore crabs that had been feasting on fish-bait had been picked out, there were three fish left. Every one of them was large by goby standards. One in particular was what Junior would describe as “a whopper”. Matt’s face said it all. From the fishes’ fleshy lips that could out-pout Mick Jagger to the beady eyes, it was clear that all three were Giant gobies (Gobius cobitus).

Three giant gobies from the first trap.
Three Giant gobies from the first trap.

These fish have special protection under the Wildlife and Countryside Act and are at the northernmost point of their range around south west England. They’re not well recorded because they’re elusive and can be mistaken for the much more common Rock goby.

Giant gobies have huge lips, small eyes and lack the yellow band at the top of their first dorsal fin (distinguishing them from the Rock goby)
Giant gobies have huge lips, small eyes and lack the yellow band at the top of their first dorsal fin (distinguishing them from the Rock goby)
Another feature of the Giant goby is the fleshy lobe on their adapted pelvic fin - this helps them to sucker onto rocks
Another feature of the Giant goby is the fleshy lobe on their adapted ventral fin – this helps them to sucker onto rocks

To round off our week of giants, Junior and I took a stroll around a sheltered lagoon in Looe, after a Fox Club event and came across a fish even larger than a Giant goby. In fact, I was so busy examining tiny hydroids on seaweed looking for sea slugs that I practically tripped over the young catshark.

Greater spotted cat shark (Scyliorhinus stellaris) in a Cornish rock pool, Looe
Greater spotted cat shark (Scyliorhinus stellaris) in a Cornish rock pool, Looe

The Greater-spotted catshark goes by many different names (bull huss, nursehound, dogfish, etc.) and is far larger than a Giant goby, growing to around one and a half metres long when mature. The one I nearly stepped on in my neoprene beach shoes was just a baby, but still an impressive fish.

Catsharks tend to lie still for camouflage, so they’re easily approached to take photographs. If you touch one, as Junior did at the first opportunity, you’ll also notice that their skin is like sandpaper. Rough sharkskin is remarkably hydrodynamic, so much so that engineers are looking at ways to copy its structure to make swimmers faster and ships more fuel efficient, among other things.

This close-up of the catshark's skin shows how rough it is. You can also see the dark and white spots that are characteristic of this species.
This close-up of the catshark’s skin shows how rough it is. You can also see the dark and white spots that are characteristic of this species.

I think Junior would like it even better if we could stumble across a giant squid circling the pools, but for now, a shark will certainly do. The giants of the Cornish rock pools aren’t as easy to spot as you might imagine, but it’s well worth the effort.

 

 

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Wrasse and wrack

The Cornish summers are anything but predictable. One day I’m sweltering in shorts and beach shoes and the next I’m shivering in waders and a thick jumper. Although the showers are back with a vengeance, there’s always something to be found if I can make it across the rocks without breaking an ankle.

Painted top shell, East Looe
Painted top shell, East Looe

My first outing is to the rocks beyond East Looe beach and I’m pleased to come across a new colony of St Piran’s hermit crabs on the mid-shore.

A St Piran's hermit crab starting to emerge from its shell.
A St Piran’s hermit crab starting to emerge from its shell.

They’re becoming a familiar sight around Cornwall and I’m starting to recognise them from the tips of their red legs, before their chequerboard eyes and equal-sized claws emerge from their shells.

St Piran's hermit crab showing its distinctive red legs and chequerboard eyes
A St Piran’s hermit crab showing its distinctive red legs and chequerboard eyes
This hairy crab was also out an about enjoying the showers.
This hairy crab is also out and about enjoying the showers.

Dragging the family with me on my next expedition, I take a look at the other side of Looe.

Junior and Other-Half exploring Hannafore in the rain
Junior and Other-Half exploring Hannafore in the rain

At Hannafore, the rocks are hidden under a thick brown  tangle of wracks, sargassum weed, and kelp making my feet slither with every step. It’s hard to make out where the pools are much of the time, let alone what’s in them.

Low tide at Hannafore, West Looe
Low tide at Hannafore, West Looe

Still, with some patience and careful sweeping aside of the long strands of weed, some treasures are revealed. This heart-shaped daisy anemone is the pinkest one I’ve ever seen.

An unusually pink daisy anemone
An unusually pink daisy anemone

As we wade in a long, deep pool a large fish passes between the fronds of sargassum near my feet. Moving slowly, I herd it towards a shallow corner, and, holding a bucket behind it take one more step. Nine times out of ten, I fail and the fish darts away never to be seen again. This time, the colourful fish takes me by surprise and swims straight into the bucket.

Junior getting to know our wrasse-friend
Junior getting to know our wrasse-friend

Here it is – is the first adult corkwing wrasse I’ve found in a rock pool.

Male corkwing wrasse have beautiful markings - they look almost tropical
Male corkwing wrasse have beautiful markings – they look almost tropical

Cornish Rock Pools junior comes over to admire the fish, talks to it and gives it a stroke. We look at its pouting lips and the iridescent blue stripes on its cheek, the typical colouring of the male corkwing wrasse. The female is much more dowdy.

After a few minutes, Junior lowers the bucket into the drizzle-spattered pool and we watch the wrasse swim free among the weeds.

I can see why most people see rockpooling as a fair-weather activity, but I’ve always liked the heavy calm of an empty beach on a foggy, damp day, and the animals are as colourful as ever.

Happy rockpooling!

Dahlia anemone, Hannafore
Dahlia anemone, Hannafore

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.

Summer Lazing in Cornwall’s Rock Pools

It’s funny how the summer days float by. The house has been practically bursting with people for weeks now and I haven’t found the space to write about our many beach trips, but August still feels like a lazy month.

It reminds me of my childhood summers; a jumble of paddling, swimming, rockpooling and finds. Only I’ve just turned 40 and now I’m the one remembering hats and towels, preparing picnics and being called on constantly to help build dams or identify creatures. Every few days I realise that I’ve failed to take many photos and still haven’t blogged anything I’ve found. It’s just the way August goes.

Compass jellyfish. Also known as sea nettles as they pack quite a little sting, these jellyfish have beautiful markings.
Compass jellyfish. Also known as sea nettles as they pack quite a little sting, these jellyfish have beautiful markings.

The warm waters are drawing in all sorts of creatures at the moment. The north coast especially is teeming with jellyfish. Harmless Moon jellyfish have washed up in their thousands. These transparent little jellies have four mauve circles in their centre in a pattern that reminds me of cucumber slices (OK, that’s probably just me). 

One of many moon jellyfish washed up by the strong swell. This species is harmless.
One of many moon jellyfish washed up by the strong swell. This species is harmless.

Other jellyfish that have mild stings, like the compass jellyfish are also washing in and I think my thigh met with one of the many blue jellies in the water at Mawgan Porth a couple of weeks ago from the unattractive rash I developed! On the plus side, some friends found a spiny starfish in a pool at the top of the mid-shore pools, which looked like it might be feeding on the stranded jellies. Continue reading Summer Lazing in Cornwall’s Rock Pools

Fun and fish at the Lundy Bay Bioblitz

Bioblitzes have become a regular thing these last few years and I love them. These time-limited surveys of every living thing in an area are a fantastic way to bring experts and the public together, so I’m excited to join the Lundy Bay 24 hour bioblitz organised by the National Trust.

Getting started on the beach with at the Lundy Bay bioblitz
Getting started on the beach with at the Lundy Bay bioblitz

When I first walk down on the first afternoon to do a pre-survey recce there’s no beach at all. The tide is high and the waves are exploding against the rocks sending up a shower of spray that delights Cornish Rock Pools Junior. Fortunately, some intrepid friends from the Marine Biological Association and Coastwise North Devon arrived early and collected a lovely hydroid medusa (like a tiny jellyfish) and lots of moon jellies – so it seems likely there will be interesting things to find when the tide goes back out.

One of many moon jellyfish washed up by the strong swell. This species is harmless.
One of many moon jellyfish washed up by the strong swell. This species is harmless.

After an exciting evening and early morning of mammal surveying with Junior, I finally get to see the beach at low tide. It’s an exposed shore with sheer rocks and golden sand, which looks wonderful, but is a tricky environment to find creatures. Still, with the number of people we have taking part and the combined resources of lots of different organisations including kick nets and fish traps, we’re sure to find something.

I spend most my time near the event flags, helping people to identify their finds. Everyone is fascinated by the sea hare. These common sea slugs are easily recognised by the long tentacle ‘ears’ on their heads. Up close, you can see a leopard-like pattern on their bodies. If you upset them (which we don’t) they can squirt out purple ink to confuse predators.

A small sea hare explores my tray.
A small sea hare explores my tray.

The find of the day is a creature none of us expect to find tangled in a discarded fishing net. This slow worm (a legless lizard) probably came down to the beach to hunt at low tide and became caught in the ghost net. It has a lucky escape and is released safely.

This slow worm was found tangled in discarded fishing gear.
This slow worm was found tangled in discarded fishing gear.

The nets bring up lots of tiny baby flatfish that were hiding in the sand in the shallows. Most are probably plaice and this one looks like a baby turbot – with a much wider body-shape. I’ve never seen one this small before, it swims onto my hand and rests there, looking around with bulging eyes, opening its lop-sided mouth a little. If it makes it to adulthood it may eventually weigh 10 kilos or more, but it has a way to go yet.

A tiny young turbot swims into my hand.
A tiny young turbot swims into my hand.

 Everyone loves a cheeky tompot blenny. There bold fish are unmistakeable with their fat lips, colourful eyes and television aerial style tentacles on their heads.

A tompot blenny giving its typical toothy smile.
A tompot blenny giving its typical toothy smile.

Other highlights include toothed crabs (Primela denticulate), celtic sea slugs, which are present in huge numbers on some large rocks around the point, and a lobster lurking at the back of a deep overhang cave.

Built like miniature tanks, the Celtic sea slugs cover the rocks in places.
Built like miniature tanks, the Celtic sea slugs cover the rocks in places.

After the strong winds and rain of the previous day, the sunshine takes us by surprise. Conditions are perfect and the turnout is good, but before long the tide is racing back in. By the time we make it back to base, the short, intense Bioblitz is coming to an end and the stands are being packed away. Soon this will be a remote empty field again, but I’ll be back sometime soon to explore this wonderful bay some more.

If you would like to join a Bioblitz there’s another one coming up in North Devon on 17th September at Croyde with the fabulous Coastwise North Devon team – see http://www.coastwisenorthdevon.org.uk/news/summerbioblitz-time.html

Kynance Cove: A rock pooling challenge

There are many fabulous rock pooling beaches around Cornwall and this isn’t one of them. The smooth serpentinite rocks of Kynance Cove on the Lizard peninsula are colourful and create breathtaking scenery, but they’re mostly devoid of places for creatures to shelter. Realistically there’s not much here, but it’s one of Cornwall’s loveliest places and experience tells me there’s always something if I look hard enough.

It's easy to see the snake-skin texture that gives serpentine rock its name.
It’s easy to see the snakeskin texture that gives serpentine rock its name.

One thing this beach does have is caves. Junior strides ahead of me, clutching a geological hammer and chisel, shining his torch along the smooth, damp walls.

Cornish rock pools junior explores the serpentinite caves
Cornish rock pools junior explores the serpentinite caves

He’s on a mission to explore every centimetre of these rare rocks, forced up millions of years ago from deep under the oceans, exposing the upper layer of Earth’s mantle. While Junior hammers away at history, cave-dwelling periwinkles not much bigger than grape pips are undertaking their own explorations.

This tiny periwinkle species lives on the upper shore in dark and damp places such as this cave.
This tiny periwinkle species lives on the upper shore in dark and damp places such as this cave.

A steady swell breaks against the island stacks and scattered rocks of the bay. Barnacles cling to imperfections and overhangs, joined by beadlet anemones and black-footed limpets.

A beadlet anemone next to dog whelk eggs. Barnacles and limpets also cling on to this small overhang in the smooth serpentinite.
A beadlet anemone next to dog whelk eggs. Barnacles and limpets also cling on to this small overhang in the smooth serpentinite.

I watch a limpet slamming down its shell on a barnacle’s feeding arms and wonder if it’s if it’s after a more substantial meal than its usual fare of micro-algae?

Sea slaters scuttle among the barnacles together with occasional flies and even a centipede. I assume it has journeyed down from the top of the grassy island to forage at low tide.

A centipede visiting the shore
A centipede visiting the shore

An oystercatcher watches me cross the beach, preening itself with its orange chopstick bill. It watches as I climb a shelving part of the lower cliffs where several deep bowls have been eroded from the rock.

A lone oystercatcher on a rock at Kynance Cove.
A lone oystercatcher on a rock at Kynance Cove.

As I approach the pools, a gaggle of small fish jostles against each other before darting away below a ledge. I take up position beside the pool and wait. Sure enough, after a few minutes, a shanny’s head pops over the ledge, propping itself on its clawed pectoral fins to get a better look. Others soon join it as they return to their basking positions at the shallow edges of the pool.

A grinning shanny propped on its pectoral fins watches me from a rock pool.
‘Say cheese!’ A grinning shanny propped on its pectoral fins watches me from a rock pool.

I lower my camera bit by bit until it’s almost touching the surface of the water. The fearless shanny stays put. After a few attempts I manage to capture one of my favourite things about these common little rockpool fish: their extraordinary chameleon-like eyes which can swivel independently in all directions.

Being able to do this must be a huge advantage when looking out for prey and predators.

I spot a Montagu’s blenny in the pool, easily distinguished from its larger cousins by its radio mast style headgear. It’s too shy to have its photo taken and I’m called away to help with  Junior’s mining exploits, but it’s been a rewarding morning. It shows how much is there if you look.

Barnacles on a beautiful piece of banded serpentinite.
Barnacles on a beautiful piece of banded serpentinite.

Hatchlings in the rock pools at Port Nadler

A sunny bank holiday weekend followed by a sunny half-term week is nothing short of a miracle. That the second weekend also coincided with some big spring tides is more amazing still.

I’ve seen some wonderful photos this week of rockpooling finds all around Cornwall. Some fabulous creatures. And if you haven’t been able to explore the shore yourself, Springwatch tonight (8th June) are going to be showing footage of the remarkable comeback of the Clybanarius ethryropus (nope, still can’t pronounce it) hermit crab, filmed with Cornwall Wildlife Trust at Castle Beach, Falmouth.

The stars of my pretty perfect day of wading through pools in the blazing sunshine at Port Nadler, near Looe, were the baby fish.

There are plenty of young fish around at the moment but the new hatchlings can hard to spot. I took this photo of clingfish eggs to capture the eyes staring out of each eggs and the little spotty tails curled round them.

Clingfish eggs hatching in a Cornish rock pool.
Clingfish eggs hatching in a Cornish rock pool.

It was only when I uploaded photo to my laptop that I realised I’d managed to capture my first hatchling (in the centre of the picture). I can’t get enough of those golden eyes.

A recently hatched Cornish clingfish among its egg-bound siblings
A recently hatched Cornish clingfish among its egg-bound siblings

Fish often stick around to guard their eggs and sure enough there was a proud parent next to this rock.

An adult Cornish clingfish showing the typical beaky nose, antenna by the eyes and blue patches on the head.
An adult Cornish clingfish showing the typical beaky nose, antenna by the eyes and blue patches on the head.

I was up to my waist between rocks leading to the open sea when I saw this pale creature, about 4cm long, wriggling amongst the darker kelp. From its elongated, looping form I expected a worm.

A recently-hatched Greater pipefish baby.
A recently-hatched Greater pipefish baby.

On closer inspection the large eyes and fins were clear. This is the first time I’ve ever seen a baby pipefish.

A baby Greater pipefish with yolk sac still attached. The large eyes and long snout are reminiscent of its cousins, the seahorses.
A baby Greater pipefish with yolk sac still attached. The large eyes and long snout are reminiscent of its cousins, the seahorses.

Judging by the yolk sac still attached to its belly, this little fish hatched very recently. I saw several more in the water, their curling movements reminding me of their cousins the seahorses. I wondered if the dad was close by – like seahorses, the male pipefish looks after the gestating eggs in his pouch until they hatch – but he’d be too well camouflaged to spot in this seaweed.

 The rocks were crawling with crabs and the pools were busy with the fry of larger fish that use these sheltered waters as nurseries. My camera battery was low, but this Limacia clavigera sea slug was worth draining my battery for.

A Limacia clavigera sea slug on the move.
A Limacia clavigera sea slug on the move.

 The water was so warm after a week of sun that I put on my snorkel for the first time this year and enjoyed a leisurely float across the bay, watching wrasse skirting the rocks and snakelocks anemones waving in the current. 

If this weather carries on, I can see myself returning to Port Nadler regularly this summer to watch the baby fish growing up.

Cornish Rock Pools junior drying off in the sunshine at Port Nadler, near Looe.
Cornish Rock Pools junior drying off in the sunshine at Port Nadler, near Looe.