Colours in the rock pools at Hannafore, Looe. Catshark eggcase encrusted with star ascidian, keel worms, seaweeds, etc.

Dolphins and discoveries

There’s no more auspicious start to an afternoon’s rock pooling than a dolphin display while you’re munching your pasty.

Jan from Coastwise North Devon, Junior and I were treated to an incredible leaping, spinning pod of dolphins at the start of our last Looe rockpooling foray, which could only be a good sign.

We were far too busy watching the dolphins to take any good photos - but some distant fins here just to prove there really were dolphins.
I was too busy watching the dolphins to take any good photos, but here are some distant fins.

Following a busy summer season, it was magical to have the beach to ourselves. Despite a keen wind that made it difficult to see into the more exposed pools, the sheltered gullies were full of colour.

Every colour variant of the beadlet anemone was on display in one short stretch of pools. These common anemones are often red, but here they showed off their full traffic-light range of shades. Some splayed open a shower of bright tentacles, while others were retracted, showing nothing but the distinctive blue circle at the base of their columns.

A rather green beadlet anemone with blue markings around its base and on its mouth.
A rather green beadlet anemone with blue markings around its base and on its mouth.
A closed-up orange beadlet anemone
A closed-up orange beadlet anemone

Junior’s sharp young eyes were focused on the task and he brought us several isopods to identify. These minute woodlouse-type creatures swam around our pot-lids at high speed while we tried to photograph their tails. All of them had two prongs on their backs, so were male Dynamene bidentata.

One of Junior's isopods - a Dynamene bidentata
One of Junior’s isopods – a Dynamene bidentata

We used our cameras to focus in on the blob-like bodies of the Ascidia mentula sea squirts, which we found attached to several rocks. From a distance, they have a pink tinge. Close-up, they seem to be gearing up for fireworks night, with bursting patterns of red sparks along their sides.

Pink fireworks - patterning on an Ascidia mentula sea squirt.
Pink fireworks – patterning on an Ascidia mentula sea squirt.

Lurking inside the sediment-filled layers of a fractured rock, was a colony of Thalassema thalassema spoon worms. These wonderfully alien creatures have plump pink bodies like an overfed grubs, with an extendible, frilled proboscis.

One of many contenders for the 'strangest animal in the rock pools' award - the echurian worm Thalassema thalassema
One of many contenders for the ‘strangest animal in the rock pools’ award – the echiuran worm Thalassema thalassema

Unlike many other marine worms that speed around on bristly legs or swim with paddles, Thalassema thalassema seems to have no efficient means of locomotion.  Instead, it rolls contentedly in the muddy sand, feeding on detritus.

These worms alarm me with their indolence. I always suspect that, like most vulnerable-seeming marine animals, they must have some secret defence. Many worms have a impressive set of biting jaws, but despite my wariness this species is safe to handle. I think.

Among the dense carpet of animal colonies, among them sponges, sea squirts, bryozoans and hydroids, we found a smart small species of spider crab, probably Macropodia sp. It was perfectly camouflaged to hide among the seaweeds.

A perfectly decorated small spider crab (Macropodia sp.) at Hannafore
A perfectly decorated small spider crab (Macropodia sp.) at Hannafore

Further out in the lagoon, near a seagrass bed, we found several egg cases of the greater spotted catshark, Scyliorhinus stellaris. In some we could see the fresh yolk, in others the baby was forming while some were already hatched and thickly encrusted with life.

A fresh Greater spotted catshark (Scyliorhinus stellaris) egg case showing the yolk.
A fresh Greater spotted catshark (Scyliorhinus stellaris) egg case showing the yolk.

By the time we reached the rocky outcrop at the far side of the lagoon, the tide was at its lowest and we could only stay a few minutes.

Inevitably, the finds rolled in just as the tide was turning. Junior was delighted with the yellow colour of this common brittle star, Ophiothrix fragilis, which is more usually pink in colour when we see it further up the shore.

Junior's yellow brittle star
Junior’s yellow brittle star

Under one stone was a faint lattice pattern marking the spot where, earlier in the season, a clutch of clingfish eggs had been attached. Although they seemed to be long-since hatched, the site was still being watched by what was probably an anxious parent.

Cornish clingfish - Lepadogaster purpurea, Looe.
Cornish clingfish – Lepadogaster purpurea, Looe.

A speck of blue on the rock concealed a good cause for any clingfish parent to be concerned: a Calma glaucoides sea slug. Despite the elegance of its long blue cerrata, flashing their golden tips as they waved in the water, this slug could well have destroyed the entire brood of eggs, which are its food.

Calma glaucoides - a sea slug (nudibranch) that feeds on clingfish eggs.
Calma glaucoides – a sea slug (nudibranch) that feeds on clingfish eggs.

We could easily have knelt around the pool for longer, wondering at this tiny creature, but a change in the wind and a stirring of the kelp out towards the island meant that the race was on.

We sploshed and slid our way back over hidden rocks and through tangled weed that grabbed at our ankles, watching the flow of water growing by the second as the powerful tide raced in. Behind us, the water was working fast to submerge the slugs, shark eggs, anemones and brittle stars, closing the door on the watery world.

We made it back without over-topping our wellies; wishing, as always, that there was a little more time between the tides.

On the way to the shore we found this vivid green prawn with a huge left claw - at first we thought it might be a snapping prawn, but it turned out to be an unusual colour variant of the more familiar hooded shrimp.
On the way off the beachwe found this vivid green prawn with a huge left claw – an unusual colour variant of the more familiar hooded shrimp.

 

2 thoughts on “Dolphins and discoveries”

  1. If only the tide would give us a few extra hours or even better go just that bit down the beach. I wonder how many of us have said that as we find that gem of a creature we can’t quite get a pic of just as the waves cover it back up. Great blog Heather.

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    1. Thanks Mark. I think it’s mostly it’s a good thing that humans can’t access the marine world too easily as I’m sure it wouldn’t remain rich and diverse for long if we could.. but I always find the best things when the tide’s just turned and I have to leave!

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