Monday, 19 September 2016

Rockpool Excitement!

Somehow, rockpooling seems to have become quite a regular topic on the BioBlog! It is one of my favourite ways of looking for wildlife, as I love both the sea and the life forms which reside in it. Today, the subject is again rockpooling, this time with the Phoenix Group, which I have talked about several times before, here, here, and here. I did do rockpooling with the group once before, at Robin Hood's Bay, which can be seen in the third link, so this time I was hoping for a similarly great outing. As usual, Phoenix did not disappoint.

We travelled to the Flamborough coast for our rockpooling, and met up with Anthony Herd from the Living Seas Centre. I have met Anthony several times before, and he's a great guy, and very knowledgable on marine life. He regularly goes in search of aquatic creatures on this stretch of coastline, but even he was excited about today, as it was an unusually low tide, revealing the lower shore. Here the water would normally be quite deep, allowing kelp to grow, attracting a variety of life forms which you wouldn't find higher up on the shore. This unusually low tide allowed to explore this particularly biodiverse area which normally we would only be able to reach by diving down to it!

The weather was sunny and warm, and so we got straight to rockpooling, following the tide as it went out, exploring area by area as they were revealed. My first find was hidden under a rock: a group of tiny long-clawed porcelain crabs. I'm not sure why, but there's something that I find very endearing about this diminutive species. Its carapace grows to around 1 centimetre wide, and it has a different method of feeding from other crabs which you can find in British waters. It is a filter-feeder, rather than a scavenger, catching organic particles in the water column, then eating them. There is another species, the broad-clawed porcelain crab, which has a similar lifestyle, but I don't think that I need to explain the different between the 2 species!

After our porcelain crabs (which could be found under most rocks), our finds came thick and fast. I was pleased to find several small edible crabs, as I don't generally find these in Filey, which is where I usually go rockpooling. Next was a shore crab, then some breadcrumb sponge and star ascidians under the same rock, and then, the highlight of my day: what appeared to be a slender seaweed stem. Once Anthony put it in our white bucket, it quickly become clear that this was actually something that I've always wanted to see, a worm pipefish! These slender, eel-like fish are relatives of the seahorse, with tubular snouts with a small mouth at the end, used for sucking up food particles. Like seahorses, the male looks after the eggs, but in the pipefish's case, he doesn't keep the eggs in a pouch. Instead, they are stuck to a patch of soft skin on his underside in rows.

 See if you can spot the 3 worm pipefish in this picture!
By Gabrielle Ringot - Own work, CC BY-SA 4.0,

Not long after our find of the worm pipefish, shouts from a nearby group of rockpoolers attracted our attention. 2 girls had found a close relative of our specimen: a snake pipefish. This is an entirely different creature to the worm pipefish, as it is much longer, bears stripes down its side, and it has a dark marking running from its snout to its eye, and then along its head.

Next we found a small-ish common lobster, which began to flop rapidly through the rockpool when I tried to capture it. What I like to think of as 'flopping', is technically known by the less snappy name of the caridoid escape reaction, sometimes called lobstering or tail-flipping. This is the process of lashing out with the tail, forcing the creature backwards through the water. It is a method of movement used by shrimps and lobsters, usually only to escape danger. More information on the caridoid escape reaction can be found here.

Other crustacean species were discovored fairly quickly after that, including squat lobsters, hairy crabs, chameleon prawns, and the velvet swimming crab. The latter was revealed in large numbers as the tide went out. In fact, by the end of the day, I'd seen enough of the species to last me a lifetime! They are quite attractive crabs, with large olive to brown bodies, bluish or even purple claws, and bright red eyes. Their hind legs are flattened and beautifully marked with blue and black stripes, and rimmed with hairs. These are used for swimming, hence the name of the species. However, these crabs may be pretty to look at, but never have I encountered such an aggresive wild animal. Normally a crab may try to pinch you when you pick it up - yet the velvet swimming crab seemed to go out of its way to hurt you. Several times a crab would dart out from under a rock, nip me, then scurry back again. I started looking carefully around the rock for crabs before lifting it up, after several times having angered a crab. Non of this would have been so bad, if it wasn't for the shear number of them: there were literally hundreds of crabs. Non of my fingers ecaped the day unscathed by the pincers, and even my ankles were nipped several times.

Moving on from crustaceans, we also found several fish. Our first find was a 5-bearded rockling, a fish that rather resembles a catfish, and after that there were the pipefish, and a butterfish. We also found a few unidentified gobies in one particularly large rockpool.
I was expecting to find beadlet sea anemones, but I found not one. However, I did discover several dahlia anemones, a fairly large, dumpy species with short tentacles. They have a somewhat warty appearance, and are variable in colour: they can be pink, brown, reddish, or cream. The individuals that I found were a sort of brownish-red, but one had a yellowy sort of body with attractive red streaks on it.

I think out of everything, my favourite find was a rather unexpected one: a bloody Henry starfish. This name actually refers to 2 species, Henricia oculata and H. sanguinolenta, which are difficult to identify, so all that we can say is that the starfish that I found was one of the 2. I was very excited about my find, because this species is my favourite British starfish. It is bright pinkish red, with a maximum diameter of around 20 centimetres. Most other starfish that we could have found are active predators, the bloody Henry, on the other hand, feeds mostly on plankton and organic particles in the water column, occaisonally eating sponges and hydroids. According to this website, the species is only present on the south, west, and north coasts of Britain and Ireland - but we found our specimen in the east!

After a morning rockpooling, we ate our lunch and rested a bit, then carried on to Danes Dike. On the beach there we spent the afternoon doing a beach clean, collecting a large amount of plastic, but also rope, aluminium cans, fishing line, and strips of rubber from the underneath of lobster pots.

Overall, what a great day! We got to see some great marine wildlife, then help our native coastline by participating in a beach clean. Sounds like a day well spent to me.

Until next time, keep on the wild side!


  1. Hi Jacob, it's Harry from Phoenix, can you remember what the bryozoan was Anthony referred to as 'Sea Mat'? Great post by the way.

  2. Sorry, Harry, I'm afraid that I can't remember the species name.
    We should keep in touch by swapping emails. If you post yours in a comment, then only I will be able to see it because I can control which comments can be seen publicly.