tunicate time

Posted on August 22, 2013 by An Bollenessor under rock pooling, tunicates

After being abroad a couple of times this summer (Slovenia, France 1 2 3 and The Netherlands), I have started rock pooling in Falmouth and Flushing again. Things have noticeably changed since the spring, most prominent being the recent abundance of all kinds of sea squirts (tunicates). They are everywhere, and some of them I have not seen before. The solitary sea squirt Corella eumyota is very common, with smaller individuals a translucent white and larger individuals more orange:

My personal favourites the colonial Botryllus (in the above picture bottom left among the bryozoans) and Botrylloides are also very abundant at the moment. I should measure the width of a population on a recognizable, large rock and go back to check how fast they grow actually. Below a picture of both species growing side by side:

Some more Botryllus schlosseri pictures demonstrating the variability in colour (the Botrylloides leachi here look all the same):

A species that I had not noticed before and is growing in every rock pool in Flushing at the moment is the orange Morchellium argum, which grows as a colony as does Botryllus or Botrylloides but in a rather different way. A colony consists of a stalked club with individual zooids protruding from the ‘head’:

Mud pooling

Posted on May 8, 2013 by An Bollenessor under anemones, crustaceans, eggs, fish, molluscs, rock pooling, sponges

When it was very low tide last week, I decided to skip the ‘rock pools proper’ on my local beach in Flushing and to check out the zone just below where the rocks and the sandy bottom of Penryn River (an arm of the Fall Estuary) meet. All common rock pool inhabitants – winkles, top shells, edible crabs, worm pipefish and shannies – still live here, but some other organisms are more abundant here than in the rock pools.

Sponges are very common in this silty environment, especially the Estuary sponge Hymeniacidon perleve:

The Breadcrumb sponge Halichondria panicea:

In addition to sponges, I noticed quite a lot of the colony-forming ascidian Botrylloides leachi (see previous post). That explains why I could also find a couple of European cowries Trivia monacha, their predator. Also very common here are the Variegated scallop Chlamys varia and the Thicklipped dog whelk Hinia incrassata (top right picture). I am not sure what the slimy beige stuff is!

I spotted a couple of new things as well, the Red speckled anemone Anthopleura ballii:

Also a first, a Sea spider Nymphon (gracile?):

I found a large patch of these beautiful eggs:

and someone guarding them, a rock goby Gobius paganellus:

A Butterfish Pholis gunnellus:

Very common were little Squat lobsters Galathea squamifera (no picture), rapidly swimming backwards to escape. Even more abundant were these little Hooded prawns Athanas nitescens:

Botrylloides leachi

Posted on May 6, 2013 by An Bollenessor under tunicates

One of the most beautiful organisms growing on the rocky shore: the colonial ascidian Botrylloides leachi (it does not have a common name). This is a type of Tunicate. The colony is embedded in a gelatinous but hard test, which is unusual to the touch. The test contains strings of individual tunicates (zooids); you can see each has a siphon on the top, water enters here, and is filtered by a mucus-net that is eaten along with the filtered microbes. Filtered water exits from a shared siphon in the middle of the colony. I am not sure what the yellow ‘stiles’ are, but suspect that they are budding zoids. In the related species Botryllus schlosseri (I will post some pictures of this species in another post), a model system for research, each zoid is resorbed in the test and replaced by a newly bud zoid on a weekly basis.

P.S. In hindsight, this might be B. violaceus (see here)

rock pooling from the comfort of my home

Posted on March 27, 2013 by An Bollenessor under anemones, bryozoans, crustaceans, eggs, molluscs, rock pooling, seaweeds, tunicates

It was too cold and windy to spend a lot of time on the beach, so I took a closer look at my seaweed catch back home. I was amazed at the diversity of organisms growing amidst the weeds. A lot of them are easily overlooked when rock pooling as you need some time (and preferably a comfortable seat) to find them. Below Bushy rainbow wrack with epiphytic False eyelash weed and Pink plates Mesophyllum lichenoides (I will not give the Latin names of species described in preceding posts for brevity). Some bright green sea lettuce Ulva, a grey topshell Gibbula cineraria, a snakelocks anemone Anemonia viridis and in the middle a bright orange colony of the tunicate Botrylloides leachi: I found many large Breadcrumb sponges Halichondria panicea but the picture I took did not turn out to be in focus. I do not know what the organism below is, perhaps a bryozoan (please feel free to comment!). I am not sure what this is either! Dog whelk Nucella lapillus eggs (I now also notice a tiny brittle star in the middle): Egg cases of the thick-lipped dog whelk Hinia incrassata: A small snakelocks anemone; interestingly enough all of these were the green variant (with purple tips) and there were none of the pinkish ones. I have read some interesting notes about aggressive behaviors between the two types, something to look into for a future post. A Marbled Crenella Modiolarca tumida, a tiny bivalve typical of seaweed holdfasts: A tiny White tortoiseshell limpet Tectura virginea: I saw something creeping out of the seaweeds on the floor out of the corner of my eye: a small Long-legged spider crab Macropodia rostrata. This species adorns itself with seaweeds for camouflage: