Aquarium Update 14: anemones

A short update on the aquarium; I have collected some more anemones and hope to collect a lot more now spring has started (I went for my first dive of the year this Friday; it was really nice to be back in the water but the visibility was really bad and it was only 9 degrees!). I do not have a decent full tank shot (FTS as it is called on aquarium fora…) but decided to post some quick iPhone pics anyway. The first photo shows three species: top left is a Diadumene cincta or lineata, bottom left a Dahlia anemone Urticina felina and the two on the right are Strawberry anemones Actinia fragacea. Next a Plumose anemone Metridium senile followed by a white variety of the Red-speckled anemone Anthopleura ballii. I feed the anemones a couple of times a week by hand with pieces of defrosted shrimp. The anemones readily take up the shrimp, especially the Dahlia anemone is very quick to grab food and close up. The Plumose anemones are more difficult as they are often closed (they slowly open up when they sense food in the water but often they don’t) and have very fine tentacles not suited to feeding on larger particles. They would be better fed with zooplankton from a turkey baster but I have been too lazy to do that. When they are fully extended they are beautiful, white or orange but often they are flat as a pancake and shift shape a bit, leaving behind pieces of tissue that sometimes develop into tiny anemones. I have some beadlet anemones and a small orange and white species I am not sure of too. There are a whole bunch of other species (I can recommend this excellent guide) and many are very beautiful (see here for a gallery of photos by Paul Kay). The plan is to try to find more Dahlia anemones, as these come in many colour variations, but they are not very common in the rock pools here. A common species when snorkelling in the Helford is the Mud sagartia, which would also be nice to have. I am doubting about getting some Snakelocks again: they are very pretty and I could get the commensal spider crab as well, but they are also quite deadlyIMG_2436 IMG_2191IMG_2165

a weird mollusc in Mylor Marina

In the series ‘pontooning‘, I returned to Mylor a week ago Friday to have a quick look around in the marina. The water was choppy, but visibility on the sheltered side of the pontoons was OK. I noticed a brown slug-like thing flapping about next to a boat. My first thought was a sea hare (I have seen plenty but have not yet seen them swimming). Upon closer inspection, I saw that it was something else, it had a shell like Haminoea or Akera, species I had never seen, especially not swimming. It turns out that it was Akera bullata, an Ophistobranch mollusc that is rarely seen in Cornwall and generally is observed crawling on the mud, not swimming. Why they swim is not well understood, but they usually swarm in numbers and so there must be some general response to the environment or mating behaviour going on. I saw four other individuals nearby so that fits. I made a couple of movies but as I could not look through the viewfinder the footage is not great (I went back Saturday and Sunday to try and find them back but was not able to). The shell can be clearly seen hanging down (Akera is related to the Sea hare but has retained its external shell). When lifted out of the water, the animal folds its mantle around its shell.

IMG_9973There were some other interesting things to see. The dominant organism on the pontoons is the tunicate Cione intestinalis (I see there are some other tunicate species hiding in these pictures; I will have to take a closer look next time). Amongst it grows the purple invasive Bryozoan Bugula neritina. Next, a colonial tunicate thta could be Botrylloides violaceus, Trididemnum cereum or Didemnun maculosum (or something else again). After that, the beautiful Lightbulb sea squirt Clavelina lepadiformis.IMG_1849IMG_1656IMG_1677IMG_1704Plumose anemones Metridium senile are always common here. I for the first time noticed another species Diadumene cincta, very pretty! IMG_1867IMG_1859 IMG_1754 IMG_1745