Category Archives: beach combing

Monster in a Barrel

Posted on by under beach combing, crustaceans, Macro, tunicates

Last Sunday we made the trek to Sennen Cove beach in the far west of Cornwall. I have not been in the water for weeks due to the windy weather (and it might be a few weeks before conditions improve), so the only way to get my fix is by going beach combing… With strong westerlies, this spot jutting out into the Atlantic seemed a safe bet, although when we arrived the strandline appeared quite sparse and I did not have hope of finding much. A single find by my eagle-eyed son however made the trip all worth it!

The photos above show the amphipod Phronima sedentaria inside its home, a hollowed-out salp. These small crustaceans use their claws to carve a home out of their barrel-shaped gelatinous host. This offers protection, and a space to rear their young. They occur worldwide in the open sea and are believed to vertically migrate from depths up to a kilometer to the surface each night. Although it was still actively wriggling about, it was essentially doomed after being washed up, so it was taken back in a margarine container filled with seawater and handed over to David Fenwick (www.aphotomarine.com) for further examination. He made some excellent photos of it, making clear why it provided inspiration for the ‘Alien’ movie! As I suspected from the size, this was a female, and brood was found in the salp tunic as well.

These things have been found before a few times in the UK (in Sennen and in the Scillies) but not commonly (4 records on the NBN Atlas and 0 on iNaturalist). I have recorded mine on the latter database (which means it can make its way to NBN as well). Let’s see what else the sea throws up this winter!

Violet Sea Snail

Posted on by under beach combing, molluscs

An hour of beach combing today at Praa Sands, chosen because it is a reasonably long beach facing the prevailing wind that day. A fair amount of Goose Barnacles smattered among the rocks. On the strand line, bits of seaweed and lots of plastic rope fragments from fishing boats (which were duly picked up). Not expecting anything spectacular, my eye was caught by a tiny bit of violet, which proved to be a Violet Sea Snail! We had only found a Janthina janthina once before in our ten years in Cornwall but that was an empty shell whereas this still had its bubble raft. Janthina floats at the surface on the open ocean under this raft and therefore is part of the ‘neuston’ (or ‘pleuston’). It is a predator of other such purple ocean surface dwellers such as By-The-Wind Sailors Velella velella, and the Portuguese Man o’ War, Physalia physalis. It was tiny, the shell measuring only a centimeter or so. There were many By-The-Wind Sailors too, and these were just as small or smaller (usually they are 4-8 centimeters or so). I did not use a flash (looks to artificial), keeping ISO at 200 and f/7.1 I had to go down to 1/30s for shutter speed which was doable leaning on the beach. The protoconch is nice and sharp when you zoom in.

Necklace Shell

Posted on by under beach combing, iPhone, molluscs

A quick post as it has been a while…..Last Sunday we went on a walk on sunny Carne Beach on the Roseland Peninsula. The primary aim was to get some fresh air, the second to find some dahlia anemones to bring home to the aquarium (we succeeded in that) and the third to do a bit of beach combing. Nothing much washed up, but we did find a number of live Necklace Shells (Euspira catena). These gastropods hunt bivalves in and on the sand; if you see shell valves with a neat little hole in them, you know they were victims of this predator. They are name after their necklace-shaped, sandy egg capsules (see here).

This one is about as big as they get. Their cousins in the North-East of the Pacific Ocean (Euspira lewisii) are something else though, take a look at this!

Portuguese Man O’ War

Posted on by under beach combing, cnidarians

It is that time of the year again: gales, rain and darkness. The only good thing about late autumn/winter to me is that the wind blows interesting things on the beach. Portuguese Men o’ War (Physalia physalis) have been a common sight the last few years (see this post from 2017), perhaps more so than it used to be, but not sure this has been properly investigated. Yesterday we saw several dozen at Loe Bar near Helston, including the smallest specimen I have seen so far. No By-the-Wind-Sailors Vellella and no Violet Snails Janthina, and definitely no Porpita or Glaucus; maybe someday!

Portuguese Man O’ War at Gunwalloe Church Cove and Dollar Cove

Posted on by under beach combing, jellies

The weather today was pretty bad, but it was still very nice to go for a quick stroll on the beach; we chose a new destination: Gunwalloe near Helston. The beach and cliffs here are more reminiscent of some of the North Coast spots, quite barren. At the moment, Facebook and Instagram are overflowing with pretty pictures of washed up Portuguese man o’ wars (or Portuguese men o’ war?) in Cornwall, but we only saw two small shrivelled up ones (at Holywell Beach) so far. It was therefore great to see ten or so on the high tide strand line at Dollar Cove and Gunwalloe Church Cove. The smaller ones measured only five cm or so, with the largest one close to 20 cm (the size refers to the pasty-shaped, gas-filled float or pneumatophore). Unlike true jellyfish, which can move by contracting muscles around their bell, the Portuguese man o’ War (Physalia physalis) just sails. More amazingly, they actually are not individuals but colonies comprised of different, specialized individuals (it is getting late writing this, so I will lazily refer to Wikipedia). Stunning colours and truly great finds!