Sunday, May 6, 2012

Shell Fest



Sandwich Bay is within spitting distance of home. At low tide, it's a long sandy beach and there's rarely another person in sight. Bliss. An excellent place to indulge a favourite past-time.

I love beach-combing. In a short time I'd acquired sodden trainers, wet socks, damp jean bottoms, soggy knees and pockets bulging with precious finds (and a good helping of sand). Here's a selection of acquired treasures, although let me say at the outset, that I'm a bit rocky on shell identification so any help would be much appreciated.

I've tried to group my finds in families. First up are bivalve molluscs.

Variable scallop Chlamys varia; a beautiful bivalve with unequal ears (auricles is the correct term for the appendages at the hinge). Lots of salmon pink mottled ones....


...and some were black...


..and one looked like a scallop/oyster hybrid!


Queen scallop Aequipecten opercularis has more equal ears. I'm not sure about my identification but these shells look different (wider?) to the variable scallops above (to me anyway).


The patterning is glorious.


Next up are gastropod molluscs. From left to right I reckon these are; a periwinkle and 4 whelks; common whelk, netted dog whelk, dog whelk and sting winkle.


The whelks have a siphonal canal leading from the aperture. The shell at the top is what I think is the periwinkle - it has no siphonal canal.


The siphonal canal is (I paraphrase from Wikipedia) the channel down which the siphon is extended (in a living animal). The siphon is the structure through which water is pulled into the mantle cavity and over the gill.

We found many common whelks Buccinun undatum. Its scientific name means wavy (undatum) trumpet (buccinum). It feeds on bivalve molluscs by either wedging open their shells or by boring holes in shells and injecting a chemical cocktail. This cocktail comprises of chemicals which soften the shell, paralyse the animal inside and start to digest it. The resulting nutritious soup is gorged on by the whelk.


The netted dogwhelk Nassarius reticulatus is a really pretty whelk with a criss-crossed reticulated patterning. 


Humans are not the only animals to consider oysters a delicacy. I only found a single oyster drill or sting winkle Ocenebra erinacea. Its name suggests a fondness for oysters and it's regarded as a pest on oyster beds.


There's also an Atlantic oyster drill Urosalpinx cinerea which was introduced (unintentionally) to UK waters and is now found off the Essex and Kent coasts.

Is the damage on this tellin (?) caused by a boring whelk?


I got a shock when I picked up these whelks :-))


Hermit crabs. The one on the left is living in a netted dog whelk. The one on the right is in a...well, I wondered if this was an Atlantic oyster drill shell? I'm not sure. Hermit crabs are actually more like a very small lobster than a crab. This one looks as if it could do with a new residence.


There are 15 or so species of hermit crab in UK waters. The most frequently found species in rock pools and on sandy beaches is the common hermit crab, Pagurus bernhardus.

This delicate conical gastropod (1cm tall) looks like a small painted topshell Calliostoma zizyphinum, although it was all pearly, creamy white. I only found the one.


There were quite a few grey topshells Gibbula cineraria. Most were 1cm tall or less.


Gibbula is from the Latin for hump and cineraria means ash coloured. Its name manes little ash coloured hump. It has an umbilicus next to the shell aperture.


Slipper limpets Crepidula fornicata were a regular find. This one is covered in encursting bryozoans.

They are actually gastropod molluscs - even though they're not curly and whorled. I wrote about slipper limpets on my old blog.

All the shells in the next photo are less than 1cm long. Just above the pink scallop and under the 'little ash coloured humps' is a cowrie.

As it's 'spotless' I'm guessing it's an arctic cowrie Trivia arctica. They feed on sea squirts. Very dainty shell which I've subsequently lost :-(

When I was rooting around amongst the sand, I came across this isty-bitsy thing.


From its pentaradial symmetry, its clearly an echinoid of some sort. Appropriately it's called a pea urchin Echinocyamus pusillus.


That's a penny by the way :-))

A picture of a live animal can be seen here. They feed on detritus, marine algae and plankton. Below is the underside.


The mouth is the big hole and the anus is the small hole. Of course, this is only the sun-bleached outer skeleton of the animal.

I thought this was a jelly fish but on getting home and consulting my books, I reckon it's a sea gooseberry Pleurobrachia pileus.


Incredibly I find they are not related to jellyfish atall but are classified in a separate phylum Ctenophora. They move using cilia, which are arranged in rows so give it the name comb-jelly.

I wasn't the only one indulging in a little beach-combing.

Turnstone, Sandwich Bay

Further Information
Sandwich Bay is home to the Sandwich Bay Bird Observatory Trust. Worth every penny of the membership fee. 
The best website I've found, by far, on British marine bivalves is Amgueddfa Cymru (National Museum of Wales)
Field Studies Council webpages on The Seashore.

2 comments:

  1. What a fantastic array of creatures! Lovely finds. :)

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  2. I'm still jealous of your herp-fest ;-)

    ReplyDelete