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Trilobite ?

A

Anonymous

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Not long ago, I found a dead trilobite-type creature on some rocks at Sully beach (near Cardiff). It was approximately 3-4'' in length and a pale pink colour. It was too big and exotic to be a woodlouse and nothing like any of the other insects you see scurrying about in the rocks.

I didn't have a camera with me and was toying with the idea of taking it to a museum to have it checked out but the friend I was with squeamishly insisted I leave it there on the rocks.

Any Crypto-zoologists out there know what I saw ?
 
Could it have been a horseshoe crab? They've been around a long time; look almost as "primitive" as trilobites. Did it have a carapace and long sharp tail?
 
At first I thought that it may have been a large sea slater but they are perhaps 2.5 to 3 centimetres in length.

I remembered, however, on a camping trip to the isle of arran I saw something that looked like a sea slater but it was closer to 7-10 cms in length.

I have been a wildlife surveyor for many years and we are required to include the coasts of britain. Coastal ecology is one of my favorite fields and I have never seen these creatures described in any of the manuals.

It is possible that you have seen a horseshoe crab that has been subject to predation or exposed to the elements.

You say it was pink........it may have been missing its armour. How does this sound to you?

Another point though, almost all creatures of the sea have the ability to die and become washed up on our shores. Thats certainly not to say that we have less interesting creatures or that odd beasts have not become happily established here.

The things that wash up, whose origins quite often are the gulf of Mexico are fascinating but we also have a diverse living population of odd animals that actually choose to visit our seas.

The Luth turtle, one of natures biggest reptiles (half a ton, I believe) visits our seas on an annual basis as do seahorses and pipefish.

More seahorses that arrive are dead rather than living though.
You also get the usual childrens favorite.....tropical shark egg sacks. These are almost plasticy in feel and jellyfish/balloon like in appearance.
 
I had to add this for the sake of good science.

The creatures that I saw were multiple and alive.
They were scurrying in a seemingly erratic manner on a vertical concrete beach wall. The reason that I identified them as Sea slaters at the time was because like sea slaters, they were only there at night.

I was trying to climb the beach wall in the middle of the night (for reasons best left alone) when I saw them scurrying all over my hand and foot holds. It was a bit horrible to be honest.
 
It does sound like you came across some horseshoe crabs. They are primarily nocturnal, and they do look like trilobites.

Maybe some local relative, since there were many of them and they were definitely alive. This site says they are native to North American Atlantic waters....

Link is dead. No archived version found.
 
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The creatures that I saw were definately not Horseshoe crabs and were most certainly related to sea slaters. They were just unusually large specimens and as yet have not been described, officialy, in Britain.

Horseshoe crabs are actually close relatives of the Arachnid family.
Horseshoe crabs cannot climb and tend to be quite placid on the ground. They prefer sandy beaches rather than rocky coasts which is the type that my coastal sighting came under.

I can only vouch for my sighting as an ecologist and offer advice on Dashwoods. It may have been pink because it was missing its armour but Horseshoes are black. Was its armour pink? Or was the flesh under a missing armour, pink?

Was it sectioned like an armadillo or woodlouse or was it more uniform like a crabs shell? Did it have long legs or short legs?

Slaters/woodlice really dont resemble Horseshoes to the extent that they could be mis-identified whereas Trilobites do.
 
Sully's just around the corner from me at the mo(i'm in dinis powis at he mo:) ) so I'll go and check it out within the next few days, if I find any then I'll try to identify it + scan in a picture for your purusal.
Just a few questions:
Was it in a rock pool or crevice?
Was it dead and/or rotted?
Was it under sea weed?
was the tide out all the way? if so would you say it was in the upper middle or lower shore or the tide line?
did you see it nearer to barry or to lavernock?
 
It might have been a chiton. These are quite trilobite/slater like. And they can also be quite colourful and large.
look at biology.ucsc.edu/classes/bio136/images/molluscs/mollusc.htm
and check out the chitons.
just a suggestion.

Link is dead. Here's a representative replacement image ...

chitons.jpg
 
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What do hermit crabs out of their shells look like ? Maybe with missing claws? Just a thought .
 
Chitons are very slow moving though, iirc, and not really fast-moving enough to be mistaken for a trilobite, I wouldn't think. There are however around 30000 species of crustacea (source) and there are enough of them in the North Atlantic for there to be far more around than you would find in most books on coastal wildlife. I would guess that what you saw was one of the larger slater-like crustaceans.
 
Thanks all for the replies so far.

In answer to St.Clair's questions, the creature I saw still had its armour intact and yes, the armour was sectioned like a woodlouse. It also had two long, fine antennae which were swept back either side of its body. Its legs were just visible either side of its body.

It was definitely the armour that was pink but this could have been discolouration due to decay ?? I have no way of knowing how long it had been dead for.

It did not look like anything like the Chiton in the link posted by Breakfast... or much like a horseshoe crab either - the carapace was less domed than any horseshoe crab I've seen.

To answer Oll_Lewis's questions, I found the creature closer to Lavernock than Barry - it was on a small ledge near the base of the cliff. The tide was completely out.
 
Thanks Littleblackduck. A sea slater is probably the closest match so far. The creature I saw could have been an unusually large sea slater - the basic silhouette was the same - but the creature I saw had no bumps or ridges of any kind on its armour, which was very smooth.
 
Wish I'd known that sooner, I was in BP S&Sclub today I could have checked it out then :) no worries though I'll try to have a look round there before I go up to liverpool.

Here's a site with some good pictures of trilobites on it, it's a fossil market site so the photos are always of their best specimines.
Trilobites
 
thank you minor drag. its nice to be missed. im on holiday in quito, ecuador just now. just visited the galapagos islands- amazing. Keep up the disussion
 
Great picture littleblackduck - but not a very close match with what I saw. Your isopod has too many parts/joints to its armour and the legs aren't delicate enough.

Methinks I'll have to find another of these beasties on the rocks and whisk it off to the museum in a bag.
 
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