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All washed up

Jeremy Torrance web producer Jeremy Torrance web producer | 15:08 UK time, Thursday, 5 August 2010

What can the tide line tell us about the wildlife living under the seas? Emma Brennand visited Perranporth Beach to discover more.

Many of the plants and animals that wash up on our beaches have drifted for hundreds often thousands of miles from a place most of us will never visit. To delve into this dredged up world, I visited Perranporth Beach in Cornwall with Becky Seeley, Biological Records Officer at the Marine Biological Association.

The sandy Perranporth beach extends for up to two miles at low tide. It also faces west. Two factors which make it the perfect resting place for drifting cargo from across the Atlantic.

Becky and I started off by exploring the strandline, the area where debris is deposited.

In the past, I'd always disregarded this area of smelly seaweed but Becky assured me it's a treasure trove. And true enough after exploring it, it became obvious it is its own little micro-environment positively crawling with life.

The seaweed provides an important food source for insects, Becky explained, which in turn may be eaten by coastal birds. As if to prove the point, just this week an extremely rare beetle was found happily residing in the stinky strandline on a Dorset beach.

Spiral wrack (Fucus spiralis)
kelp-bunch.jpg

Along the strandline in Perranporth, we found an six different types of seaweed including a rare type of eel grass (which looked a lot like a spring onion) which must have drift to the beach from a more sheltered cove where it grows in lawn clusters. The rocky outcrops and pools along the beach were home to the usual suspects of mussels and limpets.

Blue mussels (Mytilus edulis) with gutweed (Ulva intestinalis) on rock
blue-mussels.jpg

Leaving the smelly-buzzing strandline behind, we headed to the sea shore in the hope of finding treasure in the sculpted shape of a mermaid's purse.

Skates, rays and sharks all produce egg cases, also known as mermaid's purses, that house their developing offspring. The juvenile animals can take up to 12 months to develop.

Sure enough, we didn't have to look for very long when we stumbled over this lesser-spotted cat shark egg case. We made a quick note of the type and location so that we could report our sighting to the Shark Trust's great egg case hunt and carried on along the beach. (Download the Shark Trust's egg case ID guide if you're interested.)

Small-spotted cat shark egg casing (mermaid's purse)
mermaids-purse.jpg Egg casings come in all shapes and sizes. The smallest case we saw was the next one we found: the common whelk's egg case.

Whelk egg casing, also known as fisherman's soap or sea wash balls
whelks-casing.jpg

A few meters further along we came across the common sight of a bird feeder... erm, cuttlefish bone. These white brittle objects are made up of small compartments that the cuttlefish fills with gases and uses as a buoyancy device to manoeuvre it though the water.

Cuttlefish bone
cuttlefish-bone.jpg

One marine animal that is getting washed up more and more on UK beaches is the jellyfish. The little compass jellyfish we found is easily identified by its radius-stripes and thin tentacles. But beachcomber beware... even dead compass jellyfish can pack a punch with their stinging tentacles.

Compass jellyfish
compass-jellyfish.jpg

As the inevitable clouds moved in, we headed back. Even as we did Becky spotted another interesting object. An ordinary looking lump of seaweed had an interesting stowaway attached, the bouy barnacle.

These little soft-shelled barnacles attach themselves to floating objects and then go where the tides take them. Usually they're found in warmer waters but in recent years large numbers have been washed up on UK beaches. One school of thought believes that the increase in plastics in the seas allows the juvenile barnacles a float to attach themselves to.

Knotted wrack (Ascophyllum nodosum) with bouy barnacle (Dosima fascicularis)
drifting-barnacle.jpg

Once back at the office we registered all findings with the MarLIN's recording scheme. Anyone can register their sightings and this information can be used by Becky and her colleagues at the MBA to map changes is marine life across the UK.

Have you explored the shores this summer? Found any sea monsters or need help IDing your finds? Let us know in the comments below and post your photos in our Flickr group. If you're planning a jaunt, try the Marine Conservation Society's Good Beach Guide for ideas on where to go.

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