Oceanarium 1

Giant green sea anemone and starfis from the North West Pacific Coast

Just a colourful picture of marine creatures in a touch pool at the Oregon State University Hatfield Marine Scence Center on the North West Pacific Coast – a bright green giant sea anemone (Anthopleura xanthogrammica) with orange and purple starfish (sea stars). I wrote a full post about my visit there several years ago. I also had the pleasure of finding the same fabulous creatures in the wild on the low tide beach near Yachats further south along the coast.

More Rayed Trough Shells at Rhossili

Living Rayed Trough Shell in a shallow tide pool on a sandy beach

Following the line of the limestone cliffs towards Kitchen Corner as the tide receded, the tide pools and beach were littered with dozens of living Rayed Trough Shells (Mactra stultorum Linnaeus) as they popped up to the surface of the sand. I don’t quite know why they chose to do this but it afforded an opportunity to see the living animal as opposed to the dead ones and empty shells that wash up more frequently on Rhossili Beach.

Two pale fleshy tubes joined together were extended between the two hinged shell valves. One inhalent siphon for sucking water with suspended nutrients inwards, and one exhalent siphon for dispelling de-oxygenated water with bodily waste products. I was afraid that these bivalved molluscs would die while gaping and exposed to the air, so I picked up a few and put them in the water of the pools but they were not very lively and did not re-bury themselves. I was surprised that no-one else seemed to notice them. Even the dog that I saw appeared more interested in splashing in the pools than snacking on the free harvest.

Oregon Sea Anemones at the OSU Hatfield Marine Science Visitor Center

Sea anemone in the Touch Tank at Hatfield Marine Science Center, Oregon, USA.

Whilst in Oregon a few years back I explored the seashores along the North West Pacific Coast, and found fascinating and varied forms of seashore creatures. I also visited the Oregon State University Hatfield Marine Science Center which is an excellent place to find out all about the region’s marine wildlife. It also provides a wonderful opportunity to get up close and personal to many inter-tidal creatures by providing a Touch Tank or simulated tide pool. It was fantastic to be able to photograph at close quarters many varieties of sea anemone which I had only been able to spot with difficulty in tide pools and surge gullies on the rocky shores themselves.

Here are some images of the large and colourful sea anemones (with other marine invertebrates) representative of the types that could be encountered locally in the wild.

Sea anemones in the Touch Tank at Hatfield Marine Science Center, Oregon, USA.

Sea anemone in the Touch Tank at Hatfield Marine Science Center, Oregon, USA.

Sea anemones in the Touch Tank at Hatfield Marine Science Center, Oregon, USA.

Sea anemone in the Touch Tank at Hatfield Marine Science Center, Oregon, USA.

Sea anemones in the Touch Tank at Hatfield Marine Science Center, Oregon, USA.

Sea anemone in the Touch Tank at Hatfield Marine Science Center, Oregon, USA.

The Touch Tank at Oregon State University Marine Science Center

COPYRIGHT JESSICA WINDER 2013

All Rights Reserved

Soldier Crabs at Cape Tribulation

Soldier Crabs at Cape Tribulation (1) - A tiny individual Soldier Crab (about 1 cm across carapace) on the muddy wet sand at Myall Beach near Cape Tribulation, Queensland, Australia.

Soldier Crabs are a phenomenon. They are not very big or very special to look at but the behaviour that they exhibit is spectacular. For some reason that scientists do not fully understand, these tiny crabs (about 1 centimetre across the carapace) will suddenly emerge from the wet sand of the lower shore in specific tidal conditions, gather in vast numbers, and march across the beach. Millions of them. Armies of them. Not scuttling randomly sideways like normal crabs but walking forwards. Then they disappear again just as quickly by cork-screwing themselves down into the wet muddy sand. If you stop and stare at the surface sediments, you can see the sand grains heaving as the little creatures excavate burrows below, presumably extracting microscopic food particles from sand they eat, and bringing new deposits or casts to the top.

While I was walking along Myall Beach near Cape Tribulation in Queensland, I was thinking that the vast sandy shore was a bit disappointing from the marine invertebrate point of view. Then I suddenly became aware of extensive dark shadows moving across the surface – looking rather like wind-blown sand. As my eyes focused on these erratically-moving darker patches, I realised that they were battalions of moving crabs. If I stood still long enough, more small crabs would emerge from the wet sediments at my feet, as if on some unknown cue, congregate together and march away, joining the horde and gathering new recruits on the way.

The crabs probably belong to the Family Myctyridae but I don’t think they are Myctyris longicarpus on the basis that the carapace colouring and markings are different in the specimens I photographed. The Soldier Crabs are abundant in this location because the tidal flats are enriched with nutrients brought down from the mountains by a river that flows through the tropical rain forest – reaching the beach as Myall Creek (complete with crocodiles).

The short video clips attached to this post – best viewed without sound because the wind blowing over the microphone is a bit intrusive – demonstrate some of these Soldier Crab habits.

COPYRIGHT JESSICA WINDER 2013

All Rights Reserved

Mussels at Broughton & Whiteford

Wild edible mussels (Mytilus edulis L.) thrive around the Gower coast in South Wales. Although the area is perhaps better known for cockles (Cerastoderma edule L.), mussels grow in great abundance and are the second most important shellfish exploited in this area.

Good spatfalls result in millions of tiny mussels seeming to settle on every available surface that is subject to inundation by the sea, if only fleetingly at high tide or even just spray from the incoming tide. Rocks and boulders are obvious surfaces but strands of algae and living limpets also provide suitable habitats. The upper rocky shores appear to glisten with a richly textured carpet of the new generations of this bivalved mollusc. From a distance the mussel shells look black but, up close, it’s possible to see just how colourful and patterned some of these shells can be.

Not all the young mussels survive. These small seashore creatures compete for space on the settlement substrates. Some specimens fail to make it to maturity. Those that outlive the others can grow to good size. I feel particularly sorry for the poor old limpets which are increasingly weighed down as the covering mussels grow larger and larger.

Storm event and natural mortality can result in huge numbers of empty mussel shells on the beaches. Mostly, the empty shells are found with the two halves of the shell (the valves) stuck together by the ligament, as in life. They can look like decorative dark blue butterflies settled en masse on the sand. The last time I visited the place where Broughton Bay and Whiteford Sands meet, the strand-line was thickly covered with very smelly mature dead mussels on which the local gulls were feasting.

It is the small seed mussels that are collected regularly at extreme low tides from the boulders and pools around the old rusty iron lighthouse at Whiteford Point. In the next posting I’ll talk about how this is done and what happens to the millions of baby mussels that are collected.

COPYRIGHT JESSICA WINDER 2012

All Rights Reserved

Bright blue blobs on the beach

By-the-wind-sailor, Velella velella (Linnaeus), with bright blue oval jelly-like body and transparent chitinous float, washed ashore on the sandy beach at Rhossili, Gower, South Wales, UK (1)

On a recent walk along the strandline at Rhossili, my eye was drawn to something small and very bright blue amongst the seaweed and debris. I thought at first it was a bit of plastic flotsam – but I was really surprised to discover, when I stooped to pick it up, that it was organic and jelly-like . Although it was a bit worse for wear, I could see that it was the remains of a By-the-wind-sailor, Velella velella (Linnaeus). There were several of these bright blue blobs washed-up on the sand.

You can just about make out the damaged fringe of tentacles on the edge of the body in the photographs. Apparently, these small jellyfish-like Hydroids can be driven ashore in large numbers by southerly and southwesterly winds at any time of the year – even as far north as the Hebrides. In the past, I have only ever seen the internal chitinous floats, which look like tiny transparent boats with triangular sails.

By-the-wind-sailor, Velella velella (Linnaeus), with bright blue oval jelly-like body and transparent chitinous float, washed ashore on the sandy beach at Rhossili, Gower, South Wales, UK (2)

By-the-wind-sailor, Velella velella (Linnaeus), undersurface of the bright blue oval jelly-like body with fringe of tentacles, washed ashore on the sandy beach at Rhossili, Gower, South Wales, UK (3)

By-the-wind-sailor, Velella velella (Linnaeus), with bright blue oval jelly-like body and transparent chitinous float, washed ashore on the sandy beach at Rhossili, Gower, South Wales, UK (4)

COPYRIGHT JESSICA WINDER 2011

All Rights Reserved