Nerite Shells at Port Douglas

Posted on April 25, 2013 by winderjssc

Nerite Shells are very common inhabitants of rocky shores on the Queensland coast in Australia; and they generally have a wide Indo-Pacific distribution. There are several species but the specimens shown here are Nerita costata Gmelin and were photographed at Port Douglas.

They have a characteristic appearance with thick black rounded ridges spiralling around the shell whorls, with lighter coloured furrows between them. The spire is blunt. The aperture opening is roughly semicircular with a specific arrangement of protruberances or ‘teeth’. The odd-shell-out in pictures 1 and 2 is a Mulberry Shell or Granulated Drupe (Morula granulata Duclos) which has an odd look with spirals of dark rounded bumps vaguely resembling a bunch of grapes or similar.

Queensland Seaweed – Tricleocarpa cylindrica

Posted on April 24, 2013 by winderjssc

At least, that’s what I think this is! If I’m wrong, I am sure someone will let me know (please?). There are several calcareous red seaweeds growing along the Queensland coast. I found two kinds. Tricleocarpa cylindrica is pink when it is growing and still attached – but it fades and bleaches out to white once it is detached and washed ashore.

It forms a clump of repeatedly forked cylindrical branches (Cribb 1996). Some of the branches are slightly corrugate (with ridges) and you can see this if you click and enlarge on the first two photographs of this Post. There is a light calcification giving the plant a degree of stiffness but not so rigid that it cannot be easily crushed. This species was also known as Galaxaura cylindrica and G. oblongata at one time. It lives attached by a disc-like structure subtidally on sheltered and semi-exposed shores. The specimens shown here were found on Normanby Island and Cape Tribulation beaches.

Cribb, A. B. (1996) Seaweeds of Queensland – A Naturalist’s Guide, The Queensland Naturalists’ Club: Handbook No. 2, published by The Queensland Naturalists’ Club Inc., Brisbane, ISBN 0 9595607 1 8.

Wild Oysters on the Queensland Coast Part 2

Posted on April 22, 2013 by winderjssc

The oysters that I found on the rocks at the northern end of Three Mile Beach in Port Douglas were so different from the ones I had seen at Cape Tribulation that I wondered if they were oysters at all.

The identification of Rock Oysters of the Saccostrea Group in the Indo-West Pacific is a fairly hot topic and some very interesting work was completed a few years ago to try and sort out what is what. See the work of Katherine Lam and Brian Morton.

On the basis of shell morphology, I think the oysters illustrated in this post are Saccostrea mordax which are distinct from the other Saccostrea species in having regularly-spaced grooves radiating from the umbone to the ventral margin of the right valve, the triangular shell shape, and finely plicated valve margin (with regular m-shapes). The left valve is completely attached as in the other species of Saccostrea such as cucullata, glomerata, and kegaki which are all morphologically similar to each other with an oval, deeply cupped left valve and a smaller, relatively flat right valve with slightly plicate, raised margins.

The molecular study by Lam and Morton (2006), based on samples obtained from along the whole of the Australian coastline, clarifies what is known about rock oyster biogeography. The identification of the oysters shown here from Port Douglas tallies with the distribution of Saccostrea mordax that is now thought to have a range from the tropical eastern coast of Australia, along the northern coast and throughout Western Australia. S. glomerata only occurs on the south-eastern coast of Australia on temperate shores from southern Queensland to New South Wales while S. cucullata shares the geographical range of S. mordax. One exception, based on someone’s personal observation – and not as a result of inclusion in the mitochondrial DNA work – is that putative S. mordax also occurs, but in much lower numbers, on shores dominated by S. glomerata around Moreton Island and Sydney.

Wild Oysters on the Queensland Coast Part 1

Posted on April 20, 2013 by winderjssc

I have written a lot about the natural variations in oyster shells belonging to the British Native, Flat, or European Oyster, Ostrea edulis Linnaeus. However variable these shells may be, it is always possible to identify the shells as belonging to that species, and to distinguish them from other species.

In Australia and the Far East, the oysters that grow wild and naturally on the tropical shores include several species of Saccostrea which can be difficult to differentiate from one another because of the diversity of their outward appearance. The morphologies of Saccostrea glomerata, Saccostrea cucullata, Saccostrea kegaki, and Saccostrea mordax, are so variable and overlapping that is not always possible to tell them apart by eye. As with so many other groups of organism currently being investigated (marine algae for example), it is only by use of mitochondrial-DNA analysis that true identities and relationships can be established (Lam and Morton 2006).

Which brings me to a discussion of the Rock Oysters that I photographed in several locations on the Queensland Coast. The images shown in this Posting were taken at Cape Tribulation in tropical Far North Queensland. Just going by the external characteristics, I suggest that they may be Saccostrea glomerata – also called the Sydney Rock Oyster. However, the differentiation of that species from Saccostrea cucullata is so problematic at times even for experts that oysters like this are frequently given both names, S. glomerata cucculata.

In following Posts I’ll show oysters growing in Yawarra Bay, Trinity Bay, and Port Douglas for comparison with these from Cape Tribulation. The shells from the rocks at the northern end of Three Mile Bay at Port Douglas look very different from the others and I think that they may be Saccostrea mordax. I’ll also refer in more detail to the Lam and Morton paper:

Lam, K. and Morton B. (2006) Morphological and mitochondrial-DNA analysis of Indo-West Pacific Rock Oysters (Ostreidae: Saccostrea species), Journal of Molluscan Studies (2006) 72: 235 -245, Oxford University Press on behalf of The Malacological Society of London.

Bridal Veil Stinkhorn

Posted on April 18, 2013 by winderjssc

Seeing a beautiful photograph of this fungus over on the Blog Dadirridreaming written by Christine Whitelaw, I remembered that I had also photographed a large group of these, typically tropical rain forest species, growing on the roadside in Trinity Beach, Queensland, Australia, several years ago. It was a cultivated patch with shrubs and a layer of bark litter on the ground. A hose pipe was in position to automatically water the area.

I was amazed to see these strange phallus-shaped fungi growing in such profusion. Some were specimens fully emerged; and others were still in egg-like structures just protruding from the ground from which new specimens would soon emerge. The last photo (11) in the series of images in this posting shows a double-headed specimen.

These weird and wonderful fungi have been called many things – Bridal Veil Stinkhorn, Long Net Stinkhorn, Crinoline Stinkhorn, Basket Stinkhorn, Veiled Lady, and Bamboo Fungus ….but the Latin name for the fungus is Phallus indusiatus. There is a good and well-illustrated description of the species over on mysabah Blog published by Murphy .

Queensland Seaweed – Turbinaria ornatum

Posted on April 18, 2013 by winderjssc

This is the Spiny Tops seaweed, Turbinaria ornatum, photographed at Cape Tribulation in Queensland, Australia. Superficially, it looks like the seaweed Sargassum crassifolium featured in a previous Posting. However, if you look closely, you can see that here the ‘fronds’ are much thicker and rounder. They are actually the expanded ends of small branchlets. They look a bit like small cookies that have been cut out of thin dough with a serrated-edge cookie cutter.

A. B. Cribb in his book Seaweeds of Queensland, A naturalist’s guide (ISBN 0-9595607-1-8) says about this species that:

The axis bears closely placed top-shaped branchlets with rigidly spiny margins. Eventually a gas-filled cavity develops in these branchlets and the buoyancy keeps the plant erect when submerged. This species is restricted mainly to the tropics where it is common on coral reefs.

Damon Ramsey in his book Ecosystem Guides, Tropical Seashores of Australia (ISBN 978-0-9757470-6-3) tells us that in these very distinctive seaweeds:

Along the top half of the stalk many smaller branchlets grow off to form a dome shape, and each has flat, star-shaped spikes at the end. They can be common in the murkier sandy shallows, and sometimes wash up on tropical beaches.

Queensland Seaweed – Sargassum crassifolium

Posted on April 16, 2013 by winderjssc

Sargassum crassifolium is my best guess for the identity of the seaweed in these photographs. This is just one of eight types of Sargassum washing ashore on the Queensland Coast in Australia. I thought at first it was something called Spiny Tops, Turbinaria ornata, but although I did find one specimen of that, most were S. crassifolium. The features that distinguish it from Spiny Tops are the arrangement of the fronds (leaves) on the stem, the relative thinness of the fronds, the shape and distribution of the spines arround the edges of the blades, and the presence of small round floats.

In Seaweeds of Queensland – A Naturalist’s Guide, The Queensland Naturalists Handbook No. 2, by A. B. Cribb, 1996, Kingswood Press, Queensland, ISBN 0 9595607 1 8, it says about this free-floating brown alga:

The up-curved leaves of this species are relatively short and rigid. In the upper part the spiny margin is double. The species is mainly a tropical one but is occasionally found in the southern part of the State.

Species of Sargassum have been used as food in various parts of the world, particularly China, Japan and Hawaii. Their habitat is the subtidal region on semi-exposed shores.

Queensland Seaweed – Halimeda sp.

Posted on April 15, 2013 by winderjssc

This is an odd-looking one! It looked a bit like small potato crisps threaded to make a necklace. It’s really a green seaweed which is also calcareous. This piece has become bleached white after detaching from its original settlement on a rock or coral, and then washed up on the beach at Port Douglas on the Queensland Coast in Australia. It is a species of Halimeda, probably Halimeda discoidea but I’m not certain about that.

Mangroves at Port Douglas

Posted on February 27, 2013 by winderjssc

These brightly coloured leaves have fallen from mangrove trees growing on the edge of the sandy beach at Port Douglas, Queensland, Australia. The trees shed their leaves steadily throughout the year and sometimes the leathery leaves are trapped for a while on the beach – amongst the tangled above-ground root systems, or snagged by algae-covered emergent aerial roots, and clumped behind boulders. Leaves that are washed into the sea can accumulate in large numbers and return with subsequent tides, forming heaps along the strand-line. I loved the contrasting colours of the fallen mangrove leaves on the sand; and the way that they made a thick bright soup in the sea that rhymically moved with the waves (as in the video clip shown below).

Queensland Seaweed – Botryocladia leptopoda

Posted on February 22, 2013 by winderjssc

Compared with the coast of Great Britain there were relatively few seaweeds on the beaches I visited on the Queensland coast. However, the red seaweed illustrated here was one of the most unusual in appearance. I found it washed up on the sandy beach at Cape Tribulation. It resembled a mass of molluscan or fish eggs – a bit like glistening caviar.

I photographed it from every angle and concluded from the way the swollen ‘leaves’ or ‘eggs’ were attached to branching stems that it was indeed a type of marine alga. It wasn’t till I obtained a copy of the book Seaweeds of Queensland – A Naturalist’s Guide (by A. B. Cribb of the Queensland Naturalists’ Club: Handbook No. 2, 1996, ISBN 0 9595607 1 8) that I could verify its identification. In fact, it is the same species that is featured on the front cover of the book – Botryocladia leptopoda (J. Agardh) Kylin.

The specimen in my own photographs has been affected by the hot sun and most of the ‘leaves’ have dimples in them where they have begun to shrivel out of water. Apparently, the common name is Grape Weed and to quote from the above book,

the densely placed vesicles clothing the branches make this one of the most beautiful red algae in Queensland. Large specimens may reach 40 cm in length. The generic name is derived from the Greek botrys – bunch of grapes, and clados - branch.

Its habitat is mainly in the sub-tidal region in sheltered and semi-exposed areas but also occasionally in shaded pools. Intriguingly, this lovely seaweed is thought to contain chemicals with important medicinal properties. Research is being conducted into these properties in connection with the treatment of lymphatic filarial parasites.

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