Struggles with bivalves

There's a movie that Kevin Costner won't be making.

To improve my knowledge of bivalves, I decided to approach the problem systematically. Rather than identify random specimens from the beach, I thought I'd get out my copy of Mollusca: The Southern Synthesis and work through the groups one by one.

Bivalves, according to the book, are divided into five subclasses. (The authors acknowledge that this is a bit of a dodgy classification but it's one we can work with.) So, I started reading about the first one — Protobranchia.

Protobranchia is defined by the structure of the gills … which aren't present in empty shells on the beach. Bugrit! Millennium hand and shrimp. Oh, yes, there's some alternative arrangement that relies on hinge teeth — one group of protobranchs has a particular array whereas the other doesn't — but other taxa also have ...

I moved on.

The next subclass in the book is Pteriomorphia. This includes scallops, oysters and mussels (but not cockles). And you can identify them from shells even when they're not alive, alive-o.

My rudimentary knowledge of bivalve anatomy carried me through the references to the heteromyarian and monomyarian conditions, which relate to the number and size of the muscles that hold the shell closed. (They are represented by oval or circular scars on the inside of the shell.) But then I got to this bit ...

Ligament type is variable within the subclass. The ligament is elongate, parivincular and opisthodetic in heteromyarian forms, such as mytiloids and pinnoids, duplivincular in arcoids and some pteroids, multivincular in isognomonids, and alivincular and amphidetic in equilateral monomyarians such as ostreids and pectinids.

… and my mind said to me, "When I grow up, I'm going to Bovine University."

So I might take this a little more slowly. I'll keep you informed.

In which I make an effort to learn about bivalves

Until recently, I haven't spent a lot of time on bivalves. Other than as ingredients in a marinara sauce, that is. But now I've been focussing on the crunchy bits on the outside, rather than the juicy insides. It turns out that — contrary to my gastropodal preconceptions — bivalve shells don't all look the same.

Here's one I prepared earlier.

Laternula (family Laternulidae, subclass Anomalodesmata) is a small genus of bivalves living in soft sediments in the Indo-Pacific and Southern Oceans. A few species are common in southern Australia.



Laternulids are easily distinguished from other families. The shells are thin and fragile and are attached to one another by a tricky hinge operated with a pair of ligaments. As with other bivalves, the main ligament is a wedge of elastic protein. Because the shells are so fragile, this ligament is attached to spoon-shaped chondrophores that project into the shell cavity rather than directly to the shell edge. This ligament is also strengthened by a calcareous plate, the lithodesma.


The secondary ligament, which is on the outside of the shells, is formed from a continuous layer of periostracum. Weird, huh?

Laternulids have a few other strange features, such as a fine split in each shell that allows the shells to flex. But then they have an internal buttress that reduces the potential for damage … You can see them both in the photo below.

No wonder they spend all their time sitting in soft mud.

What the ...?

Since a friend told me about Atlantis Removals, I've kept my eyes open for other companies with ... unusual ... names.

Geelong, it turns out, provides rich pickings.

On my way through town today, I spotted Lifestyle Funerals and — the winner so far — Sweeney Todd Medical Waste Disposal. Don't eat that pie.

Cormorants all in a row

No swans at the Swan Bay jetty this afternoon but plenty of little pied cormorants. At one point, there must have been a hundred or more of them lined up along the railing but then someone walked past and they all took off.

The someone was an elderly woman on her afternoon constitutional. She stopped to ask 'Have you ever seen so many shags in one place?'

I had to think about that.





They settled on an abandoned trailer and boats moored in the shallow waters. The little pieds shared the boats with the more retiring little black cormorants. I wouldn't want the job of cleaning off the guano. Could this be the origin of the term 'poop deck'?




Less numerous than the cormorants but nonetheless holding their own were silver gulls, Caspian terns and crested terns.

Caspian tern

Crested tern

White-fronted chats foraged in the saltmarsh, invariably just that little bit too far away for a good photo. The orange-bellied parrots, if they were around, were keeping a low profile.

Where the orange-bellied parrots weren't

So this is another place to add to my list of spots to visit again soon. At this rate, I'll never get to new locations but will be doing an endless round of the old ones. A bit like painting the Sydney Harbour Bridge ...


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Swan Bay jetty on Google Maps

Stranded

Last Tuesday's tide stranded jellyfish on the beach. A couple of dozen blue blubber (Catostylus mosaicus) were laid out along the southern side of the spit at Limeburner's Bay; a handful more on the northern side.

Like other rhizostome jellyfish, blue blubbers lack tentacles and a central mouth. Instead they possess lobed arms, each of which has a mouth at the tip. (Take that, 'Dr Who' scriptwriters!)


The blue blubber is the most abundant big jelly around Melbourne. It prefers sheltered water and estuaries and forms extensive swarms in Port Phillip Bay, where it is harvested under licence for export to China and Japan.

Currently the minimum catch required to maintain a licence is 150 tonnes. Given that the average weight of an adult blubber is a little over a kilo and that they are caught individually in dip nets, that's a shedload of work.

Yet more molluscs in the UK

Cool story from the UK. (HT to Mosura.)

A colony of Mediterranean snails has been found at the UK's Cliveden House, where they have lived in marble-wrapped secrecy for a century.

The snails, never found before in the UK, apparently came from Italy in a balustrade bought by a Lord Astor, a former owner of the mansion.

The traveler, Papillifera papillaris, belongs to the family Clausiliidae. In Europe, clausiliids are found mainly in the south and east. Only about half a dozen species are native to Britain.

They are characterized by long, tapering, sinistral shells that bear a sculpture of fine ridges. The aperture usually has ribs and teeth. Inside the shell is a unique structure — the clausilium — which is a spoon-shaped flap that blocks the entrance when the snail retracts. While the snail is active, the clausilium is tucked away in a groove in the shell wall.

This follows the (relatively) recent discovery of a new species of slug in Wales.

The snails

"… were found by a specialist volunteer who helps us clean the statuary in Cliveden," said the Trust's nature conservation advisor Mathew Oates.

"He went to a talk at the local archaeological society given by a snail specialist, mentioned his find, and it turned out he'd spotted the colony which had almost certainly been there since 1896," he told BBC News.

Aydin at Snail's Tales blogged on the possible dispersal of clausillids by birds. So here's another way they can get around!

_________

ETA: Aydin reports this is old news.

Shakes fist at Broadcasting House.

Damn you, BBC!

Also regrets lost opportunity to make joke about John Profumo at Cliveden House.

Shells on the strandline

Off to Portarlington and Indented Head tomorrow. I was supposed to go today but the rain and wind and hail changed my plans. Don't get me wrong — I love rain when I'm indoors and rugged up. But when I'm digging around for bivalves on a muddy beach …

I've already been out once this week. On Tuesday, I went to Limeburners Bay, near Geelong.


I didn't have time to walk the path that runs along the western bank of Hovell's Creek. That's another item to go on my ever-increasing list of the Things To Do. Instead, it was quick survey of the beach for bivalves (the primary reason for the trip) and a scan of the water for birds (entirely incidental).

A short spit runs out into the bay. To the north, the beach is shallow sand and mud overlying anoxic sediment packed with oyster and Anadara shells. White-faced herons drop in here to search for crustaceans and fish among the sea grass.





At first glance, it looks as though there's not much happening. But there are all sorts of goodies down in the mud, judging by the recently dead shells stranded on the spit. The mussel Xenostrobus inconstans lives in sediments on the upper shore, along with the operculum-bearing pulmonate snails Salinator fragilis. Empty Xenostrobus shells are abundant. Live Salinator even more so.




Lower down are laternulids (top) and tellinids (bottom) and even the introduced bag mussel Musculista senhousia. Musculista lives on the sea grass beds, anchoring itself with a net of byssal threads. Clumps of mussels provide a solid surface in an otherwise soft and sloppy substrate.



The tip of the spit is composed entirely of gastropod shells, the most conspicuous of which are the chunky mud whelks Velacumantus (= Batillaria) australis. Although I encountered a few live individuals on the upper shore, the majority were at or below the low tide line. And by majority I mean there were freakin' millions of them.

Mud whelks feed by grazing on surface deposits and by collecting suspended particles. This second activity contributes to the transfer of organic material from the water column to the sediment. (Don't make me draw a picture of how that happens.) Where the whelks gather in such high numbers, that transfer has gotta be significant.


There are a million stories in the strandline. It's amazing what you can find out when you stick your nose in the mud. Not my target bivalves, as it happens, but lots of other interesting stuff ...

Sea Cliff Nature Walk

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When I was at Portland a few weeks ago, I went for a stroll along the Cliff Top Nature Walk at Cape Nelson. It was a wet and windy day with occasional glimpses of blue sky. Not the best bird watching weather but I saw all the usual suspects in the coastal heath: superb blue wrens, New Holland honeyeaters, little wattlebirds, crimson rosellas and grey currawongs (black-winged form). None of which had the grace to perch long enough for me to operate my camera with my frozen fingers, you understand. So you'll just have to take my word for it.

The walk is about 3 km long and passes through a range of heath types as it runs from the centre of the cape to the coast and back again. Here's the short version, without the squalls that arrived, unimpeded, from Antarctica.

Grass trees near the start of the track

Flame heath (Astroloma conostephioides) brings a splash of colour to the scrub

The endemic soap mallee (Eucalyptus diversifolia)

Echidna mission statement — we take digging seriously

Wallaby tracks

Close to the cliff top, the trees get shorter and shorter until you feel as if you're entering Liliput

The Nature Walk joins the Great South West Walk on the Cape's west coast

Looking north towards Bridgewater Bay

Ballart (Exocarpos) catches the sun

Correa in the shadows

Out of Liliput and into the Shire

Where the rosella wasn't

Meal meme on Monday

I picked up this meme from Wanderin' Weeta. The idea is to mark out in bold the foods you've eaten and cross off the ones you wouldn't touch with a barge pole. Now I know what I've been doing with my time.

1. Venison
2. Nettle tea
3. Huevos rancheros
4. Steak tartare
5. Crocodile
6. Black pudding
7. Cheese fondue
8. Carp
9. Borscht
10. Baba ghanoush
11. Calamari
12. Pho
13. PB&J sandwich
14. Aloo gobi
15. Hot dog from a street cart
16. Epoisses
17. Black truffle
18. Fruit wine made from something other than grapes
19. Steamed pork buns
20. Pistachio ice cream
21. Heirloom tomatoes
22. Fresh wild berries
23. Foie gras
24. Rice and beans
25. Brawn
26. Raw Scotch Bonnet pepper
27. Dulce de leche
28. Oysters.
29. Baklava
30. Bagna cauda
31. Wasabi peas
32. Clam chowder in a sourdough bowl
33. Salted lassi
34. Sauerkraut
35. Root beer float
36. Cognac with a fat cigar
37. Clotted cream tea
38. Vodka jelly/Jell-O
39. Gumbo
40. Oxtail
41. Curried goat
42. Whole insects (Green tree ants straight off the tree!)
43. Phaal
44. Goat's milk
45. Malt whisky from a bottle worth £60/$120 or more
46. Fugu
47. Chicken tikka masala
48. Eel
49. Krispy Kreme original glazed doughnut
50. Sea urchin
51. Prickly pear
52. Umeboshi
53. Abalone
54. Paneer
55. McDonald's Big Mac Meal
56. Spaetzle
57. Dirty gin martini
58. Beer above 8%
59. Poutine
60. Carob chips
61. S'mores
62. Sweetbreads
63. Kaolin
64. Currywurst
65. Durian
66. Frogs' legs
67. Beignets, churros, elephant ears or funnel cake
68. Haggis
69. Fried plantain
70. Chitterlings or andouillette
71. Gazpacho
72. Caviar and blini
73. Louche absinthe
74. Gjetost or brunost
75. Roadkill
76. Baijiu
77. Hostess Fruit Pie
78. Snail
79. Lapsang souchong
80. Bellini
81. Tom yum
82. Eggs Benedict
83. Pocky
84. Tasting menu at a three-Michelin-star restaurant
85. Kobe beef
86. Hare
87. Goulash
88. Flowers
89. Horse (Does camel count?)
90. Criollo chocolate
91. Spam
92. Soft shell crab
93. Rose harissa
94. Catfish
95. Mole poblano
96. Bagel and lox
97. Lobster Thermidor
98. Polenta
99. Jamaican Blue Mountain coffee
100. Snake

How did I miss this?

Christopher Taylor at Catalogue of Organisms mixes land snail systematics and lolcatspeak ... but not in equal proportions.

Green (or silver) and gold

This here is the wattle
The symbol of our land
You can stick it in a bottle
You can hold it in your hand

Monty Python

Even in the depths of winter, there's a wattle flowering somewhere. They are lighting up the woodlands and glowing like beacons along the freeways.

In her Bushland Notes published in the Melbourne Age newspaper in the 1960s, Winifred Waddell wrote this of the winter blooms:

Wherever you go toward the end of August you can see wattle blossom. On the coastal dunes, it is Coastal Wattle, with ... branches hung thickly with catkin-like rods of yellow. In the heathlands it may be Spreading Wattle or Spike Wattle ... In wet places the earliest flowers may be those appearing on Acacia verticillata. This is a graceful shrub, pleasing to the eye.

In northern Victoria you could hardly count the wattles flowering now. Some, like Golden Wattle, are trees, but most are dwarf and bushy and so densely covered with blossom that you hardly see the leaves ...

So here are some glorious, luminous blossoms at the Points Arboretum, Coleraine, and Tower Hill in SW Victoria.