I love some of the strange flotsam that can dot our coastline – especially after a wild and woolly easterly. It is humbling to consider the amazing, lesser-known creatures that live but an arms-length into our oceans – yet that we so rarely see.
If only Darwin had been able to take the deepest breath – or better, had had an oxygen tank, flippers and a well-sealed mask – and had thereby been able to visit, browse, and better conceptualise the seafloor … what a cornucopia of riches would have awaited him. Notwithstanding his lack of modern diving equipment, never doubt that the great man still tried – and succeeded, far beyond our meagre pottering!
Yet, strange and unusual beasties are occasionally strewn on the rock shelves and beaches of the surf coast. From time to time on the Facebook ‘One and Only Lorne community Noticeboard’ site, a photograph appears with a ‘what is this?’ question attached.
One such photo was recently posted with its ‘does anyone know what this is’ query … the unfailing answer being: a sea pen. A recent rock-marooned one is shown in the photograph, an adjacent ‘in-life photo being shown for comparison.
While for the curious, a recent paper in the European Zoological Journal [2018] “The withdrawal behaviour of the red sea pen” makes interesting reading for those inclined [1], Darwin beautifully described these animals – yes, they are animals, not seaweed – in his unmatched scientific masterpiece: “Journal of researches into the natural history and geology of the countries visited during the voyage of H.M.S. Beagle round the world under the command of Capt. Fitz Roy, RN.” [Page 99 in: Darwin CR, 1845: 2nd edition].
I have edited his longer description [with apologies] as follows:
“… [the sea pen] consists of a thin, straight, fleshy stem with alternate rows of polypi lining each side of an elastic central axis. They vary in length from eight inches to two feet. At low water, hundreds may be seen, projecting like stubble, the truncated [ferny] end upwards, a few inches above the surface of the muddy sand. When touched, they suddenly withdraw and nearly or quite disappear [by a contraction of] a highly elastic lower extremity …”
The intellect and curiosity of this unparalleled giant of humanity simply astounds.
Sea pens are found in tropical and temperate waters worldwide, their realm stretching from the inter-tidal [littoral] shore to as deep as 6,100m. They are named for their resemblance to antique quill pens … indeed, very much like the pens that Darwin would have used to write his treatise. Fossilised sea pens have been found in shale from the Cambrian period, dating their known presence to around 500 million years ago. While Darwin found specimens ‘from eight inches to 2 feet’ long, some have been found that are more than 2m in length.
While they are related to anemones – not a surprise – they are close cousins of jellyfish too … and that one ‘got’ me! A favourite delicacy for starfish, many species are an under-sea equivalent to the glow worms that we see so frequently in the dank ferny under-hangs of the Otway bush … they emit bioluminescence when touched, and glow! You will find it quite extraordinary to Google ‘sea pen’, hit images, and scroll through the variety and beauty of these amazing creatures, and their stunning luminescence.
But sea pens are not the only storm-tossed beasties to find! Chunks of driftwood, stalks of kelp, or cuttlefish bones can often be found, covered with crops of muscular, waving trifid-like goose barnacles. I used to find goose barnacles a bit creepy, their multi-jointed necks stretching and contracting in their desperate search for seawater when tossed high onto the sand or rock. Now, I rather pity them and toss them back underwater before they die.
Known as the ‘Mariners Nemesis’, Ocean Navigator [1/1/2003] reports that … “no sea creature wreaks more havoc for the mariner than the barnacle. They quickly attach themselves to boat hulls, keels, rudders, prop shafts, props … every underwater surface possible. By causing considerable drag, a vessel’s speed diminishes by as much as several knots, and the fuel efficiency of powerboats plummets some 40%. It is estimated that barnacles inflict annual worldwide costs of ~$320 million.”
Barnacles may not be a subject to raise in convivial conversation at the Lorne Angling and Aquatic Club over a sundowner beer!
One other beastie – better known for its butterfly-wing-shaped seashell segments but lesser seen in its intact form – is the chiton, a mollusc related to the ancient trilobite. It is made up of eight shell plates that articulate, one with another, and allow the animal to move over uneven rock a bit like an all-terrain army vehicle – or the familiar garden slater.
They, too, are more commonly seen after a disturbed sea, when the current dislodges them from the safety of their underwater rock crevice. They are a culinary delicacy in some parts of the world.
These and many other unexpected joys await the watchful beach walker … so as you walk the shore for exercise, be inquisitive, too, for true wonders await the curious!
Reference
John Agar
