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Here be dragons - and cows

23/3/2021

3 Comments

 
By Mark Robertson
 
ONE evening, Pablo Picasso and Salvador Dali got together for a session of drinking absinthe and magic mushroom tea. Once suitably inspired, they decided on a challenge: who could design the most outlandish and bizarre fish? This is what they came up with.
Picture
Weedy Seadragon, Flinders, Western Port, 2007. Photo: Sascha Schultz / iNaturalist.org. by Attribution-Non Commercial
Picture
Ornate Cowfish male. Photo: Julian Finn. Museums Victoria
Now the above scenario may not be entirely factual but it remains the most plausible explanation for the existence of the weedy and leafy sea dragon and the ornate cowfish that I can come up with. And yes, they are very real local members of our sub-aqua environment.
 
Evolutionary theory tells us that species evolve to fill a particular niche – a home within a habitat whereby an organism can live and prey upon other species, and be preyed upon. The entire process is mutually beneficial and contributes to the wondrous tapestry of life that is the biosphere.
 
As a trained zoologist, I can usually envisage how a species, be it plant, animal or microorganism, fits into a niche. But for the life of me I cannot comprehend the purpose of these fishes. They appear to exist “just because they can”. Does this indicate the presence of a “divine designer” with way too much time on their hands, or simply that my tiny human brain is not worthy of understanding the true complexity of life on our planet? I tend towards the latter.
 
Enough philosophical rubbish, let’s explore the reality of these strange and beautiful Bass Coast residents. We are very fortunate that both types of these “denizens of the deep” inhabit the nearshore waters of our bays, estuaries and coastal waters. Most of us live within a few minutes of the Bass Coast and all you need is a mask, snorkel and definitely a wetsuit. I would encourage you to take the plunge and explore our inshore waters – another bonus of living here in paradise.
 
These species are genuine fishes, possessing gills, fins and a vertebral column, but both are lacking in scales, instead being encased in bony plates with a leathery skin.
 
First to the dragons. There are two local species – leafy and weedy. The weedy is the larger of the two, growing to approximately 45cms in length. They are found in coastal waters along the southern Australian shores, roughly from Sydney to Perth. However, the leafy sea dragon is found only as far east as Wilsons Promontory.
 
The leafy sea dragon is the marine emblem of South Australia and the weedy is Victoria’s marine representatives. Both are totally protected by law. The leafy is more flamboyantly decorated with leafy appendages, and the fins are small and transparent. Their diets consist of small invertebrates such as shrimps which are delicately sipped via the long, small mouth. The head is horse-shaped – these species are seahorses, although they lack the prehensile (grasping) tail of other seahorses. They are unable to hold on to the strands of kelp or seagrass that provide habitat and camouflage as they scoot sedately and rather majestically around the watery kingdom. This leaves the slow-moving seadragons susceptible to stormy conditions and is the reason that many are found beachwashed and dead after bad weather. ​

Picture
Weedy Seadragon, Phyllopteryx taeniolatus, Photo: Mark McGrouther, Australian Museum
The males carry the eggs around for nine weeks until the perfectly formed miniature offspring hatch. Dragons have no known predators. The main threats to their existence come from marine pollution and ocean acidification, which has the potential to dissolve the calcareous shells of their crustaceous food. In the past they have been collected for the aquarium trade and for use in alternative medicine – I’m sure the Chinese apothecaries would have found a jar of dried dragons useful in some potions.
 
The ornate cowfish is a piscean caricature – a bony box for a body, leathery skin decorated in psychedelic squiggles and spots, and covered in a toxic mucus, googly eyes and a protruding set of choppers that would render Freddie Mercury jealous.
 
Oh, and two rows of horns along its back. Ornate barely begins to describe the fish adequately.
 
Its range is similar to that of the dragons – Merimbula to Esperance – and it is at home among the reefs and seagrass meadows. Reaching an overall length of 15cms, the males are more colourful than the females. Those strong, sharp chisel teeth are perfectly adapted to prising small molluscs from the rocks, the preferred diet of the little marine bovine.
 
Once again, there are no known predators – how does one consume a solid, bony, toxic box? The bright colouration is often used in the animal kingdom to advertise the fact that a species is toxic. (Google “South American poison arrow frog” for a perfect example.) The main threats to the ornate cow are once again marine pollution and habitat loss.
 
My favourite encounter was several summers ago at Cape Paterson. My boat was drifting towards a commotion on the surface of the water where two male cowfish were engaged in a turf war battle of the Titans. Their bodies were half way above the water as they swam furiously in a tight circle, attempting to bite each other. This battle royal continued for at least five minutes.
 
When male animals fight, it’s usually for one of three reasons – territory, food or women. As their territory and food were 15 metres down, I can only assume the object of their desire was floating beneath waiting to claim the winner’s superior genetic material – part of her cunning plot for world domination.
 
As I stated earlier in this article, I am unable to discern a purpose for these species, However, it warms my heart to know that they somehow exist to enrich the world.
3 Comments
Linda Cuttriss
28/3/2021 09:12:42 am

Thanks Mark for your delightful and informative piece about these fascinating creatures - and the stunning pictures. Most of all I love your message of not needing to know their purpose - the joy comes from knowing they exist.

Reply
Mark Robertson
28/3/2021 04:30:35 pm

Thanks for your kind words Linda, I was at my granddaughters first birthday party today, and am looking forward to one day explaining the pointless wonderfulness of a sea dragon or starfish to her. Provided that the industrialisation of our marine world is kept in check. AGL and sandminers come to mind here, along with those good corporate citizens at Aquasure.

Reply
Catherine Watson
2/4/2021 02:02:00 pm

I saw my first ornated cowfish this morning in a pool at Harmers. I would never have recognised it if I hadn't just ead about it in the Post. Thanks to Mark for his invaluable natural history series.

Reply



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