#006 Crouching Urchin, Hidden Wobbegong

Have you ever heard the fate of the US Cities Service Boston?

May 16th, 1943. Guns up and down the Illawarra coast were trained on the ocean. Rumour of Japanese submarines abounded, and a convoy of American ships patrolled the coast, ready for a fight.

The ships strayed too close to land. At dawn the US Cities Service Boston ran aground in rough seas, trapping her 62 crew aboard. In such stormy seas, trying to swim to the rocky coast was suicide.

As word went up from nearby Shellharbour that the ship was sinking, the 6 Machine Gun Battery camped at Kembla Grange was called in for the rescue. Australian soldiers worked through the day with ropes to bring the Americans bruised but alive back to shore.

But the sea, not sated with the ship in her belly, threw a wave that dragged ten soldiers, Australian and American, back into the brine. Six made it; four didn’t, and those four Australians lie with the Cities Service Boston in the bed of what is now Bass Point Reserve.

And while the US Cities Service Boston is the most notorious shipwreck, it is by no means the only.

But the shipwreck was not the start of Bass Point’s history. The Eloueran Aboriginals have occupied the reserve for the past 20 000 years. Archaeological finds from the reserve include middens, a sacred burial ground, and rare signs of established occupation. And while the US Cities Service Boston is the most notorious shipwreck, it is by no means the only.

 

Leaving the Shellharbour dive shop early on Sunday morning, we hammer along the dirt road to Bass Point in the battered shop truck.

Bushland fringes the road, cut with windows overlooking brilliant sparkling ocean. We suit up in our dive gear admiring the smoky panorama of the northern headlands, Windang Island, the Port Kembla Steelworks, and blue expanse of the South Pacific Ocean.

On any given weekend the reserve will be alive with divers, fishermen and snorkelers. Diving schools frequent the area and at times there are 50 divers in the water. The popular entry points are the Gravel Loader if you want to see Grey Nurse Sharks, and the Gutter for everything else.

The Gutter drops us 3 – 6 m from surface to seabed depending on the tide, and gives instant access a verdant underwater world. The Nursery, Blue Devil Cave and Sponge Garden are all accessed from here.

It is all spectacular. The underwater world exists in a realm unto itself. Once your head is below the water, you are swept away to another life.

The first thing I notice as cool rushes over me is the opacity of the water. On the surface I could see a dozen kilometres to the bow of the ocean disappearing behind the curvature of the Earth. In the water, on an average day, we can see maybe 10 to 15 metres. When cold water is pushing up from the south, visibility can drop to less than 5 metres. Light dims away quickly, plunging me from bright morning to early evening. Everything is magnified. A Maori Wrasse glides by and I reached out and touch it with a giant white finger. My hand looks like my father’s. All around me are the neon yellows and electric purples of other divers’ fins and suits. I look for the solid yellow fins of my diving buddy. I run my fingers around the edge of my hood, and cool water rushes down my neck. My buddy gives a signal: we’re moving forward.

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Fishes shoal around us. Most are young, wrasses, Stripeys and others too young to recognise. Beneath us are bare rocks and dwarf fronds of brown algae. We push into deeper water, the fishes growing larger and the walls of the Gutter opening onto the boulder-strewn landscape of the ocean.

At 10 metres, I spy a pair of juvenile cuttlefishes changing colour with sunlight filtering down from the surface. The algal fans beneath the cuttlefish are iridescent, flashing from pale blue to brown to ultramarine. Two spots on the cuttlefishes’ backs flare white in rhythm with the dappled light. Their smooth bodies, parallel with the seabed, show waves of brown and blue. Their disguise is so flawless that I am almost on top of them by time I notice them. I reach out and stroke one gently on the back. Its whole body flares white, then blue, and it returns to mimicking the flickering light.

The cuttlefish aren’t the only critters I’ve spotted at the last moment: many times I’ve gone to place my hand on a rock only to glimpse the black needles of a Long-Spined Urchin. Peering down into the gap in the rock, I see half dozen urchins. Their black spines shimmer purple and green. At night this horde will creep from between the rocks and feed on the kelp abundant in the warm, shallow water.

Why is the Long-Spined Urchin such a problem?

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#091 Long-Spined Urchin (Centrostephanus rodgersii)

Long-Spined Urchins may be too good at what they do. Not only do they eat the kelp, they also scrape the microalgae from the surface of rocks, creating areas known as “urchin barrens” where nothing else can grow. A large enough group of these urchins will bulldoze a seabed, driving out rock lobsters, abalones, fishes and everything else dependant on the algae for life. Like the plants of the rainforest, algae is the basis of the ocean food chain. Remove it and everything above it has to leave too. The urchins have become so prolific in recent years that they now pose a major threat to fisheries in NSW and Tasmania.

Yet why is it the Long-Spined Urchin such a problem? It’s native, and it used to be that natural predators such as the Spiny Lobster kept its numbers in check.

It turns out that the Long-Spined Urchin is particularly good at adapting to climate change. Warmer, more acidic oceans do not have as great an impact on these urchins as they do on other marine animals. These warmer waters are shifted on the major ocean currents, and carrying Long-Spined Urchins to places they have never been before. Because the urchins were not previously found here, there are few local animals willing to eat them. The urchins are able to take advantage of untapped seabeds and limitless opportunities for growth, becoming a major pest.

In NSW, where the Black-Spined Urchin was always found, overfishing for species like the Spiny Lobster has removed its natural predators. As in Tasmania, the eastern coast of Australia is now facing an expanding population of urchins with nothing to keep them in check.

This must be a real headache for the fishing industry. Urchins can be harvested for their roe (eggs) but as you may imagine, removing eggs from urchins is a time-exhaustive process met with a limited market. The far more valuable trade is in the lobsters and abalones that the urchins drive out. Lobsters alone are worth $369 million a year to Australia, and abalones worth another $173 million. When we think of overfishing, we think of fishes like tuna and sturgeon. Yet here is a case in which the removal of a humble crab could lead to the collapse of an entire ecosystem and the fishing industry dependant on it.

There are animals in the ocean that we never think can be impacted by fishing.

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Another master of disguise.

There are animals in the ocean that we never think can be impacted by fishing. These apex predators seem above all that, immune to hooks and lines, and they hardly seem palatable. I’m talking about sharks.

However, researching wobbegong sharks, that’s exactly what I found. The Banded Wobbegong, one of the larger sharks in these waters, is commonly hooked through the belly. Sometimes the animals are killed (and fished intentionally, sold as boneless fillet or flake), but other times the hooked animal is released back into the water.

This sounds like a happy ending where the Banded Wobbegong gets to live again another day. But in truth released sharks are often badly injured and will die as a result of being hooked. J-hooks tear the shark’s stomach and liver, injuries from which it has little chance of recovery. The use of circular hooks has reduced mortality of captured sharks, but have yet to be instated as mandatory in NSW.

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#104 Banded Wobbegong (Orectolobus halei)

Banded Wobbegongs are well-liked by divers. They are a type of carpet shark, called so because they lie in wait on the seabed. A Banded Wobbegong can grow to 2.5 m, with reports up to 3 m, and they live to a depth of 195 m. The name “wobbegong” is of Aboriginal origin, meaning “shaggy beard” in reference to the weed-like whiskers around the shark’s face.

These weeds are an essential part of the Banded Wobbegong’s camouflage. It becomes invisible on the seabed, resting throughout the day. When divers approach, the Banded Wobbegong waits patiently for them to leave. Bullseyes, Blue Devils and other fishes swim by and the Banded Wobbegong does not flick a whisker.

The use of circular hooks has reduced mortality of captured sharks, but have yet to be instated as mandatory in NSW.

It is only when the shark is hungry that it attacks (this is a lie. A diver leaning on a wobbegong for a photo received a nasty bite on his leg. Touch them and they get bitey.) A fish passes overhead. The wobbegong launches itself from the seabed, inhaling the fish into its wide mouth. Its small sharp teeth prevent prey from swimming out. With a gulp, the shark swallows, and drifts back to the ocean floor.

 

Hiding in crevices and ambushing dinner is all very well. Yet some animals are so deft at camouflage that they hide in plain sight.

The Yellow Umbrella Snail is one of these. The charismatic yellow of this Notaspidea (meaning “back shield”) is anything but clandestine. They are found high up on sponge-encrusted reefs. So how does anyone miss them?

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#029 Yellow Umbrella Snail (Tylodina corticalis)

Well, the Yellow Umbrella Snail is the same shade of yellow as the inside of its favourite sponge. All species in the genus Tylodina, all over the world, feast on species of the same genus of sponge, Pseudoceratina. Set against the yellow background of the masticated sponge, the Yellow Umbrella Snail becomes virtually invisible.

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At 20m, a Yellow Umbrella Snail munches on its favourite sponge.

There’s also the small matter that probably nothing wants to eat the Yellow Umbrella. Pseudoceratina sponges have been the subject of extensive research into cures for breast cancer, owed to their chemical weaponry. These sponges produce rare alkaloids that are antimicrobial, antifungal, cytotoxic and antimalarial, and anti-anything else living inside you. The sponges themselves are so toxic that they have no natural predators outside the Tylodina snails and a few Aplysian nudibranchs, themselves highly toxic.

The question is how do Yellow Umbrellas eat these sponges without being poisoned? It turns out that Tylodina snails can modify the chemicals produced by the sponge and cherry-pick which are best used for their own defence. That charming Yellow Umbrella Snail is actually building a chemical armoury in its body.

That’s something to munch on the next time you see a charmingly coloured mollusc.

 

Next time you’re looking out across the white-capped waves, or even just have fish for dinner, consider the story of what you’re looking at. Wobbegong meat is sold as flake – commonly battered and not at all highly valued. If rock lobsters were sustainably farmed, fisheries would not be facing hordes of urchins which destroy the habitats for those lobsters, abalones and fishes.

Like everything, there’s an app to check if your fish has been sustainably farmed. It was published by the Australian Marine Conservation Society and you can find it right here. http://www.sustainableseafood.org.au/

And then, because we all like a guilt-free trip to the beach, come and join Salty, Keen and I this Saturday the 13th of March on our second voyage to Windang Island. I’ve wrangled a portable BBQ and some chalk and we’re going to have a merry old time counting species on the intertidal. There will even be a prize for whomever finds the biggest Zebra Snail.

See you there!

 

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Watch the Banded Wobbegong’s ambush technique: http://www.abc.net.au/science/articles/2013/07/31/3811486.htm

A chilling look at sea urchin barrens: http://www.abc.net.au/science/articles/2013/07/31/3811486.htm

More on the sea sponges, Pseudoceratina spp.: http://www.telegraph.co.uk/news/health/news/11203823/Sea-sponge-drug-could-boost-breast-cancer-survival.html

Warilla Beach Collection Day

Ever wanted to be a marine biologist for a day? Here’s your chance!
Help count marine snail populations on Windang Island and you’ll be helping protect our oceans.
A BBQ will be available on the day, with some food provided PLUS whoever uploads the best photo of the day to the Gong 151 Facebook page wins a $20 JB-HiFi voucher!

Find out all the glorious details on the 151 Facebook page.

Salty and I will see you there! (He’s out polishing the BBQ as we speak.)

#005 The Kingdom of Clones

One night after dinner in the city, I drove Keen through the winding dark streets of Bellambi and parked on a grassy verge overlooking a narrow strip of beach. The ocean was black. The lights of freight ships could be seen far away across the water. We watched a storm roll in over the horizon. White legs of lightning stabbed between the ships. Fat drops of rain splattered on the windshield. Wynhilde’s windows shuddered in the echo of thunder. We felt very safe in our tin can, connected to the ocean as we were by the onslaught of the storm.

By day Bellambi Rock Pools sit squarely between the long strip of Bellambi Beach and the gravel shoot of the boat ramp. “Ramp” doesn’t do the structure much justice: there’s room for a hundred cars, fish cleaning bays at the seaward end, and bright orange spotlights that stand out starkly all the way from Sublime Point atop the Escarpment.

But the beach is nice. The surfers like it, and I tend to trust their taste in beaches. By the rock pools is a pool where the water sloshes in at high tide, and where you can swim without fear of waves, sharks or freak freight ship accidents. Although on this particular stunning morning in April I did spy a school of pufferfish skirting around the pool’s edges.

Maybe it’s the calmness of the bay. Maybe it’s the fish blood in the water. Whatever it is, there’s an abundance of life amongst the rock pools of Bellambi not found anywhere else in the Gong.

The hunting area is small, even at mid tide. Even so you will find Brittle Stars, Elephant Snails, Eleven-Armed Seastars, Blackspot Sergeants, Common Silversides, Cocos Frillgobies, Spengler’s Tritons, Waratah Anemones, green banks of Cunjevoi sticking out into the ocean, and even if you’re not looking for one, a Gloomy Octopus may find you.

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Tube worm colony atop cunjevoi sea squirts.

Keen and I started high on the beach and worked our way towards the lowering tide line. To our great pleasure we were joined by a photographer and her daughter, who was about 4. The little girl had accompanied her mother on a photoshoot, but her patience only lasted so long, and so the pair ended up at the beach.

I’m always impressed by the amount kids know. At Windang Island a couple of little girls had shown up Keen by naming Zebra Top Snails, limpets and mussels. If kids know that much, and take such delight in combing through the rock pools, I think there really is hope for the future of the ocean.

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Dwarf Cushion Stars feeding in an algae bed.

Chasing gobies in a pool, I noticed the irregular shape of a Dwarf Cushion Star suckered to the rock wall. These tiny seastars are so well camouflaged that Keen did not see them at all, even when he was staring right at them. What started as one on the rock turned out to be dozens of all different sizes, some resting in the sun-dappled water, others slowly twirling in search of second breakfast.

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#092 Dwarf Cushion Star (Parvulastra exigua)

Unlike many seastars, Dwarf Cushion Stars are herbivorous, scraping microalgae from the rock. What makes them interesting is not just their camouflage ability, but the way they reproduce. A Dwarf Cushion Star may mate to fertilise its eggs, which are laid in a sticky mass on the underside of boulders. However, these stars are found all the way from Australia to South Africa. Such tiny stars in such a huge territory are spread out enough that one may never find a partner. In this case, the Dwarf Cushion Star is able to go asexual reproduction – creating a clone of itself. This ensures that even without a mate, the seastars survive another generation, and have another chance to find their perfect somebody.

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Top and underside of Dwarf Cushion Star. The mouth is on the bottom. Note the small grasping hands near the mouth.

As Salty excused himself to chase crabs, Keen and I moved further towards the water, where we could peer beneath the eroded rock shelf into a honeycomb of caves.

Water dripped into pools stained emerald with sea grass. Giant Spengler’s Tritons clustered in the shallows. I peered beneath an overhang to find a colony of dangling red blobs. Each was about the size of a Lindt chocolate ball, shiny and slick and deep, lustrous crimson.

Pressing a finger to the red side, I felt firm, slick flesh, like an overdone jelly. The colony of some few dozen animals was mysterious in its silence. Only a puckered opening in the blob’s apex gave any clue to the creature’s true form. Here there were wriggling scarlet fingers. As if in reflection in the water below, another colony had blossomed into a mass of red fingers like a flower of Cthulhu.

These are Waratah Anemones, prolific and beautiful. When immersed in water they open to reveal tendrils tipped in stinging cells to paralyse small prey. When the water level drops, they envelop themselves in a tight bundle, conserving water and protecting their soft inner parts from damage.

You would never guess from the sight of them, but these strange red flowers are animals.

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#012 Waratah Anemone (Actinia tenebrosa)

Yet their appearance is not the strangest thing about them. That colony beneath the overhang at Bellambi Rock Pools? They are most likely clones of one another. An individual settling on a rocky beach will give birth to live young, well-developed miniatures of the adult form. These babies settle close to the parent, establishing a colony. Clones are able to identify one another, via chemoreception or some mysterious superpower known only to clones. If a genetically diverse anemone attempts to settle near the colony, the clones will attack it, ensuring the Kingdom of Clones.

While clones are highly adapted to their strip of beach, not all Waratah Anemones are genetically similar. An anemone may release its gametes (eggs or sperm) into the ocean’s plankton, where it will be external fertilised by another drifting gamete. The resulting embryo washes up on a distant beach, where with any luck, it will being a new colony.

And it is a long-lived colony. On average, Waratah Anemones live 50 years, but they can live as long as 210 years. This really is a Kingdom of Clones.

 

I was measuring urchins in a deep tunnel near the low tide, when to my shock a black tentacle wrapped around my ruler. Instinctively I tried to yank the ruler from the water. A second tentacle joined the first, pulling my hand into a shadowy crevice in the tunnel.

Laughing now, and maybe not trying as hard as I should have, I pulled back against the octopus hidden in the corner of the tunnel. It delicately reached out and gripped the ruler in a third tentacle, and plucked it cleanly from my hand.

I put my cheek against the water, hoping to catch a glimpse of the cheeky cephalopod. It had disappeared completely into the shadow of the ledge.

Amused, I stuck my head out of the tunnel. The young girl and her mother were still looking for interesting things amongst the rocks. “Did you want to meet an octopus?”

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Do you want to meet an octopus?

The young girl charged over without hesitation. I called Keen over, and asked him sweetly if he could free the urchin from the rocks in the bottom of the pool. Keen obligingly stuck his hand into the water. A moment later, he squealed. The octopus was fishing for humans!

The octopus was a Gloomy, probably a young adult, identified by the rusty orange blush on the underside of its tentacles. Octopuses (or octopodes, but never octopi) are members of the mollusc order, the same as periwinkles, oysters and limpets. Like most molluscs, they have a siphon and a tough tongue called a radula, in octopuses modified into a beak.

That is almost where the similarities end. Octopuses are as intelligent as they are alien. An octopus is a master of camouflage and imitation, a puzzle solver, an ingenious hunter and escape artist. Each of their eight arms is partly capable of autonomous action, reducing the brain work an octopus has to do to co-ordinate.

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#067 Gloomy Octopus (Octopus tetricus)

Keen had pitted himself in a battle of strength against the octopus. The Gloomy was holding fast to the side of the tunnel, three of its tentacles squeezing Keen’s wrist. As the octopus surged forward to gain ground, its elongated head and bright orange eyes peered around the tunnel mouth. Its pupil was the shape of a bowtie, set in a streak of golden orange. Strange but beautiful eyes, fixed upon these giants of the air.

My ruler dropped down into the water. It must have slipped from the octopus’s grip. The Gloomy let go of Keen. I reached into the water to retrieve the ruler and had just a glimpse of the Gloomy retreating into the darkness of the tunnel.

I sat by the water a while, and twice more the octopus returned. I made sure the rocks I’d moved were back in place, in case they had been part of the Gloomy’s home. I imagine it must have though the ruler would make a charming addition to its living room.

While it may have been defending its home, or simply getting a taste for humans, I couldn’t help but feel the octopus was playing with us. It was happy to test its strength against ours, but never went all out, just as Keen and I restrained ourselves. There was intelligence in its gaze and the purposeful way it moved, returning the second time along the roof of the tunnel, in a place we would not expect to find it.

 

Out of a seastar, an anemone and an octopus, did you know the animal most closely related to us is the seastar? Yet all of these creatures are mysterious and strange. One looks like a cookie, another is an alien intelligence, and the last, longest-lived of them all, conquers the beach with its very own Kingdom of Clones.

 

Find out more about Waratah Anemones: University of Queensland’s Fact sheet

#004 Brickyard Full of Dreams

There is a place in the north where few swimmers go, and which is inaccessible in all but the lowest tides. Its name is Brickyard Park and it is perhaps the most splendid place in all of Gong.

 

Beneath the cliff the rock ledge stretches out a hundred metres into bright, deep blue ocean. Baitweed grows on every surface, making an emerald carpet of the ledge. A smattering of rock pools reflect a sky the colour of a robin’s egg. Rather than a shelf over the ocean, the Brickyard reminds one of a meadow in the sunshine after a storm.

When the tide is at its lowest waves slop against the eroding rock at the ledge’s chin. Water rush up white and foamy up a natural gutter, and when it drains back into the ocean, tall hanks of kelp are seen pulling tight against their moorings.

The pools are deep. Young Black Drummers and Common Silversides grow fat in the autumn, waiting for winter when they will migrate to the ocean. Families of leopard-print Smooth Toadfish chase each others’ tails, while Cocos Frillgobies, Jumping Blennies and Eastern Fortescues grow impatient, waiting for the months when the pools will be peaceful once more. Anemones, Eight-Armed Seastars and Elephant Snails cluster on the shallow verges of the pools, while urchins, oysters and Warreners live ever-changing lives on the substrate.

Here and there Sooty Oyster Catchers stroll, tall black birds with blood red legs and beaks, hunting for oysters, limpets and snails. Teenagers tremble in unseasonal bikinis, daring each other to leap into the ocean. With a whoop and a splash one is gone, paddling out into the depthless blue.

To the south is one can see the city, the rolling coastline and the great green bulk of the Escarpment. Late afternoon light spirals like diamonds from the crests of waves. This place is paradise.

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Its moods change in an instant. In the rainy autumn season, the swell reaches eight feet. A fast-rising tide rushes up the gutter and fills the innumerable channels with white foam. With even an inch of water over the shelf, the Brickyard becomes dangerous, sudden deep pits and pools hidden beneath kelp to trip the unwary explorer. The shelf is swiftly cut off from the beach. A rockslip on the shelf’s corner forces wanderers out into deeper water, where an unpredictable current can rip away one’s feet.

There is no comfort even in the cliff at one’s back. Its verges are soft, prone to collapse. Rugged shrubs grasp the edge. Dozens of their number lay drying on the ledge below. Boulders the size of cars strew haphazardly at the cliff’s foot. This is not the place to be in a storm.

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Elephant Snails, Eight-Armed Seastars, urchins and limpets sunbathe in a shallow corner.

And yet the Brickyard is teeming with life. Existence here revolves around the Baitweed. Its satin emerald appearance makes Baitweed a visual pleasure, and it is soft and cushiony underfoot. It looks almost like grass spun from velvet. Baitweed can be eaten by humans, is full of nutrients and tastes good. However, humans are not the most important consumers of Baitweed. Fish, particularly Black Drummers and Ludericks, are so fond of Baitweed that they will even take it off a hook.

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#002 Baitweed (Ulva compressa)

Despite their infamy as some of Australia’s only herbivorous angling fish, in their infancy, Black Drummers are mainly carnivorous. They will eat small snails, Brine Shrimp and any stray bit of meat that happens their way. As they grow older, these fish incorporate more and more algae into their diets, until they become more herbivorous than carnivorous. It’s interesting to note that ichthyologists suggest there be no such thing as a purely herbivorous fish. When we consider land animals, we think very much in terms of “Cows are herbivores, cats are carnivores.” In truth, most animals are omnivorous, only to a greater or lesser extent. Cows and deer will supplement their diets with insects and the odd bit of meat, and “carnivores” such as dogs will happily include as much as 30% plant matter into their diets (not Salty. The closest Salty comes to a vegetable is maple-flavoured bacon.)

So while a Black Drummer starts life picking out the tiny snails and arthropods living amongst the strands of Baitweed, in later life they prefer the green algae itself.

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#115 Black Drummer (Girella elevata)

In the Brickyard, Black Drummers occupy large, deep pools, swimming in bands of three and four, generally governed by a “boss” Drummer. They are deep-bodied, strong fish. Infants are striped silver and dark grey, making them appear very much like silver striped Ludericks. As they grow older, the stripes fade, leaving Black Drummers somewhere between sandy brown, deep blue and black. They can also change colour with mood. In the Dangerpus Labs I keep three Black Drummers, Holly, Molly and Dolly. Holly is the boss and Molly is a boy. I often watch them after being fed, where Holly becomes a stormy dark grey and flashes around the tank with her dorsal spines erect and her gill coverings open. She makes her appear as big and intimidating as possible. Her sister, the docile Dolly, will become a buttery silver, keeping to herself near the bottom of the tank.

Once, when I introduced a new fish into the tank, Holly turned such a jet black that her dark grey stripes (she was quite young at the time) stood out in stark relief. She then swam slowly backwards around the new fish. It was clear to everybody that Holly was not happy.

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Keen tracks Black Drummers. Note the field of Baitweed colouring the rocks green. This entire shelf is usually submerged.

There is one more animal to keep your eye out for in Brickyard Park: the Elephant Snail (Scutus antipodes). While uncommon elsewhere, in the Brickyard Elephant Snails are in abundance.

These huge black gastropods are the largest of the false limpets, growing up to 150 mm in length. They are generally sedentary creatures, though can move quickly when disturbed. You will know one when you see one! In the Brickyard they hang around the verges of pools, in crevices otherwise populated with seastars, urchins and limpets. They are massive black blobs with two distinct antennae and a white shield-shaped shell. If you put your finger gently to the snail’s back, you can pull the black membrane right up over the shell. If you do this, there will undoubtedly be some baffled antennae-swaying on part of the snail, but they are soft and muscular and quite pleasant to stroke. If I had the strength to break their suction-grip on the rocks, I would very much like to let one crawl around my arm.

 

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#028 Elephant Snail (Scutus antipodes) … Good old Scutus. A good bloke, that Scutus.

Elephant Snails are algae feeders, but do they eat Baitweed? I don’t know. That is something I need your help to find out. Also interesting is that Baitweed is known to grow in polluted sites with high levels of nutrients, such as fertiliser runoff. This kind of pollution is always a risk near coastal towns, but the Brickyard is especially notable for its abundance of Baitweed. Is there an especial amount of runoff reaching the water from Coledale township?

Join Salty and I next time for a close encounter of the eight-legged kind as we get close and personal with a Gloomy Octopus, and I go swimming with a Wobbygong shark.

Until then, happy exploring!

 

 

A Windang Shindig

The Gong 151
#003 A Windang Shindig

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On a cool and blustery day in March, Salty, Keen Wasabi and I hiked around Lake Illawarra foreshore to the sandy arm of Windang Island. The island’s green top rises conspicuously from the lip of the lake. Anglers endure relentless plumes of spray on the seaward cliffs, each wave sending waterfalls cascading down deep flutes in the rock. Snorkelers proliferate in the summer, diving from ledges exposed at low tide, while swimmers wander up from Warilla Beach to survey the long and peaceful bay. The island is also notorious for sharks.

At 11 o’ clock the tide was at about 0.6 metres and dropping. Things that are usually submerged were becoming exposed. Keen and I dropped our nets and tanks on a rock ledge and waded out amongst the pools.

Soon we were walking on mats of Neptune’s Necklace (Hormosira banksii). This brown alga is made distinct by the string of olive-coloured beads that make up its thallus (body). Like plants, brown algae uses chlorophyll to photosynthesise and  absorb energy from the sun. Unlike plants, it also produces xanthophyll, a yellow pigment. This gives brown algae its distinct brown-green colour.

While at first it seems weird – after all, chlorophyll works perfectly well for plants – the secret of brown algae is where it exists in the ocean. Red light is bad at penetrating the ocean’s surface. Green light however penetrates deeply into the water. Because a thing’s colour is determined by the light it reflects (meaning green plants reflect green light) algae need to be differently coloured to absorb the light available to them beneath the waves. For Neptune’s Necklace, this means disguising its green chlorophyll with red pigment.

What I find fascinating about Neptune’s Necklace is just how well-equipped it is to maximise its light exposure. The alga is made up of multiple strands of beads called thalli. Each bead is made of a  spongey tissue filled with air and protected by a waxy coating. When submerged, the air makes the beads float, drawing them towards the surface, where there is more light. When the tide drops, the beads lay like a carpet across the rocks, their waxy coating preventing them from losing too much moisture.

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Shells embedded in the island’s dirt wall.

Neptune isn’t the only one who fancies his algae. As we sat by twin rock pools on the low intertidal, Keen and I counted 135 Zebra Top Snails (Austrocochlea porcata) in and around the strings of beads. Interestingly, of all the species of snail in the pools, only Zebra Tops were found on the Neptune’s Necklace. Smaller snails seemed to prefer the shelter of the algae more than the larger ones, who preferred grazing on an encrusting brown algae on the bottom of the pools.

Up until last week, I kept five Zebra Tops Snails in my laboratory aquarium. They eat the slimy brown algae that is a fact of aquarium life, and it’s fun watching a snail licking glass.

Woe betide me, this week I am down to three Zebra Tops. The reason? Clever fish. Working together, two of my fish (Holly, a Black Drummer, and Dart, a Blackspot Sergeant) repeatedly ram the Zebra Tops until they come unstuck from the glass and tumble upside-down into the sand.

Like other marine snails, Zebra Tops have a tough disc called an operculum that they can draw over the opening in their shell, like shutting a door. My fish are quite unable to get past the operculum. But, as they learned, if the snail wants to right itself, it has to push its operculum aside and stretch its soft body around the top of the shell to grab a hold of something solid. When that is done, the snail gives a quick pull and flips around upright.

Holly and Dart wait until the snail’s soft body is exposed, and attack. In just a few strikes the fish have conquered a snail as big as themselves. This bringing down of the mammoth results in tank-wide excitement, as the other drummers rush in for a nibble and the crab dances out of his cave, claws waving.

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Scary-story-snail face.

On the beach, Zebra Tops have more insidious enemies than tiny fish. Seastars prowl for young snails. You will have seen seastars sold as trinkets and jewellery. Dried and bleached, they offer poor comparison to these active hunters.

A sea star’s underside is covered in hundreds of tube feet. At the end of each arm, there is a splay of probing fingers and a rudimentary eye. A seastar can move as swiftly as a snail or abalone. It crawls over its pray, wrapping it in powerful arms. It then everts its stomach, coating its prey in digestive juices. Finally the seastar draws its stomach and its melted pray back into its body.

One such predator on Windang Island is the Eight-Armed Seastar (Meridiastra calcar.) It’s obvious when these seastars are busy eating, as their central disc will be raised into a hump, the prey engulfed beneath it. While snails are high on the menu, Eight-Armed Seastars will also graze on algae, and I have even seen them feasting on crabs’ legs and fishes’ tails.

Perhaps one reason Zebra Tops choose to hide amongst the beads of Neptune’s Necklace is that it is not readily navigated by seastars. Seastars probably also have poor vision, and cannot tell a small Zebra Top from a bead.

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Anglers enticing sharks with their juicy backsides.

“The sale of souls to gain the whole world is completely voluntary and almost unanimous…but not quite.”

As we finished counting Zebra Tops (Keen felt sorry for some and rescued them from seastars. But echinoderms need to eat too!) we noticed a huge white and grey Pelican riding thermals rising from the hot exposed rock. Wind gusted hard over the island’s top, and the Pelican would surf thermals for a minute before lowering itself into the gusts and riding in a wide crescent out over the ocean. Seeming without a care in the world, it would then coast over the island and catch another thermal.

“Do you think it’s having fun?” said Keen.

“Looks like it,” I said.

We watched the seabird, a proud example of Australian Pelican (Pelecanus conspicillatus.) Its wings wobbled as it hovered on the thermal. Then – it dropped and swooped out over the waves. In moments it was back.

“It’s not looking for food,” I said, as the seabird hung suspended in the air. “And that does look like fun.”

Keen sighed. “I wish I had wings.”

We spent a while chasing gobies in rock pools, and then we were hungry, which meant it was time to go. On the return hike to the car we walked past the mouth of Lake Illawarra. The tide was starting to rise and the foreshore was wet and dark. It also appeared to be moving.

“Hey, crabs!” I had ditched my gear and was dancing amongst crabs in a second. “Look, Keen, soldier crabs!”

All across the foreshore, an army of perhaps ten thousand soldier crabs were digging out new holes above the waterline. In amongst the waves of smaller Mictyris platycheles were large Light-Blue Soldier Crabs (Mictyris longicarpus) looking like horses amongst foot soldiers. They were oblivious to us. By the drove they kept on digging, while others processed sand through their mouthparts, restlessly surging across the boundary of surf and sand.

Salty poked his nose into a crab’s back, and watched baffled as the crab burrowed in a spiral into the wet sand. In seconds it was up again, scuttling for higher ground. From the water a Pelican watched on idly, sailing as majestically as a brilliant white yacht. Storm clouds bathed the escarpment beyond.

Keen and I finished the journey to the car in high spirits. The world can be savage, it’s true. But from the snails sampling the finest delicacies of the sea, to the pelican surveying its kingdom, it is also a world of great joy and satisfaction.

Thank you Keen and Salty for a banger of a trip out of Windang Island. Thanks to you two, I’m finally able to present the first five Gong 151 species!

 

001_Neptunes_Necklace_small

#001 Neptune’s Necklace (Hormosira banksii)

Length: Up to 300 mm

Zone: Low intertidal

Sighted: Day, on rocky substrate in pools and low-lying channels

Locations: Windang Island, common

 

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#027 Zebra Top Snail (Austrocochlea porcata)

Height: Up to 25mm

Zone: Low intertidal

Sighted: Day, on rocky substrate and algae fronds

Locations: Windang Island, common

 

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#078 Light-Blue Soldier Crab (Mictyris longicarpus)

Carapace width: Up to 25mm

Zone: Low intertidal (brackish water)

Sighted: Day, on border of sand and sea

Location: Windang Island (Lake Illawarra entrance), common

 

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#090 Eight-Armed Seastar (Meridiastra calcar)

Arm radius: Up to 50 mm

Zone: Low intertidal

Sighted: Day, on submerged rocks and rocky substrate

Locations: Windang Island, uncommon

 

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# 138 Australian Pelican (Pelecanus conspicillatus)

Wingspan: Up to 2.6 m

Zone: Shore

Sighted: Day, cruising on calm water or riding on thermals.

Locations: Windang Island, uncommon

 

Now it’s up to you. Get out into the Gong and meet some animals!

For the five species listed, we need to find:

  • Which locations they can be found
  • Their numbers in each location
  • Their interactions with other species
  • What they eat
  • What they do all day

You can join Salty and I for a day of discovering sea creatures on Saturday 8th April 2017 at Bellambi Beach. Some snacks will be provided. Bring a bottle of water, your camera, and let’s see what we find.

*Coming soon: Updated link to the 151 Field Guide*

Make Your Own Field Notebook & First Expedition

The Gong 151

#002 Make Your Own Field Notebook & First Expedition

Are you ready to get out in the field and start meeting species? Simply follow this link and you can download a full 151-entry notebook to keep on your phone, tablet or computer.

Beware, the notebook is by no means finished. There’s much to come, like an area map, a tidal zone reference, and of course the 151 species you and I are going to catch.

Updates to the notebook will be made fairly regularly. Most of these should be in the form of pages that you can copy and paste into your notebook. Of course, if you would like to add new fields to the template (such as food sources for each species) than please go ahead. Make it your own!

Below I’ve included the entry template with one species filled out. There’s also an annotated picture explaining the template in a bit more depth. Your comments and suggestions are very welcome. Also exciting – very exciting – is that one weekend in the very near future, I’ll be taking a group out observing. If the weather is warm enough, this may involve snorkelling at Bellambi Rock pools. Bellambi is brilliant for its variety of intertidal life, from brittle sea stars to elephant snails, colourful blennies, black drummers, octopuses,  crested terns and waratah anemones. A friend and I once even found a magnificent weedy seadragon washed up on the beach.

 

If you have suggestions for the field guide, or would like to join our weekend expedition, feel free to drop me a line. With your help, we’ll make the best marine field guide there ever was!

 

Sample Field Notebook Entry: 

# 051

Common name: Little Blue Periwinkle

Scientific name: Austrolittorina unifasciata

051_little_blue_periwinkle

         Kingdom       Phylum          Class                 Order                    Family             Genus

Animalia        Mollusca      Gastropoda      Caenogastropoda    Littorinoidea   Austrolittorina

 

Date observed: 19th March 2017

Time of day observed: 15.29

Size: 10 – 20 mm height; 5 – 15 mm width

Location: Thirroul Beach

Zone: Splash zone to high intertidal

Number encountered: 1000s (common)

 

Interactions within species: Little blue periwinkles follow each other to form aggregations. The trail leader will stop when “bumped” into by the snail behind. Browse for algae when submerged in pool or by tide. Sometimes cluster on top of each other in towers three or four snails high. Larger animals tend to prefer being higher in the splash zone where they are infrequently submerged.

Interactions with other species: Sometimes aggregate with pyramid periwinkles. This is more common high in the splash zone where desiccation by wind and sun is more likely. Often stepped on by people, though soft feet and flip-flops do not seem to do much damage to shells. Prayed on by crabs and birds.

Notes: Do snails show social preference, i.e. can they recognise and prefer the company of familiar snails?

What is the salt tolerance of these snails? What mechanisms do they use to rid themselves of excess salt?

 

 

Annotated Entry:

template_explanation

Remember, always carry a ruler for quick measurements. If you’re counting many small animals, like periwinkles, it can help to mark out an area about 1 metre square and count all of the periwinkles of a species in that square. That will give you a reasonable estimate of the number of animals in the area.

That link again: Downloadable Field Notebook

Good luck and happy exploring!

The Gong 151

#001 The Gong 151

Welcome to the world of marine biology!

My name is Anneque “Dangerpus” Machelle. I’m studying to become a marine biologist. This world’s oceans are inhabited by a vast array of fascinating creatures. Some are playful, others could swallow you whole. But what we know about life in the ocean is, well, just a drop in the ocean. Some biologists think over 90% of the life in the ocean remains undiscovered!

That’s why I’ve dedicated my life to studying marine life. Together with my best buddy Salty, I’m on a mission to find 151 marine species in the Gong region. Yet we can’t do it without your help. If you’ve ever dreamed of working with marine animals, discovering new species, and learning incredible things about old ones, The Gong 151 is for you. We need your help to complete this guide and become masters of the ocean.

Each week, Salty and I will explore a new species. Come with us to swim, snorkel, dive and explore to make the ultimate guide to marine life in the Gong region.

Get ready to make amazing discoveries!

For each species, hit the beach and help us find:

  • Distribution
  • Population: common, uncommon, rare or legendary
  • Size
  • Interactions within a  species
  • Interactions with other species (including humans!)
  • And lots and lots of photos

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Links:

Species discovered so far

Area map

Submit data or suggest species

Make your own field notebook DIY