“It’s worse than that, it’s dead, Jim”

That’s what ran through my head on seeing this sea urchin in a rock pool at Flat Rock, Ballina, yesterday (why I was thinking of Star Trek, I’ll never know). Its green tube feet were moving quickly, but it wasn’t going anywhere. The orange spines were also moving and it would normally be speeding (if you can call it that) across the sandy rock pool bottom on the tube feet. But this one had met its demise. What it had left for a nervous system was causing the movement –  if you want to know more about what’s inside, go here.

The underside shows, in the centre, the mouthpiece (called the Aristotle’s lantern), which it would have used to scrape algae off the rocks and move it inside the body for digestion.

This one had been thoroughly speared and its guts eaten by a bird, possibly one of the sooty oystercatchers or the eastern reef heron (Egretta sacra albolineatai, dark morph) that was poking its beak into the pools.

Various migratory birds were enjoying a rest or gleaning. They’ll be off to the northern hemisphere in autumn.

There was also a small octopus on its last legs, so to speak, looking very unhealthy in one of the pools. It was upside down, flailing its arms and couldn’t right itself, and when I carefully moved it right-side-up, it didn’t trundle off to shelter like they usually do. Perhaps it was at the end of its life – octopuses often last only a year or so.

All in all, a bit of drama on the rock platform in the hot summer sun.

On the rocks

Rock walls are harsh environments. The sun beats down, the rain pelts down, the wind blasts through and over the rocks and, at the North Wall at Ballina, the river and ocean waters take turns, depending on the tide, to deliver spray. It’s hot, cold, wet, dry, salty and fresh, sometimes in short order and over and over again. You have to be a tough, resilient animal or plant to live there.

The North Wall is an artificial wall, built from 1889-1912 along with the South Wall. It was planned to stabilise the mouth of the Richmond River and help provide safe passage for ships from Sydney (and other east coast ports) that were transporting people and goods to Ballina. From there, smaller boats shunted back and forth to Lismore and small towns in between. Rileys Hill quarry down south provided the rocks, which were brought up the coast by barge. Prior to the walls being built, the mouth of the river moved over time and so did the sandbars, which were dangerous to shipping. It’s still a dangerous bar with fast-flowing water.

In 2016, structural repairs were carried out in the form of hanbars. Like many, I thought these blocks were very ugly, until Cape Town friend Jane pointed out that the structures are somewhat similar to the dolosse concrete blocks invented in South Africa, based on a kind of traditional knucklebone game. After that, I felt they looked more interesting.

View of the cyclone-tossed sea from North Wall, Ballina – hanbars and Rileys Hill quarry rocks in the foreground

The path on the wall is popular for walking, jogging, cycling and pooch walking. It also gives great views of the beaches to the north and south, of breaching whales while they are migrating up and down the east coast, and of pods of dolphins exploring the waters for a feed. In a decent storm, there’s almost nobody there and the waves are spectacular.

One of the tough animals commonly spotted is the eastern water dragon (Intellagama lesueurii). You might see a dozen of these, of all sizes, on a 10-minute amble along the wall, sunning themselves. They can grow up to 90 cm long (nose tip to very-long-tail tip). They eat small reptiles, worms, frogs, insects, vegetation, fruit, small mammals and molluscs, all of which would be available in rock crevices or on the nearby sand dunes.

The skin texture is marvellous – Andrew took some close-ups of some medium-sized ones yesterday.

We were able to see another tough reptile living on the wall – a carpet python (Morelia spilota). We’d only seen this one once before, last week. I guess it was warming up. They usually feed at night, on rats, possums and birds – and maybe small lizards?

The python would have been as long as I am tall – and very healthy looking.

Meanwhile north of the wall on the windy Lighthouse Beach, a willy wagtail (Rhipidura leucophrys) was following us, possibly watching out for any insects we might dislodge as we picked up plastic from the tide wrack – not much, thankfully.

The cyclonic seas had washed up the usual suspects that often come in from far offshore together – glaucus, porpita and bluebottles. The only thing missing was velella.

You really want to avoid the ‘pearls of pain’ – nematocysts – of the bluebottle, even on the sand. They can still be triggered by contact with your skin.

You never know what you’ll find on a walk on the wild side.