Fabulous Flatworms

Australian flatworm

One of the common animals in my yard and garden is the flatworm. Strictly speaking, “the” flatworm here in New Zealand is actually multiple species—possibly up to a hundred—but they have been poorly studied, so it’s unclear just how many species there are.

Flatworms are some of the most impressive predators in the garden, able to consume prey up to 55 times their own size. That’s the equivalent of your house cat taking down a female elk. They eat snails, slugs, and earthworms, digesting them externally before sucking them up with one or more mouths located midway along their bodies.

I love to find flatworms around the yard. They come in striking colours, and some have lovely brown stripes—the orange Australian flatworm (Australoplana sanguinea) is most common in my garden, followed by the relatively nondescript brown New Zealand flatworm (Arthurdendyus triangulatus). Like the slugs they eat, they prefer damp places, and they protect themselves with a layer of mucous. Flatworm mucus is stickier than slug mucous, and they use it to attach themselves to their prey during feeding.

New Zealand is full of non-native invasive organisms, but New Zealand flatworms are one of the few organisms that have turned the tables and become pests overseas. They are easily transported in potted plants, and have successfully invaded Ireland and Scotland. Though there was widespread panic at first about their potential to threaten the local ecology, they appear to have caused little damage to earthworm populations in the UK. Like most cold-blooded animals, their appetites are small. Far from being a devouring hoard, each flatworm can manage, on average, just one earthworm per week. And if they don’t manage to find an earthworm every week, it’s not a problem—they can go a year without eating.

Smells Like Spring

I know, technically it’s still winter. We’re still likely to have icky, cold, wet weather. There will be ice on the water troughs, and frost on the grass in the mornings. There are still plenty of weeks left in the skiing season. And I won’t even think about planting anything out in the garden for at least six weeks.

But yesterday smelled like spring.

That heady combination of lanolin, damp soil, and cut grass.

It sounded like spring, too, with magpies warbling in the trees, swallows chittering overhead, and lambs bawling in the paddocks.

It is not spring. Not yet. But the days are lengthening and the first daffodils are beginning to bloom. It’s time to finish all those indoor winter projects. Spring is on its way.

To the Beach

While all you folks in the Northern Hemisphere are flocking to be beach for a swim and some sun and sand, we are shivering down here in the dark days of winter. But that doesn’t mean we don’t go to the beach.

Research from England has found that people living by the coast have better physical and mental health than those living inland. I can certainly understand that.

Growing up three hours’ drive from the beach, I visited the ocean about once a year. My husband, raised in the midwestern US, doesn’t remember seeing the ocean until age twelve or thirteen.

Today, we live a mere four kilometres from the beach. When the wind is calm, we can hear the surf. When the wind is high, we can smell the sea. Even without research to back us up, we’ve learned to head to the beach when we’re stressed.

Our beach isn’t a white-sand swimming beach—it’s made of cobbles, and the waves pound viciously on the shore. It’s not a place to swim, nor really a place to sit for very long (those rocks get uncomfortable fast). It’s a place to walk. A place to search for wave-polished rocks in glittering colours. A place to watch sea birds, dolphins, and the occasional seal. A place to leave all the stress of daily life behind (I challenge anyone to remain stressed while watching dolphins cavorting in the waves).

Researchers point to the calming blue colour, the hypnotic sound of waves, and the cultural context of the beach to explain its calming effect. But for me its influence is more profound. Our beach is usually free of other people—on a busy day you might see four others. From the beach, it is difficult to see any sign of humans at all—the odd bit of flotsam, but not even much of that. On our beach, the world is reduced to sky, water, and rock, shared only with wildlife. It’s easy to imagine the world is in better shape than it is. It’s easy to believe the vast ocean will endure, in spite of human stupidity. It’s easy to think those rare Hector’s dolphins, which we see nearly every time we visit the beach, are actually common. For the space of time we inhabit the beach, all is right in the world.

It doesn’t last, of course, but it’s good to have that escape so close at hand.

Beautiful Brawny Barnacles

My daughter and I went for a walk on the beach after school yesterday. It was chilly, but calm, with a clear mid-winter sky and dolphins in the surf.

Washed up on the beach was a large tree stump crusted with barnacles whose colours mirrored the evening sky. The size and profusion of barnacles indicate the tree was lodged in the water for a long time before it was hurled onto our beach.

Barnacles are strange creatures. They’re crustaceans—kin to crabs, shrimp, and lobsters—but they don’t look anything like their relatives. Barnacles have given up the ability to move on their own (after a brief mobile larval stage), and instead settle down in places where the water moves around them—intertidal zones, the backs of whales and the bottoms of ships are popular barnacle real estate. Instead of having to wander in search of food, moving water carries lunch to the barnacles, and they filter it out of the water with feathery appendages called cirri.

Staying put in places where waves pound day in and day out isn’t easy. Barnacles produce a ‘glue’ that’s one of the strongest natural adhesives around. With a tensile strength of 35 N/mm2 (5000 psi), it rivals the best commercial epoxies. In a strange quirk of biology, the glue is produced by a gland at the base of the barnacle’s antennae, and so the animal is glued head-first to the substrate. Once glued to its home, the barnacle forms a ring of plates around its body to protect it (this is all that is left of the barnacles pictured here—the animals themselves have died).

There are costs to gluing oneself in place. Unlike other sessile animals like corals who release their eggs and sperm into the water for fertilisation, most barnacles rely on internal fertilisation. To reach their neighbours and manage this feat, the hermaphroditic (both male and female) animals have penises that can be 8 times the length of their bodies. Until recently, researchers thought this was the only way barnacles could reproduce, but in 2013, a study found that at least one species of barnacle (with a particularly short penis) can capture sperm from the water if it’s too far from its neighbours.

Barnacles are of human importance. They encrust ships, leading to increased drag and fuel costs. But their habit of attaching themselves to all sorts of debris can also be used forensically to track marine wildlife like whales and turtles, items from shipwrecks and airplane crashes, and marine debris. Additionally, barnacles are considered culinary delicacies in Spain, Portugal and Chile.

Beautiful and brawny, weird and wonderful, barnacles always make me smile.

Backyard Biodiversity

Craterium minutum

I know it’s been a good weekend when I arrive in my office Monday morning to find my microscope in the middle of the desk, and dirt and bits of plant material strewn about.

It means I’ve been outdoors, seeing cool stuff, identifying plants, insects, or other organisms.

Once you start looking at and identifying what lives around you, the variety is astounding. A glance at the citizen science website iNaturalist shows a pile-up of dozens of observations at our address—and those are only the species we’ve bothered to upload.  I’ve identified 58 species of weeds in the vegetable garden alone. We have half a dozen slime moulds, dozens of fungi and lichens, who knows how many insects and other invertebrates. Then, of course, there are the birds, rats, mice, stoats and other vertebrates. I’ve never bothered to make lists of anything beyond the weeds.

So here in the dark depths of winter, I’ve decided to start a comprehensive list of the biodiversity on our little acre and a half. It will take time. It will require my microscope and many Monday mornings brushing dirt off my desk. But wouldn’t it be cool to know exactly how many other species we share this patch with?

And though many of the species I’ll put on my list are ones I’ve noted many times before, I’m sure some will be new and surprising, like the beautiful slime mould, Craterium minutum my daughter found last week.

Because, the truth is, we needn’t travel far to find natural wonders. We merely need to look closely and have a sense of wonder.

Here Comes the Sun

After weeks of grey, unending drizzle, we’re finally seeing a bit of sun. Mushrooms abound in the yard, revelling in the dank mist we’ve been swimming through for a fortnight. We are all eagerly awaiting passing of the solstice and the lengthening of the days.

Though it is still pretty dark and drear, and the days will still be short for some time, there are signs of the spring to come.

Lambing has started. This is the time of year when the neighbours grow noisy, with lambs and ewes calling to one another day and night.

The preying mantids are gone, but their egg cases are dotted around the yard, promising a healthy population of my favourite predators come spring.

The daffodils and snowdrops are coming up, and I’ve even seen them blooming in other people’s yards.

And tomorrow is the solstice. Friday, the sun will remain above the horizon fractionally longer than it did the previous day. We’ll be on the upswing.

Beautiful Basket Fungus

Mature fruiting body

One of my favourite fungi is Ileodictyon cibarium, the basket fungus, native to Australia, New Zealand and Chile. We have been treated this year to an amazing display of these fungi in our recently wood-chipped pond garden. Usually we don’t notice them until the fruiting bodies are fully formed, but because there are so many this year, we’ve been able to watch their whole emergence, from egg-like volva to lacy soccer ball.

Aside from their striking look, there’s nothing particularly lovely about these fungi. The basket fungus is in the family Phallaceae, also known as the stinkhorn fungi. Members of this family—you guessed it—have a foul odour (and many are phallus-shaped). The carrion or dung-smelling fruiting bodies attract flies to disperse the spores. Supposedly, the young fruiting bodies are edible … but not very tasty, as you can imagine.

Immature volvae

In spite of their smell, basket fungi have a certain celebrity status, owing to their remarkable structure. In fact, in Hagley Park in Christchurch there used to be a play structure in the shape of a giant basket fungus. I’m not sure if it’s still there—my kids don’t frequent playgrounds anymore—but it was always a favourite with my kids.