When we think of native plants and animals, it is invariably the large species that spring to mind first. And these days, with our increased awareness of the havoc wrought by human activity on nature’s domain, our second thought will be for conservation. Few of us can be unaware that many of the birds which in prehuman times fluttered or strutted about Aotearoa have become extinct in the past 500 or so years.
Then there are the whales, hunted to the brink of extinction over the past two centuries to oil the wheels of commerce. In this country, marine mammals and birds are at the heart of our conservation concerns.
Descending a branch or two down the phylogenetic tree, a few lizards and frogs kept the birds company on the road to oblivion, but, perhaps surprisingly, not a lot else has become extinct that we know of.
The truth is that recent extinctions have afflicted mainly larger species, while the vast bulk of our biodiversity resides with more primitive and smaller organisms—the fungi, plants, bacteria and invertebrates that still populate our forests, fields and waters.
Compared with the 230-240 species of birds still inhabiting these islands, there are estimated to be 20,000 species of fungi in New Zealand. Of these, no more than 4500 species are even slightly known. It is estimated that 90 per cent of New Zealand’s 2500 species of vascular plants depend on fungi for their existence, the plants’ roots forming beneficial symbiotic associations with the fungal mycelium.
About 20 per cent of fungi form lichens—fungi with algae living within their tissues. At an estimated 1500 species, our lichen flora is rich by world standards.
Thirty-four of Earth’s 35 animal phyla are invertebrates. Largest among them in terms of species numbers is the Arthropoda, consisting of four main groups: myriapods (centipedes and millipedes), arachnids (spiders, mites and scorpions), insects and crustaceans. Some 10,000 insect species have been described from New Zealand, but the true tally of our insect species is likely to be closer to 20,000. As many as 600 species of millipedes may exist here, and 2600 species of spider are so far known from our islands, with more awaiting description—an unusual wealth compared with many other parts of the world.
We are also rich in flatworms, with probably 200 local species. (By comparison, Europe has six species.) Land snails, too, are a major group in the forests of New Zealand. Those species large enough to make a decent morsel for a rat or pig have been sharply curtailed in range, but rarely completely exterminated, while there could be 600 or more tiny species, often occupying very localised areas.
Then there are roundworms (nematodes), regular worms (annelids) and countless groups of minute or aquatic species such as tardigrads.
With large organisms it is feasible to take measures to protect or enhance the survival of a single species (such as the stitchbird, reported on elsewhere in this issue), but as species diminish in size, this approach becomes less practical, hence the value of protecting habitats by setting aside parks and reserves. Although we often still think of these as habitats for large species, their real value lies in their significance to the many small and little appreciated species that make up most of our biota.
Given that we probably possess well over 50,000 terrestrial species in New Zealand, most of them little known, the 15 species shown in this sampling of images, captured by photographer Rod Morris’s perceptive lens, can give only the barest of glimpses into the microcosmos that surrounds us.