An artificial environment in a museum is a chance for science to learn more about the cave weta, writes Lee Matthews.
Baby cave weta have hatched and are thriving in captivity at Palmerston North's Te Manawa science centre.
Believed to be the first time a public institution has reared Pachyrhamma edwardsii right through its life cycle - a dozen juveniles and adults established, successful mating resulting in viable eggs that hatched with baby weta now into their third or fourth moults or instars - Te Manawa live exhibits officers Erica Prier and Angela Fox are the proud weta midwives.
They're also experienced weta spotters, an essential skill during the babies' first-ever press conference with the Manawatu Standard. Nocturnal baby cave weta are shy little numbers; they hate light and sound, and they could give sprint lessons to a cheetah. Their best line of defence is to ping away into the dark on their springy, ballerina-like legs.
"We're looking for little orange dots, brown and orange dots," says Prier, screwing up her eyes, peering into the night-lit glass case. "There!"
Hugely enlarged photos of the babies will later reveal that their grain of rice-sized bodies are mottled in light orange, brown, and beige, and their long, slender, elegant legs are showing the beginning of the colouration adults carry - fawn, cream, and matt black stripes.
Ping! The baby weta's had enough. One moment it was there, clinging to the enclosure's roof with the pairs of tiny hooks on each of its six feet. The next moment it's gone. Vamoosed. No interest whatsoever in giving an interview.
Prier and Fox lament that so little is known about cave weta. Their observations are adding to the body of knowledge, however.
They first noticed the adults mating in May 2011, a month after they moved in. Their observations were a first; cave weta sex had been an unrecorded mystery.
Turns out it's a precarious-looking manoeuvre requiring Karma Sutra-like positioning. Women superior, naturally, and the males scooch underneath. Weta have cerci, prong-like protuberances on their lower abdomens, and the females' long ovipositors are between the cerci. The males nudge their way into position. After copulation, the females groom their ovipositors and antennae.
Exactly how long the eggs gestate is unknown. Prier and Fox first saw the fertile females laying eggs in August 2011, inserting their ovipositors into soft moist peat and leaf litter. They don't know, however, if those were the same females they saw mating in April, or whether this was the first time they'd laid eggs since mating.
What the eggs look like and how long they take to hatch are also mysteries. Other weta species' eggs are black, cigar-shaped, and about the size of a short grain of rice. Also unknown is how many eggs a female lays, over what time period, and how many times weta must mate to produce eggs.
They don't know if the August 2011's eggs are the ones that hatched.
They spotted the very first of the seven confirmed babies (there may be more, as yet undiscovered) clinging to rocks two months ago - a visual feat in itself.
The weta enclosure is kept at a summery 17 degrees Celsius - a cave would be between 10C and 14C - and humidity ranges between 60 and 80 per cent. The warmer climate behind the glass might be affecting breeding, growth, and longevity, but not enough is known about the species yet to know how.
Babies and adults eat much the same things; vegetation and meat, algae and fungi. In captivity, they're on mixed vege, meal worms, the odd slice of gourmet beef sausage, fruit, and they browse the leaf litter and rocks for whatever's growing. In the wild, cave weta scavenge dead birds and insects as well as eating vegetation.
"There's so much we don't know yet. We'll keep watching, and Massey's [university] has got some research money to look into it all a bit more," Prier says.
The baby weta aren't saying much. They've reluctantly agreed to photographs, no posing, just action shots captured by Manawatu Standard chief photographer Robert Kitchin's super-fast reflexes. It's time to find somebody who speaks weta, who knows a great deal about Rhaphidophoridae, or cave weta.
Massey University Institute of Natural Resources ecology group evolutionary biologist Dr Steve Trewick's the man. His office is the usual November exam-marking paperwork prang of all academics, and there's a sleeping bag lurking under his spare chair. For quick naps during all-night research projects? No, it's a leftover from tramping trips to collect insects from the bush. Trewick collected Te Manawa's first dozen cave weta from a limestone cave somewhere in the wilds of Pohangina, and advised Te Manawa on habitat.
He's approving Kitchin's baby photos. Not Anne Geddis-cuddly, but sharp with good all-round views of the weta. And just as all human babies look alike to the uninitiated, it seems even specialists find it devilishly hard to distinguish between nymphs of different weta species. They get more adult characteristics with every moult, literally growing out of their skins, shedding and eating them for nutrients. Moulting's dangerous for a weta. It takes a couple of days for their external cuticle to reharden, so they hide from predators.
"Well, we all like to change our trousers in privacy," Trewick says. "I'd say this little fellow's in his second or third instar [moult]. I'd hazard he's male, but at this stage of development the female's ovipositors are extremely small. Probably another eight or nine instars to go before we can tell for sure."
The weta's antennae are its most obvious sensory organ, but it's not clear what it uses to detect the crazily complex world of scent pheromones. The antennae are at least four times as long as the weta's body and legs, and are covered with tiny hairs sensitive to air movement. They use them as a blind man's cane, but the antennae collect huge amounts of sensory data.
"They're nocturnal, look at those huge eyes. They do use low levels of light when they're out of the cave and foraging."
Cave weta don't have ears. Tree weta have tympanic membranes near their front knees, but their cave cousins sense sound some other way.
"More research needed."
What's not helping is the muddle that's been made of weta taxonomy. Species have been classified willy-nilly since explorers first found the insects in the 1800s, and some of the data's been missed, doubled up and fouled up.
Massey's making a start on sorting out this confusion. It's believed there are about 50 species of cave weta, but nobody knows for sure because molecular-level study that provides DNA proof hasn't been possible until relatively recently.
"The problem is the taxonomy is so bad. The naming system has been inconsistent. It's almost worse than starting from scratch; we have to go through and rework it, reconciling all the known data . . . following the protocols for rewriting taxonomy," Trewick says.
The ecology group's building a website - evolves.massey.ac.nz/Betawetageta.htm - to develop a taxonomy, systematics and biodiversity resource for New Zealand weta, to provide resources on Rhaphidophoridaea. An $80,000 Conservation Department research grant is funding the staff and student work - although there's a welcome place for interested amateurs finding weta.
The group welcomes weta sightings and dead weta to study. (Freeze specimens and contact Trewick.) Crucial information is where the weta was found or photographed; today's smartphone GPS technology helps here.
"We hope to get the website to the point where people can go to it, find what they've seen and learn more about it."
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