Worming through the forests nets new species
Southland’s forests are full of creepy crawlies, and now a velvet worm that eats prey many times larger than itself has been found in the region.
The peripatoides taitonga, which falls under the phylum Onychophora species, also known as velvet worms, was found by researchers from Massey University in Croydon Bush, Seaward Downs and Waipori.
A phylum is a scientific term grouping together related organisms on the basis of their fundamental characteristics. Soft-bodied, multi-legged invertebrates, they were found in the forest under rocks, around clay banks, and where the vegetation had not been disturbed, Massey University Professor of Evolutionary Ecology Steven Trewick said.
Despite the recent finding, the phylum Onychophora had an ancestry dating back at least 550 million years.
“We know that from early fossils from the northern hemisphere, which is interesting, because these animals don't live in the northern hemisphere now,” he said.
While these colourful creatures were attractive to the human eye, their prey experienced a painful death.
The worm shot out a sticky juice – a “protein glue” that snared its prey which included weta, cockroaches and spiders – before using long fangs to pierce the prey and dissolve the body contents.
“The more the prey struggles, the more it gets stuck to itself,” he said.
“Even big spiders and cockroaches can be taken down by velvet worms.
‘‘Once they’re stuck to themselves, the velvet worm goes out and uses its fangs to cut a hole and then puts enzyme saliva into the prey and dissolves out the insides.
“All that’s left is the crunchy skeleton of that animal that it's eaten. So although
it’s a soft bodied animal, it’s got this fantastic technique that is unique to this group of animals that allows them to tackle all sorts of big prey.
“They’re not fussy, they will eat introduced insects just as much as native insects.”
The worms were “active hunters” who hunted underground, in holes in logs and trees, basically anywhere they could hunt during the night. They were “rarely seen” because of their nocturnal nature, Trewick said. There were big gaps in researchers’ knowledge. They do not know the worm’s lifespan or how many offspring it typically produced.
But they were born at about 6-7mm long, “which is quite big”. The way they were incubated would not make it a “high reproducing species”, and it would likely be vulnerable in terms of changes to predation, he said.
The finding of the worms had been a long-term project, with Trewick’s first paper about them being published in 1998.
Velvet worms had been found in New Zealand as early as the 1870s, he said, and the worms have been discovered at sites in Dunedin, Nelson and Wellington. They were first named peripatoides novaezealandiae or ngaokeoke, after the country.
“Since then, we’ve shown that that species is many species. They look quite similar to each other as far as humans are concerned.”
Trewick was thankful for New Zealand photographer Rod Morris’ help in finding the worms.