Creature Comforts: Blind Velvet Worm

Blind velvet worm illustration on pink background

Homes are getting few and far between down here. My friends and I have trouble finding decent leaf piles or decayed logs to hole up in. When will this housing crisis end? 
L. anophthalmus. Mt Allen, Tasmania 

    Hello, L.  

    It seems you are a blind velvet worm living in Tassie’s northeast marshes. Logging is the problem here—to access trees marked for timber, gargantuan machinery must be hauled through. Whatever hasn’t already been removed for their safe passage is crushed under their tread. The homes you’re looking for—rotting logs, decomposing leaf litter, and loose, moist soil—are either collected or cleared, taken clean off the map.

    When is a worm not a worm? 

    When it’s an onychophoran, of course! Segmented, soft-bodied, legged ‘worms’, onychophorans—common name velvet worm—are some of the world’s oldest creepy crawlies, with an evolutionary history hundreds of millions of years in the making.

    As the only remaining organisms in their phylum, velvet worms are most closely related to the Arthropoda (think spiders, shrimp and centipedes) and Tardigrada (water bears!) phyla. Velvet worms can belong to either the Peripatidae or Peripatopsidae families, but to be the only type of organism within their phylum is highly unusual—most species have many taxonomic mates throughout the ranks shown below.

    Though hundreds of species of velvet worm are found across the globe, Australia boasts the highest number at 74—and it’s rising. They’re possibly our most interesting and most ignored animal. Velvet worms have quietly churned away in our soil, occupying moist ecosystems as the predator of small invertebrates and keeping crunchier insect cousins in check for millennia.  

    To say that velvet worms are simple would be a lie. They don’t only do worm things. For starters, they’re active predators. Velvet worms use a pair of modified front legs to shoot sticky mucus—lethal silly string—at their prey, immobilising them like some kind of many-legged Spider-man. Once they’ve descended, velvet worms then slice a hole in the side of the insect they’ve caught, liquefy its insides with toxic saliva and hoover out the tasty mush. Some of their more redeeming qualities include sleeping in piles and sharing the plural noun ‘cuddle’.   

    Varying widely in appearance, Australian velvet worms tend to be dark brown or blue, with diamond-like spots, and between 14 and 16 pairs of legs (international worms may have up to 43 pairs!). These stumpy legs have no bones or exoskeleton to bend, but rather subtle muscles which cause them to contract and extend, altering the fluid pressure in the body as they go and creating the classic inchworm-like flowing movement.  

    First discovered in the 1820s, their name comes from the velveteen texture of their skin. Of course, the first thing to do with a newly discovered species is to reach out and prod the poor thing (not recommended!). Velvet worms are covered in papillae, which are tastebud-like protrusions that are integral to the worms’ mechanical and chemical perception of their environment and dutifully carry information through sensory nerves to their central nervous system. Without these, velvet worms—which have barely-functional eyes at best—wouldn’t be able to navigate themselves to the damp, dark hideouts that protect them.  

    These habitats don’t only serve as protection from their predators though—they serve as a stronghold against the elements. Sunlight and air are their kryptonite.  

    Similar to frogs, velvet worms experience gas exchange across their thin skin, accepting oxygen and releasing carbon dioxide in a process of simple diffusion. The process is passive and non-autonomous; molecules spread from spaces of abundance to spaces of deficit (oxygen moves from the air into the worm, carbon dioxide moves from the worm into the air). But water is a molecule capable of passing through the skin, too.  

    If the air is dry enough—if it becomes a space of considerable deficit—water begins to move away from the body and into the atmosphere, sapping moisture from the worm and slowing its internal systems. And that’s not all. Only some gas exchange happens via velvet worms’ skin. Most oxygen finds its way in through tracheae. These are specialty-built, 0.3 millimeter-wide tunnels that provide an unimpeded pathway from the surface of the skin to the internal organs. Kind of like an oxygen highway.  

    But where oxygen can move, so can water. Other worm-like organisms and insects tend to have one pair of them per body segment, for a total of loosely fifty tracheae. Velvet worms have around seventy tracheae per segment, for a total in the high hundreds. As permanent fixtures that cannot be closed, these tracheae can inadvertently facilitate catastrophic moisture loss. If forced into a dry environment for long enough, velvet worms will die of dehydration.

    The environmental threats making the rounds—deforestation, agriculture, pollution—cannot be resolved simply, or reversed simply. Logging doesn’t just bulldoze habitats or decapitate velvet worms; it forces them to slowly and painfully relocate through deadly conditions to new safe havens, which become more and more scarce as time goes by. Few worms will be able to avoid dry air on their way, and even fewer of them will succeed in finding a new home.  

    So, dear L, 

    Things are dire. The housing crisis might not be a crisis anymore. It might be the new norm. There is some evaluation being done, and some advice being thrown around, but there is yet to be any change. I’m sorry to say that you and your friends are endangered.

    Sophie Tomassen is a third-year creative writing and screenwriting student at QUT. Her favourite unquantifiable things are natural biology, the type of love only found in animated films, and the feeling of closing hundreds of browser tabs. She writes about the small, beautiful magic we see in our everyday lives and how it can change the way we love. When she’s not writing—which is terribly often—she can be found harassing stray cats or wasting time on the endless uni commute.

    Sophie Tomassen
    Sophie Tomassen
    Articles: 2

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