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Years ago The Ranger was being trained to be a zoologist. No, it’s nothing to do with zoos. The students were gradually marched through all the different phyla of living things, and occasionally got to draw one, and even more occasionally got to cut up a dead one in formalin. With the benefit of hindsight, readers will be able to conclude that The Ranger did not go on to become a zoologist or other scientist – this laboratory life did not please him. All he really wanted to learn about was his beloved spiders, and they got about 3 hours sometime in the middle of the second year. But it wasn’t all bad news. One of the by-products of this very thorough grounding in obscure invertebrate phyla was the discovery of an entirely new group of animals – those animals created specifically to illustrate some useful zoological point. Such an animal was the proto-chordate amphioxus, another was the neotenous salamander, axolotl. If you’ve heard of either of these creatures before, The Ranger will wager that it was during a biology lesson of some sort. A prime member of that exclusive set of illustrative animals was the velvet worm, Peripatus. A bizarre intermediate between annelid worms and the jointed arthropods such as insects and crabs, this animal looks like nothing more than a great big caterpillar. It is a member of the phylum Onychophora, the velvet worms, also known as spitting worms and walking worms, all three of which describe well some unusual characteristics of these odd animals.
All The Ranger used to know about onychophorans was that they looked a bit like caterpillars. Zoology training didn’t extend to finding out much about what these creatures actually did. But, my, how much more interested we all would have been if it had – these worms are pretty bizarre! Onychophora live in groups, defend territories and subdue their prey with sticky goo. Research at the University of Arizona now suggests that the worms are more closely related to spiders than anything else. Attracted by the spider connection, when The Ranger was reading about this he was intrigued by the comments of Prof Nicholas J. Strausfeld of The University of Arizona:
“The animal looks simple, but the brain is not simple. Onychophora have pretty complicated behaviors. Colleagues in Australia have discovered that they have fascinating rivalry behaviors, interesting group behaviors and group interactions. Their ecology and genetics are fascinating, and they have really weird sex.”
Really weird sex? Tell us more! But tantalisingly, Professor Strausfeld does not tell us more. A good scouring of the web later, and a few clues emerge. A tease from this German original article translated by machine into English:
As previously mentioned comes within the kind Paraperipatus a penisartige structure forwards, however yet in function to be observed could not, while with many Australian kinds with the males special structures at the head exist, those the sperm cells transfer to likewise serve seem.
Transferring sperm with their heads? Yes, that’s a bit curious. But we’re all grown-ups here, surely there’s better than that. Wait – what’s this?
…the male in the diameter about a sperm cells package at the flanks or on the back of the female, large, puts down a millimeter. Special one Amoebozyten cells mentioned, in the blood of the female are contained, separate thereupon enzymes off, aimed the skin underneath the sperm cells package and at the same time its covering dissolve. As consequence sperm cellses by these arrive produced “wound” into the body concavity of the female and penetrate from this from to the ovaries, their wall it penetrieren. In this way they arrive at the Eizellen, to be now fertilized can.
Now that does sound weird. But does it really mean what it seems to say? Sperm burns its way into the female? Is this an artifact of translation? Apparently not – the English Wikipedia says this, which is more comprehensible but infinitely duller:
Velvet worms have an unusual method of transferring sperm. The male onychophore attaches a sperm packet to the female. They tend to be fairly indiscriminate where on the female they attach the packet. The tissue beneath the packet dissolves and the packet melts into the female’s body.
Yeah, it’s confirmed as weird. What must it feel like? The worms seem to like it, as our German text goes on about a different onychophoran species:
Both animals are so firmly connected in this mating position, that even the handling did not lead by the examining scientists to a task of the mating position.
The Ranger is delighted to have at last gained a tiny insight into the crazy sex life of the creatures he half-heartedly drew all those years ago in a dusty laboratory. These colourful, lively, bizarre, animals are unphased by the examining scientists – and no doubt, if they knew a few of the curious habits of our species, the worms themselves would shudder and waggle their own stumpy little legs in disapproval. On reflection, how weird we all are.