Velvet Worm, Peripatidae sp., La Isla Escondida, Colombia
During moth night 1 at La Isla Escondida our guides kept bringing frogs whilst we were very occupied photographing hundreds of moths so we got into the habit of quickly photographing the frog so that we could continue mothing. On this absurdly productive night, this slipped in. Clearly not a frog, yet we treated it with just as much haste. I'm still glad we at least captured it as for us personally, it's an entirely new category never seen or photographed before.
Everybody keeps telling me how special they are so I did some reading, hereby a dumbed down list of cool facts about velvet worms based on my limited understanding of them:
1. They are named velvet worms because of their skin, which has microscopic protrusions and bristles giving it a velvet look. A velvet worm needs to be constantly hydrated as it will lose 1/3 of its body weight in a matter of hours during drought. That's why it usually found in the tropics, on wet soil. It has no exoskeleton. It's skin is so thin (1 micrometer) that it traps a layer of air, which rejects water. A Velvet Worm therefore is always dry on the outside.
2. They have a unique method to hunt to compensate for their slow pace: they fire glue strings at targets. The substance only becomes glue when it is in contact with air, therefore the Velvet Worm is immune to it. Even if it would hit itself, it slides right of due to its unique (yet vulnerable) skin. Range of the shot is 30-50cm. The glue spreads like a net, therefore a precise aim is not needed. If it's a hit, the victom is immobilized. It will then be opened using the mouth parts, injected with a digestive protein to dissolve the insides, and then sucked dry. It's a good thing that it doesn't need to aim well, because it doesn't aim at all. There's no muscles to give the shot direction, direction is random as the fluid moves through the body of the Velvet Worm, creating waves of glue that could go in any direction.
3. Their legs are not real legs, they are pseudo-legs which lack joints sometimes called balloon legs. They are appendages without any fixed structure and flexibly move in any direction and can even change shape. At the end of each leg is a retractable claw, only used for uneven terrain.
4. The first velvet worm known lived 540 million years ago, and they have hardly changed during that half a billion years.
5. They are not insects, and also not arthropods. Scientists have been considering velvet worms to be the missing link between worms living in the sea, and current insects. Strangely, science does not know the ancestor to insects, as the first insects known to science were already fully developed with wings. Some transitional ancestor must have existed before that, and velvet worms can be an answer. Current insights dismiss the velvet worm to be the missing link, instead it is considered a Panarthropoda, a suggested clade to group Velvet Worms, Tardigrades and all Arthropods. With Velvet Worms and Tardigrades of course being the crazy weird animals.
6. Some Velvet Worms have highly unusual reproductive strategies where the male seemingly randomly deposits his spermatophore on the female's body, which will then locally dissolve the skin to absorb it, and allow it to pass to her ovaries. This asexual reproduction happens based on chance, a male will equally deposit his stuff on juveniles or other males.
7. There are about 200 modern species known, divided into Peripatidae (Central America and Northern South America) and Peripatopsidae (Australia, New Zealand)
8. Other than a host of unique features, it's easy to distinguish from a worm for having antennae. Antennae that are thick, because they evolved from their first pair of legs. The antennae are critical to detect prey from enemies. Their second pair of legs have evolved as well, into mouth parts. And their third pair of legs have evolved into parts that shoot the silk!
9. Velvet worm eyes are single lens, not composite, and only function to see radical differences in light in order to see the difference between day and night.
10. Most Velvet Worms are loners, but there's one known social species: Euperipatoides rowelli. They hunt in packs, which means a glue party!
So yes, I suppose we could call them very special. We're basically looking at life from half a billion years ago.