Velvet Worm
A 500-million-year-old predator that hunts by firing slime from its face
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Superpower
Velvet worms hunt by shooting jets of quick-hardening slime from two nozzles (oral papillae) flanking their mouth, with each shot reaching 30cm and covering the prey in strands that set within about one second. They then bite through the snare, inject digestive enzymes into the prey, and drink the liquefied contents. The slime can be re-absorbed and recycled — it costs the animal significant protein to produce, so accuracy matters.
Overview
Velvet worms (Onychophora) are one of the oldest animal lineages on Earth, appearing in the Cambrian fossil record over 500 million years ago essentially unchanged. They're sometimes called the missing link between worms and arthropods: soft, leggy, and vaguely caterpillar-like, they have the unsegmented body of a worm but walk on pairs of stubby, unjointed legs. Their legs work on hydraulic pressure — body fluid is pumped in to extend them, drained to retract them — not on muscles and joints. Most species give birth to live young, and some form cooperative hunting groups with a dominance hierarchy around shared meals.
Found in
Humid, tropical, and subtropical forests worldwide — South America, sub-Saharan Africa, Southeast Asia, Australia, and New Zealand. They dry out quickly and must stay in moist environments under bark, rocks, or leaf litter.
Things worth knowing
- 1
Velvet worm legs have no joints — they're hydraulic, inflated and deflated by internal fluid pressure. Each leg ends in a pair of claws for gripping.
- 2
Their skin breathes — they have tiny spiracles (breathing holes) that can't fully close, meaning they constantly lose water through their skin. They are extremely vulnerable to drying out and die within minutes in direct sunlight.
- 3
Some South African species live in social groups with a strict dominance hierarchy. The dominant female eats first from a shared kill, then the dominant male, then subordinates. Subordinates that try to eat out of turn are aggressively driven back.
- 4
Velvet worm slime is the subject of materials science research — it's a protein-based fiber that sets on contact with air, and scientists are studying it as a potential model for self-assembling biodegradable materials.
- 5
Their fossil record is exceptional: Hallucigenia, one of the most famous Cambrian fossil animals, is now understood to be an early relative of velvet worms — a species so bizarre it was initially reconstructed upside-down.