Zombie Worm (Osedax)
A worm with no mouth and no stomach that eats whale bones using acid secreted through its skin — while carrying up to 100 microscopic males inside its body
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Superpower
Osedax (meaning 'bone eater') has no mouth, no gut, and no digestive system. Instead, it grows root-like structures into whale bone that secrete acid to dissolve the bone matrix, releasing fats and proteins that symbiotic bacteria living in the roots then break down for the worm. The female grows up to 5cm. The males are microscopic — between 50 and 100 of them live permanently inside the female's body as internal parasites, never developing beyond a larval state, existing solely to provide sperm.
Overview
Osedax were only discovered in 2002 when a research submarine came across a whale fall (a whale carcass on the seafloor) and found it covered in what appeared to be flowers — actually the feathery plumes of millions of these worms. Since then, over 20 species have been described. They're found on whale, fish, and even cow bones on the deep seafloor, and appear to be one of the primary agents that recycle vertebrate bone in the deep ocean. Before their discovery, it was believed that bone was simply dissolved slowly by seawater chemistry.
Found in
Whale falls and other large vertebrate carcasses on the deep seafloor worldwide, particularly in the Pacific and Atlantic Oceans at depths of 30–4,000m.
Things worth knowing
- 1
The discovery that males live inside females as permanent internal parasites was so surprising that researchers initially thought the masses inside females were larvae — they're adults who never develop further.
- 2
Different Osedax species have different root structures specialized for different bone types and densities — suggesting rapid evolutionary radiation after the discovery of the whale-fall ecological niche.
- 3
Whale falls are the richest single food sources in the deep ocean — a single large whale carcass provides more organic material than 2,000 years of normal seafloor 'marine snow' rain in the same area.
- 4
Osedax's acid-secreting roots have been found on bird bones, fish bones, and even cow bones deposited at sea — suggesting the group is more ecologically versatile than initially thought.
- 5
Female Osedax live in a gelatinous tube anchored to bone. The visible part — the feathery plume — is a respiratory gill. The buried part dissolves the bone. The whole animal is, in a sense, a living acid drill.