Most deep-sea specialists are specialists. A species adapted to hydrothermal vents lives at hydrothermal vents. A species found on whale falls lives on whale falls. The chemosynthetic habitats of the deep ocean — vents, seeps, falls — share the common feature of being powered by chemistry rather than sunlight, but they differ in temperature, chemistry, substrate, and longevity. Whale falls last decades. Vents last centuries. Seeps last millennia. Adapting to one doesn't automatically equip you for another.
Photinopolynoe iskrae — Iskra's glitter worm — ignores this rule. The iridescent, scale-covered polynoid was found thriving on whale falls, wood falls, and methane seeps off the California coast. Three chemosynthetic habitat types, each with different chemistry and different community structure, all hosting the same species.
The ecological question is how. Each habitat has a distinct chemical regime: whale falls produce sulfide from bone lipid decomposition, methane seeps release methane and hydrogen sulfide from geological reservoirs, wood falls generate sulfide from cellulose decay. The energy sources differ. The toxic compounds differ. The competitive landscape differs. Being a generalist across these environments requires metabolic flexibility that most deep-sea invertebrates lack.
The biogeographic question is how it gets there. These habitats are separated by kilometers to hundreds of kilometers of barren abyssal plain. The worm must disperse through the water column as larvae, landing on isolated patches of chemosynthetic productivity scattered across the seafloor. A habitat generalist that is also a long-distance disperser — rare enough on land, extraordinary at four thousand meters depth.
Named by a high school student after her childhood dog. Iskra means “spark” in several Slavic languages. A spark of iridescence on dead whales, rotting wood, and leaking methane.