A single creature of thousands
Deep within the Monterey Canyon, at depths between 700 and 1,000 meters, lives an organism that defies standard classification. A siphonophore, such as the giant Praya dubia, appears to be a single animal, but it is a colony of thousands of genetically identical individuals called zooids. These zooids are so specialized they cannot survive on their own. The entire structure develops from a single fertilized egg, which buds asexually to produce the entire colony.
Siphonophores belong to the phylum Cnidaria, making them relatives of jellyfish and corals. Each colony is built from distinct types of zooids with specific functions. Nectophores are powerful, medusa-like bells that propel the colony through the water. Gastrozooids are the feeding polyps, each equipped with a long tentacle to capture prey. Gonozooids handle reproduction, and bracts act as protective shields. All these parts are physically connected, sharing a common gut, and functioning as a single, coordinated being.
Hunting in the deep
The giant siphonophore is an active predator, employing a "sit-and-wait" strategy. It deploys a vast, nearly invisible curtain of stinging tentacles that can stretch for tens of meters. These tentacles are armed with nematocysts, harpoon-like cells that inject a paralyzing toxin into any small crustacean or fish that drifts into the trap..
Many siphonophore species are bioluminescent. Praya dubia produces a bright blue light, which it may use as a lure to attract prey in the dark waters of the mesopelagic zone. Researchers at the Monterey Bay Aquarium Research Institute (MBARI) have even discovered species in the genus Erenna that produce a rare red fluorescence. This red light may mimic the glow of small crustaceans, tricking fish into approaching the siphonophore's waiting tentacles. Though some can reach lengths greater than a blue whale, their bodies are incredibly fragile and often no thicker than a broomstick.