While exploring the water column during the 700-meter (2,297-foot) transect of Dive 20 of the 2021 North Atlantic Stepping Stones expedition, we imaged this physonect siphonophore. Although siphonophores may appear to be single organisms, they are actually colonies of many individual hydrozoans (called zooids), each specialized for different functions such as swimming, feeding, reproduction, and defense.
Physonect Siphonophore
Image courtesy of NOAA Ocean Exploration, 2021 North Atlantic Stepping Stones: New England and Corner Rise Seamounts. Download larger version (jpg, 886 KB).

While exploring the water column during the 700-meter (2,297-foot) transect of Dive 20 of the 2021 North Atlantic Stepping Stones expedition, we imaged this physonect siphonophore. Although siphonophores may appear to be single organisms, they are actually colonies of many individual hydrozoans (called zooids), each specialized for different functions such as swimming, feeding, reproduction, and defense.

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