Invertebrates
Vent Shrimp
Rimicaris exoculata · also called blind vent shrimp
Lacking any functional eyes yet somehow finding its way to scalding hydrothermal vents, a vent shrimp relies on a specialised light-sensing organ on its back, farming bacteria on its own body in swarms thousands strong.
Overview
The vent shrimp, Rimicaris exoculata, is an eyeless crustacean native to hydrothermal vent habitat recorded along the Mid-Atlantic Ridge. Its unique back-mounted light-sensing organ, habit of farming bacteria directly on its own body, and tolerance for extreme vent conditions make it one of the most specialised chemosynthesis-dependent animals found anywhere in the ocean.
Sight traded for a different kind of sense
Having abandoned conventional vision entirely, the vent shrimp instead relies on a highly specialised organ tuned to detect the faintest thermal glow of a distant vent, a sensory trade-off perfectly suited to a life spent entirely in the dark.
Status
Least Concern, though detailed population trends remain largely unknown across the full range of known hydrothermal vent sites.
Vent Shrimp: common questions
How does the vent shrimp find hydrothermal vents without eyes?
This species has a specialised light-sensing organ positioned on its back rather than in typical eye sockets, believed to detect the extremely faint thermal glow given off by hydrothermal vents, allowing it to locate vents despite lacking functional image-forming eyes.
How does the vent shrimp get its food?
This species cultivates colonies of chemosynthetic bacteria directly on its own body, particularly around its mouthparts, later scraping off and consuming the bacteria as its primary food source.
Why doesn't the vent shrimp need normal eyes?
This species lacks functional image-forming eyes entirely, an adaptation to a habitat where traditional vision offers little advantage in the near-total darkness surrounding hydrothermal vents on the deep seafloor.
How many vent shrimp can gather around a single vent?
This species can form enormous, densely packed swarms numbering in the thousands around active hydrothermal vent chimneys, taking advantage of the concentrated chemical-rich water needed by its bacterial food source.