This video from the Monterey Bay Aquarium Research Institute (MBARI) in California in the USA says about itself:
Zombie shrimp play dead to avoid being eaten
28 November 2018
While exploring the depths of the Gulf of California with the remotely operated vehicle Doc Ricketts, MBARI researchers saw an eerie sight: the small shrimp, Hymenopenaeus doris, hanging upside down, motionless in the water. At first, the shrimp appeared dead, but a closer look revealed that the animal was making tiny adjustments of its antennae and legs to maintain a head-down position while very slowly sinking. When the submersible got too close, the shrimp sprang back to life and quickly swam away.
While performing this “zombie-like“ behavior, the shrimp looked a lot like a discarded exoskeleton sinking slowly through the dark midwater. The researchers speculate that the shrimp might reduce their chances of being eaten by mimicking a sinking molt.
This odd behavior might also be an adaptation to conserve energy, since the shrimp live at depths where the seawater contains very little oxygen. Animals found in low-oxygen environments have a harder time moving rapidly or for long distances.
The researchers observed three zombie shrimp hanging right underneath large mucous webs or nets. Many deep-sea animals use mucous webs to gather marine snow (small particles of debris drifting down from the surface) for food. The biologists were unable to confirm a connection between the shrimp and the webs, leaving this mystery to be solved on a future expedition.
For more information see here.
Publication: Burford BP, Schlining KL, Reisenbichler KR, Robison BH (2018) Pelagic shrimp play dead in deep oxygen minima. PLoS ONE 13(11): e0207249.
Video editor: Kyra Schlining
Music: Stranger Danger (YouTube audio library)