Pelagic shrimp play dead in deep oxygen minima

Area of Science:

• Marine Biology
• Deep-Sea Ecology
• Crustacean Behavior

Background:

• Pelagic crustaceans are abundant but poorly understood.
• The deep pelagic shrimp Hymenopenaeus doris inhabits low-oxygen zones in the eastern Pacific.

Purpose of the Study:

• To investigate the natural behavior of Hymenopenaeus doris.
• To understand the functional significance of observed behaviors.

Main Methods:

• In situ observation using a remotely operated vehicle (ROV).
• Analysis of shrimp orientation, activity, and metabolic rates.
• Comparative behavioral observations of Petalidium suspiriosum.

Main Results:

• H. doris specimens appeared inactive and inverted, resembling molted exoskeletons.
• Subtle appendage shifts controlled orientation and sink rate.
• Low metabolic rates (0.55-0.81 mg O2 kg-1 min-1) correlate with hypoxia tolerance and inactivity.
• Similar behavior was observed in Petalidium suspiriosum.

Conclusions:

• The observed behavior of H. doris is hypothesized to be a predator avoidance mechanism against visually-cued predators.
• Reduced activity and low metabolic rates are adaptations to deep-sea, low-oxygen environments.
• This behavior may be more widespread among deep-sea decapods.