Phronima sedentaria

Taxon-Order: 

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Distribution: 
Temperate and tropical waters; in the Pacific 36° N-55° S.
Habitat: 
Surface to deep water.
Size: 
12-42 mm
Diet: 
Zooplankton.
Predators: 
Fish.
Useful Facts or Characters: 

Known to be associated with gelatinous zooplankton, such as pelagic tunicates.

Natural History: 

They make homes in hollowed out salps, then lay eggs inside the barrel.  The eggs hatch inside the barrel, which is then food for the young amphipods.