Oikopleura dioica

Taxon-Order: 
Appendicularia (or Larvacea)

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Distribution: 
Warm-temperate waters in Atlantic, Indian and Pacific Oceans, Mediterranean and Red Seas.
Habitat: 
Neritic.
Size: 
1-8 mm
Predators: 
The ctenophore, Mnemiopsis leidyi, copepods, fish.
Useful Facts or Characters: 

Small, nearly transparent zooplankton with a trunk and tail.

Natural History: 

O. dioica is the only species of appendicularian to have separate sexes; others are hermaphrodites.  They secrete mucus filtering structures called houses, which are used to trap small particles.  O. dioica builds as many as six houses per day; they can be found in high numbers.  They are filter feeders.

References: 

video source: http://www.youtube.com/watch?v=rtVv4Lf1jkE