Decapod Crustacea of the Californian and Oregonian Zoogeographic Provinces 3371 Author Wicksten, Mary K. text Zootaxa 2012 2012-07-04 3371 1 307 journal article 1175­5334 Family Sergestidae Dana, 1852 Sergestids are widespread pelagic shrimp. The second abdominal somite does not overlap the first. Males have a petasma, females have a sperm receptacle between the third or third and fourth pereopods. In the male, the inner antennular flagellum is modified as a prehensile clasping organ used in copulation. The rostrum is short. Neither the third maxilliped nor the pereopods bear exopods. Pereopods 4, 5 are shorter than the anterior pereopods. Two color patterns are common among the species: partly pigmented, with red pigment in the anterior body and translucent appendages and abdomen with small pigment spots; and solid bright red. The partly pigmented species occur at lesser depths than the bright red ones, which often live at depths of 500 m or more. Many species carry on daily vertical migrations, occurring at lesser depths during the night than by day. Sergestids have extremely long antennal flagella in life. In Eusergestes similis , the antennae are extended during swimming. These flagella bear a kink at about half the length of the flagella. The antennae are well supplied with small sensory endings, which may detect prey by vibration or chemosensation, or may provide warning of approaching predators ( Cowles 1994 ). Sergestids are primarily predators, especially of copepods. They also eat ostracods, euphausiids, pteropods, chaetognaths and cnidarians ( Flock & Hopkins 1992 ). Much of the classification of sergestids is based on the shape of the copulatory structures. The key given here follows those of Wasmer (1972) and Kensley (1972) , but also applies the nomenclature of the genera given by Judkins & Kensley (2008) .