Friday, April 15, 2011
Hysterocarpus traski is listed in the 2nd edition of Fishes of the World (Nelson, 1984) as the exceptional species in the family Embiotocidae, for having 15-19 dorsal spines, rather than the 6-11 of the other species in this family, also known as the surfperches.
Like the guppies I used to study, these fish are viviparous, they give birth to live young, and the male's anal fin is modified as an intromitent organ (i.e. a wang). At least according to this book, with this section apparently based on Tarp (1952), the family is restricted to the coastal North Pacific (rarely in fresh water). I know I've met members of this family, though probably not this species (judging from the picture), when scuba diving around Vancouver Island and Howe Sound near the city of Vancouver.
Tarp, F.H. 1952. A revision of the family Embiotocidae (the surfperches). Fish Bull. Calif Dep. Fish Game 88: 99 pp.
Photo from here.