English: Acanthemblemaria balanorum in shelter at Las Animas in the central Gulf of California, Mexico. Photo taken in July 2009 at 5 m depth Title: Bulletin - Southern California Academy of Sciences Identifier: bulletinsout11022011sout (find matches) Year: 1902 (1900s) Authors: Southern California Academy of Sciences Subjects: Science Publisher: Los Angeles : Southern California Academy of Sciences Contributing Library: Smithsonian Libraries Digitizing Sponsor: Biodiversity Heritage Library View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: MICROHABITAT SPECIALIZATION AND DEPTH RANGE EXTENSION IN TUBE BLENNY 53 Text Appearing After Image: Fig. 1. Acanthemblemaria balanorum in shelter at Las Animas in the central Gulf of California, Mexico. Photo taken in July 2009 at 5 m depth during nearest neighbor surveys. Photo by J. Lund. ascertain densities. Numbers of A. balanorum ranged (mean +/- SD) from 8-28 (20.4 +/- 8.6) individuals per 0.25 m^. These high densities may reflect the very high barnacle densities at this site, though it is difficult to quantify available shelters, as it is not immediately obvious what a chaenopsid considers to be a sufficient shelter. To date, no experiments have been designed to determine what a second limiting factor is for these or similar shelter-dwelling microhabitat specialists, but it is quite possibly an issue of territory size. Males of Acanthemblemaria and several other chaeonpsid genera actively court females, which, upon choosing a suitable male, enter the male's shelter and deposit eggs (Hastings 1986; Hastings 1988; Hastings and Peterson 2011). The males guard the eggs and may simultaneously protect clutches from multiple females (Hastings 1986; Hastings 1988; Hastings and Peterson 2011). Under these conditions, males compete for female choice and for the most desirable shelters (Hastings 1988; Hastings 1992). The high densities of ^. balanorum observed at Las Animas could lead to agonistic interactions that secondarily limit the population size (or density) of this species. In order to begin quantifying the distance between occupied barnacle shelters at the densely populated Las Animas site, I randomly chose an individual A. balanorum and measured the distance to its nearest neighbor. I then measured the distance to that individual's nearest neighbor and repeated the process until I reached ten total individuals. On average (SD), these ten individuals were only 4.4 cm (1.6) from their nearest neighbor. Upon collecting the specimens, I obtained sex and standard length (SL) for each individual and determined that they were, on average (SD), 28.9 mm SL (3.8) and were all sexually mature adults. In fact, to the best of my knowledge, juvenile habitat preference in this species is unknown. The male to female sex ratio was 7:3, indicating the ability of several adult males to live in close proximity to one another and to mature females, which were somewhat evenly dispersed among the males, within this set of ten individuals (numbers one, three, and eight out often; 5, 2.5, and 5 cm from their nearest neighbors, respectively). The presence of some shelters inhabited by less competitive Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.