Grove M W, Woodin S A
Biol Bull. 1996 Jun;190(3):359-366. doi: 10.2307/1543028.
The pea crab Pinnixa chaetopterana (Brachyura: Pinnotheridae) lives in the tubes of the host polychaetes Chaetopterus variopedatus and Amphitrite ornata. While attraction to host odor cues is common in symbiotes, P. chaetopterana resident in Chaetopterus tubes apparently show no attraction to water-borne cues from either host. Because crabs resident in Amphitrite tubes are significantly reduced in their maximum body size and thus clutch size, switching between hosts should occur. We therefore tested the hypothesis that the crabs use odor cues from conspecifics or from the competing crab Polyonyx gibbesi (Anomura: Porcellanidae) when locating a new host. Crabs collected from Amphitrite are significantly attracted to Chaetopterus hosts which contain a mixed sex pair of conspecifics. Females show a strong tendency to avoid hosts containing Polyonyx, but males do not. Neither sex is attracted to unoccupied Chaetopterus or Amphitrite hosts, but both are significantly attracted to isolated conspecifics. This attraction could serve as a reliable means of locating suitable new hosts when switching hosts in the field. Attraction to conspecific odors would also increase the chances of finding a suitable mate already present in a new host.
豌豆蟹Pinnixa chaetopterana（短尾派：豆蟹科）生活在宿主多毛类动物Chaetopterus variopedatus和Amphitrite ornata的管子里。虽然共生生物对宿主气味线索产生吸引是常见现象，但居住在Chaetopterus管子里的P. chaetopterana显然对来自任何一种宿主的水溶性线索都没有吸引力。由于居住在Amphitrite管子里的螃蟹最大体型以及因此产的卵块大小显著减小，所以应该会在宿主之间发生转换。因此，我们检验了这样一个假设：螃蟹在寻找新宿主时会利用来自同种个体或竞争蟹Polyonyx gibbesi（异尾派：瓷蟹科）的气味线索。从Amphitrite采集的螃蟹会被含有一对雌雄同种个体的Chaetopterus宿主显著吸引。雌性表现出强烈的倾向避开含有Polyonyx的宿主，但雄性则不会。两种性别对未被占据的Chaetopterus或Amphitrite宿主都没有吸引力，但两者都被单独的同种个体显著吸引。这种吸引在野外转换宿主时可以作为找到合适新宿主的可靠方式。对同种气味的吸引也会增加在新宿主中已经存在合适配偶的几率。
