Chemical detection of sex and condition in the crayfish Orconectes virilis

Individual crayfish ( Orconectes virilis ) were tested for responses to water containing conspecific individuals of several sex-status categories. Isolated males did not react to “self” water but did show aggressive postures while isolated, nonself male water was introduced. Males' responses to female water was different from responses to male water. Water from aggressing males elicited fewer agonistic postures and more “neutral” postures. Females showed little difference in response to waters from different categories of conspecifics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44870/1/10886_2004_Article_BF00988201.pd

Source and nature of disturbance-chemical system in crayfish

The responses of crayfish to water from aquaria containing either undisturbed or disturbed animals were observed. The crayfish Orconectes propinquus and O. rusticus showed no response to disturbed-conspecific water. Individuals of O. virilis respond not only to disturbed crayfish but to other taxa (the leech Macrobdella decora , the darter Etheostoma exile , and rock bass Ambloplites rupestris ), but not to the painted turtle Chrsymes picta . Additional tests indicated partial responses by O. virilis to ammonium and to a chemical or chemicals released from the green gland of crayfish. Ablation experiments indicated the antennules as the site of reception of the chemicals. Additional behavioral tests indicated that detection of the disturbance chemical(s) results in the crayfish showing low-level alert for more than 15 min, once an initial priming period has passed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44879/1/10886_2005_Article_BF01026936.pd

Alarm responses in the crayfish Orconectes virilis and Orconectes propinquus

Individuals of two species of crayfish ( Orconectes virilis and O. propinquus ) were tested in the laboratory for responses to chemicals released from physically damaged conspecifics. Individuals of O. propinquus did not show an alarm response to crushed conspecifics. Individuals of O. virilis responded to a water-borne substance released from crushed conspecifics by assuming an intermediate posture and ceasing movement. Similar alarm responses were shown by individuals of O. virilis to crushed congeneric individuals ( O. propinquus ), and these responses were not eliminated by either freeze-thawing the crayfish used to prepare the signal or by treating freshly crushed crayfish with the enzyme trypsin. Individuals of O. virilis showed strong feeding responses to solutions prepared from frozen fish flesh but showed a mixture of alarm and feeding responses to freshly killed fish. These results indicate that the alarm substance used by O. virilis is widespread.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44886/1/10886_2005_Article_BF02059878.pd