Feeding and reproductive behaviour and their effect on catchability of the spanner crabRanina ranina

✍ Scribed by D. G. Skinner; B. J. Hill

• Publisher: Springer-Verlag
• Year: 1987
• Tongue: English
• Weight: 713 KB
• Volume: 94
• Category: Article
• ISSN: 0025-3162
• DOI: 10.1007/bf00392933

✦ Synopsis

The behaviour of 16 adult (8 male and 8 female) spanner crabs (Ranina ranina), collected off southern Queensland, Australia, was monitored continuously in captivity by closed-circuit television for fifteen months from September 1982. Spanner crabs spent most of the time buried in the substrate, emerging mainly only when food became available. They remained emerged for twice as long on feeding days as on days without food. Females responded significantly faster than males to the presence of food. Response was slowest in October and November. There was no correlation between temperature and response time. The average feeding time was 2.0rain (SE=0.12), with no significant difference between males and females. Crabs without food were aggressive towards crabs with food, which sometimes led to fighting and wounding. These interactions also could result in food being transferred from one individual to another. When males interacted, food was transferred more often than when either females, or males and females interacted, Around moulting, male crabs did not feed for 52 d (SE = 9.0) and females for 22 d (SE = 2.2). This habit would reduce the frequency with which newly moulted crabs are caught in the baited tangle nets used by commercial fishermen. In mating interactions, copulation was always initiated by the males. Males dug up other crabs but, apparently unable to distinguish the sex of these individuals, attempted copulation with either sex. The majority of copulations occurred between midday and midnight and in the period August to December. The frequency of copulations with a female increased 10 d before she extruded eggs, after which it dropped to zero for the following 41 to 50 d. Eggs were carried for 39 to 44 din the period September to November. The females remained emerged for long periods before extruding their eggs, but the period shortened