Social behaviour in spiders is rare at best: of the 40 000 described species of spiders, merely 23 are considered social, cooperatively. Delena cancerides is a social species of huntsman spider native to Australia. This species is unique among social spiders, having developed social behaviour without a web. It is thought that this type of social behaviour in Delena cancerides has evolved through the sub-social route, the attachment of an ancestrally occurring extent of maternal care and the slowed dispersal of juveniles. Most social spiders show no aggression towards non-family individuals, suggesting that spiders cannot recognize each other; regardless, Delena cancerides individuals are highly aggressive towards individuals of the same species introduced from outside their colony group. To determine if selective aggression in Delena cancerides has its basis in individual recognition, tolerance to each other behaviour was tested in the context of family and size. I saw that, in general, juveniles preferred to starve even to the point of death than engage in cannibalism of any member of the same species, related or not. However, where cannibalism did occur, non-kin were preferentially eaten, indicating that this species can recognize kin. Size maximums and minimums were established, below which adults tolerate juveniles and above, aggressive interactions leading to fights to the death occur.
Article written by
James Whitcher
March 2022
The cycle of the colony starts with a female that finds a mate. Males wander around throughout the night and search for females using pheromones, and once they see the female, he mates. Like other huntsmen, the female is aggressive towards the male sometimes and, lots of the time, eats the male after mating. Around 3 to 5 months later, the eggs are laid, and they hatch 1 to 2 months later. In my experience, Delena cancerides slings are incredibly large, with almost 10mm leg span with a 5mm body. Most other huntsmen species, even some of the largest species such as Beregama aurea and Typostola barbata, have young smaller than a 5mm leg span. Albeit, there are fewer eggs than all other huntsman species, and the egg sacs are modified to be plastered to a piece of bark instead of a sac with silk strands. Most of the time, there are less than 100 slings but considering their survival rates are close to 100%, most of the slings get reasonably large. Once these eggs hatch, the mother crowds over them for a week or so until they have their second moult. After this, they move about but not far from the mother. They stay with the mother for six months until they turn sub-adult. Once they reach this stage, they leave the mother to start a new colony, and the mother usually lays another egg sac. After only one mating, the mother can hold onto the spermatophore for up to 5 other egg sacs. The mother's time between each egg sac is frequently around five months.
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Fig 2; Social huntsman distribution map
Social huntsmen prefer lower temperatures through the night but mostly, lower humidity. For this reason, they are not found further north than Rockhampton. There may be some errors in the map due to false identifications.
Fig.3) Captive bred egg sac. this mother has already laid 5 egg sacs which grew up into healthy adults. This colony currently is nearing its end with only four sub adult children but when these eggs hatch the cycle will start all over again.
As seen in Fig.3, within the family groups, there are numerous stages of life for the huntsmen, with slings to sub-adults all coexisting together. Even more than just living together, these spiders recognize each other and, most of the time, share food. In almost all feeding instances of a colony, the matriarch grabs the live prey, then kills it and gives it to the young to feed on.
SEQ form Delena cancerides. These spiders are much more locality based and have vast changes over Australia. Most of the current colonies kept at Australian Invertebrates are South Australia locale (Mt Lofty) as their much easier to keep and grow larger with more young. There is also a couple SEQ locale colonies and one Mt Kosciuszko Delena cancerides colony that has been identified as not Delena kosciuskoensis.