David and Goliath: potent venom of an ant-eating spider (Araneae) enables capture of a giant prey

Abstract

It is rare to find a true predator that repeatedly and routinely kills prey larger than itself. A solitary specialised ant-eating spider of the genus Zodarion can capture a relatively giant prey. We studied the trophic niche of this spider species and investigated its adaptations (behavioural and venomic) that are used to capture ants. We found that the spider captures mainly polymorphic Messor arenarius ants. Adult female spiders captured large morphs while tiny juveniles captured smaller morphs, yet in both cases ants were giant in comparison with spider size. All specimens used an effective prey capture strategy that protected them from ant retaliation. Juvenile and adult spiders were able to paralyse their prey using a single bite. The venom glands of adults were more than 50 times larger than those of juvenile spiders, but the paralysis latency of juveniles was 1.5 times longer. This suggests that this spider species possesses very potent venom already at the juvenile stage. Comparison of the venom composition between juvenile and adult spiders did not reveal significant differences. We discovered here that specialised capture combined with very effective venom enables the capture of giant prey.

Venom gland size and venom complexity—essential trophic adaptations of venomous predators: A case study using spiders

“…Instead, it may indicate that their venom contains components that are very effective in immobilizing prey in small amounts. Existence of such compounds is further supported by the absence of an ontogenetic shift in prey preference (from small to large prey) and the venom complexity in ant‐eating specialists reported so far (Cárdenas, Šedo, & Pekár, ): Even tiny spiderlings were able to subdue ants that were dozens of times larger than themselves with a single short bite (Pekár et al., ).…”

“…Previous studies on venom metering in spiders revealed that generalists can alter the amount of venom injected based on the behaviour of prey; specifically agile, larger and dangerous prey required more venom to be paralysed (Kuhn‐Nentwig, Schaller, & Nentwig, ; Malli, Kuhn‐Nentwig, Imboden, & Nentwig, ). Some spider specialists catch dangerous prey (ants or spiders) (Pekár & Toft, ), and typically hunt prey larger than themselves (e.g., García, Viera, & Pekár, ; Michálek et al., ; Pekár, Šedo, Líznarová, Korenko, & Zdráhal, ). Thus, to effectively paralyse such prey, specialists should inject more venom than generalists.…”

Hunting Without a Web: How Lycosoid Spiders Subdue their Prey

“…However, the composition and quantity of the venom may restrict the size of prey items that a spider is able to subdue (Pekár et al. ).…”

“…; Pekár ; Pekár et al. , ) spiders, as well as in polyphagous salticid spiders (Jackson , , ; Jackson & Hallas ) that exhibit a typical jumping behaviour. However, knowledge about the actual prey capture mechanisms in the majority of polyphagous free hunting spiders is very limited (Melchers ; Rovner , ; Jackson ), and comparative studies are lacking to date.…”

Metabolic specialisation on preferred prey and constraints in the utilisation of alternative prey in an ant-eating spider

“…All these prey types are hard to handle. Spiders exploiting such prey are expected to evolve a variety of specific adaptations which enable them to overcome prey defences, such as highly potent venom (Pekár et al, 2014) or an extremely thick cuticle (Pekár et al, 2011), or to develop specific hunting tactics (Jackson and Hallas, 1986;Dippenaar-Schoeman et al, 1996;Jackson et al, 1998;Pekár, 2004). However, these specific adaptations may constrain the exploitation of an alternative prey (Pekár, 2005;Cárdenas et al, 2012).…”