Darwin’s Bark Spider

Why in News?

Darwin’s bark spider has drawn scientific attention as studies explain why only adult females produce the toughest spider silk ever recorded.

• Darwin’s Bark Spider is a large orb-weaving spider.
• Scientific name – Caerostris darwini.
• Family – Araneidae (orb-weaver spiders).
• Related species – Caerostris kuntneri.
• Habitat – Forests and wetlands in Madagascar.
• They build orb webs directly above rivers or lakes, a habitat other spiders can’t access.
• Distribution – Endemic to Madagascar.
• Characteristics – Females are largely black in colour, with white hairs, and Males are redder and lighter brown in colour.
• Adult females are significantly larger than males.
• Behaviour – Largest orb webs ever recorded, reaching up to 25 metres in width.
• Only large adult females produce exceptionally tough silk, that outperforms steel and most human-made fibres in both strength and toughness.
• Used as safety lines, anchor threads, and escape ropes by the spider.
• Threats – Habitat disturbance from river/wetland degradation and infrastructure projects (e.g., hydroelectric dams).
• Water pollution reduces prey availability and impacts silk quality.
• Ecological Significance – Large river-spanning webs help control insect populations, especially flying insects.

References

1. The Hindu | Darwin’s Bark Spider
2. iNaturalist | Darwin's Bark Spider (Caerostris darwini)