Spider (Araneae): Master Weavers of Nature's Webs

Spider (Araneae): Master Weavers of Nature's Webs
This presentation explores the diverse world of spiders, focusing on their anatomy, behavior, web-building techniques, ecological importance, and their role in maintaining environmental balance as skilled predators and fascinating members of the animal kingdom.

1. Spider (Araneae) Presentation by: Roll no: 1 1 st year BPH 6 th batch   Aabhas Pant

2. Contents Introduction of Spider Background Key facts Biological Classification Habit and Habitat Morphology

3. Contd … Life cycle Public health importance Conclusion Recommendation References

4. Introduction With more than 48,000 species described (World Spider Catalog, 2020) A few species have even conquered the aquatic environment  Spider’s silk, venom and hemolymph are a source of inspiration for biological engineering

5. Background Spiders are found on every continent except Antarctica, showcasing their remarkable adaptability to diverse environments. Traditional beliefs and cultural practices in Nepal may influence perceptions of spiders, with some species regarded as symbols of luck or symbol for loan . There are around 386 species of spiders in Nepal .

6. Key facts

7. Contd..

8. Contd..

9. Contd..

10. Contd..

11. Contd..

12. Contd..

13. Contd..

14. Contd..

15. Biological classification Kingdom: Animalia Phylum: Arthropoda Class: Arachnida Order: Araneae (ability to produce silk) Family: Araneidae (orb-weaver spiders), Salticidae (jumping spiders), and Theridiidae (cobweb spiders). Genus and Species : Latrodectus mactans for the Southern black widow

16. Habit and Habitats Terrestrial Arboreal Aquatic Subterranean

17. Morphology

18. Life Cycle

19. Egg Stage: Female spiders typically lay their eggs in silk egg sacs, which provide protection and support for the developing embryos. The number of eggs in a sac can vary greatly depending on the species, with some sacs containing just a few eggs and others containing hundreds. The female spider may deposit the egg sac in a sheltered location, such as under leaves, inside crevices, or in burrows, to keep them safe from predators.

20. Contd.. The eggs inside the sac are surrounded by a protective coating of silk, which helps regulate moisture levels and provides structural support. Spider eggs are usually small and spherical, often ranging in size from a fraction of a millimeter to a few millimeters in diameter, depending on the species.

21. Egg sac The silk egg sac serves as a protective casing for the developing spider embryos. The structure and appearance of egg sacs can vary among spider species, with some sacs being smooth and spherical, while others may have irregular shapes or textures.

22. Contd.. The silk used to construct the egg sac is produced by specialized glands located in the abdomen of the female spider. The silk is secreted as a liquid and hardens upon contact with the air, forming a strong and flexible material. Egg sacs may be attached to substrates such as plant leaves, bark, rocks, or soil, or they may be carried by the female spider until the eggs hatch.

23. Spiderlings Spiderlings are the immature offspring of spiders that hatch from the eggs inside the egg sac. Spiderlings are typically small and vulnerable, often lacking the distinctive features of adult spiders.

24. Contd.. They may resemble miniature versions of adult spiders but may have different coloration or markings. Spiderlings disperse from the egg sac and begin their journey into the world, searching for food and suitable habitats. Spiderlings undergo several molts as they grow, shedding their exoskeletons to accommodate their increasing size. Each molt is followed by a period of growth before the next molt occurs.

25. Contd.. Spiderlings may exhibit behaviors such as ballooning (using silk threads disperse to new areas) or social aggregations (grouping together for protection or hunting).

26. Adult Adult spiders are fully developed and capable of reproducing. The timing of maturity varies among species and can depend on factors such as temperature, food availability, and environmental conditions. Adult spiders play important roles in ecosystems as predators of insects and other arthropods, contributing to pest control and maintaining ecological balance.

27. Public health importance While spiders themselves may not directly impact public health in the same way as disease vectors or environmental pollutants, their presence and ecological contributions indirectly support human health and well-being. Some point that shows the public health importance are : Pest Control Ecosystem Services Biological Research Ecotourism and Education Indicators of Environmental Health

28. Preventive measures Seal Entry Points Keep a Clean Environment Remove Spider Webs Reduce Outdoor Lighting Use Essential Oils Keep Food Sealed Regular Inspections Chemical agent : Insecticide like pyrethroids

29. Conclusion In conclusion, spiders play a vital role in ecosystems worldwide, contributing to pest control, nutrient cycling, and biodiversity maintenance. Despite their often-misunderstood reputation, spiders are fascinating creatures with diverse habits and adaptations that allow them to thrive in a wide range of habitats.

30. Recommendation Increase public awareness and understanding of spiders ecological importance, diversity, and beneficial roles in ecosystems. Protect and preserve natural habitats that support diverse spider populations, including forests, wetlands, grasslands, and urban green spaces. Promote the use of integrated pest management practices in agriculture, forestry, and urban settings to minimize reliance on chemical pesticides and encourage natural pest control by spiders and other beneficial predators.

31. References https://www.sciencedirect.com/science/article/abs/pii/S0006320721000720 Lewis R. Unraveling the weave of spider silk. Bioscience .  1996; https://en.wikipedia.org/wiki/Spider https://www.who.int/news-room/fact-sheets/detail/animal-bites Medical and Veterinary Entomology by Gary R. Mullen and Lance A. Durden

32. Thank You