Spider Bio 3150 FINAL

Spider Study Guide

1. Important Spider Families with Extensive Knowledge

   • Salticidae (Jumping Spiders):

     • Notable traits: Excellent vision (large anterior median eyes), intricate courtship displays, and complex predatory strategies.

     • AME (Anterior Median Eyes):

       • Large, image-forming eyes that provide acute resolution for hunting.

       • Specialized for detecting and focusing on prey with high precision.

     • Other Eyes:

       • Primarily motion sensors, helping detect movement in the environment.

     • PLE (Posterior Lateral Eyes):

       • Function as motion detectors; their cones can move to focus and form clearer images.

       • Enable almost 360-degree vision, aiding in navigation and predator detection.

     • Portia (a genus of Salticidae):

       • Notable for object permanence and advanced cognitive hunting strategies.

       • Uses a combination of visual input and tactile web cues to plan complex predatory attacks.

   • Theridiidae (Cobweb Spiders):

     • Notable traits: Use of sticky silk for prey capture, venom potency in some species (e.g., Latrodectus), and maternal care behaviors.

2. Venomous Spider and Scorpion Groups

   • Spiders:

     • Latrodectus (widow spiders): Neurotoxic venom; found worldwide in temperate and tropical habitats.

     • Loxosceles (recluse spiders): Cytotoxic venom; located in North and South America, inhabiting dry, dark environments.

     • Atrax (Australian funnel-web spiders): Neurotoxic venom; found in Australia’s forests and urban areas.

   • Scorpions:

     • Family: Buthidae (e.g., Androctonus, Leiurus).

     • Habitat: Deserts and arid regions worldwide; venom typically neurotoxic.

3. Human-Venom Interaction

   • Few spiders are venomous to humans due to their fang size or venom composition being specialized for prey.

   • Spider bites may indicate infections or allergic reactions.

   • Contrast:

     • Latrodectus: Neurotoxic venom causing systemic symptoms.

     • Loxosceles: Cytotoxic venom causing necrosis.

   • Bite identification: Spider observation, symptoms, and bite site.

   • Most bites (50%) do not result in envenomation.

4. Threats to Spider Populations

   • Habitat destruction, climate change, pesticide use, and fear of spiders (arachnophobia).

   • Mygalomorphs are at greater risk due to limited dispersal abilities and habitat specialization.

   • Benefits of venoms: Medical applications (e.g., painkillers, neuroprotective agents). For example, Lyoma targets myon cells for therapeutic purposes. Additionally, Phoneutria venom has been researched for its potential role in treating priapism and erectile dysfunction (ED).

5. Most Dangerous Scorpion Family

   • Family: Buthidae.

   • Recognition: Slender pedipalps, large metasoma with venomous sting.

6. Group-Living in Spiders

   • Benefits:

     • Cooperative prey capture (e.g., Anelosimus eximius).

     • Enhanced defense against predators.

   • Costs:

     • Increased competition for resources.

     • Risk of disease transmission.

   • Differences:

     • Cooperative species share resources and care for offspring (e.g., Stegodyphus).

     • Colonial species live together but hunt individually.

7. Sociality in Spiders

   • Examples:

     • Transient parental care: Metepeira incrassata

     • Prolonged subsocial: Delena cancerides

     • Cooperative: Stegodyphus, Anelosimus eximius

   • Key traits: Level of cooperation, resource sharing, and offspring care.

8. Anelosimus Sociality and Habitat

   • Sociality correlates with:

     • Large prey size: Favoring cooperation.

     • Elevation: Increased sociality at lower elevations.

     • Rain: High rain favors web-sharing.

9. Origins of Sociality

   • Independent origins:

     • Cooperative: Anelosimus eximius – prey sharing and communal care.

     • Subsocial: Stegodyphus – prolonged maternal care.

     • Colony initiation: Ballooning in some species; budding in others.

10. Parental Care in Non-Spider Arachnids

    • Scorpions: Maternal care; offspring carried on the mother’s back, live birth with young dispersing shortly after.

    • Amblypygids: Guarding eggs and juveniles.

    • Pseudoscorpions: Brood sacs, guarding young, and hitching rides on other arthropods for dispersal (phoresy).

    • Opilionids: Paternal care observed in some species, carrying and protecting eggs.

11. Antipredator Defenses

    • Examples:

      • Crypsis: Salticidae (camouflage).

      • Urticating hairs: Theraphosidae.

      • Autotomy: Lycosidae (leg shedding).

    • Predators: Birds, other arachnids, insects like Portia.

12. Bird Predation

    • Birds: Visual predators.

    • Influence: Selection for crypsis, speed, and burrowing.

    • Key predators: Small insectivorous birds (e.g., warblers).

13. Wasp Predation

    • Pompilid wasps: Target large spiders.

    • Sphecid wasps: Prey-specific hunters.

    • Crabronid wasps: Broader diet.

    • Escape likelihood: Higher against crabronids due to less specialized hunting.

14. Non-Wasp Predators

    • Examples:

      • Portia: Mimicry and cognitive hunting.

      • Ants: Group predation.

      • Mantids: Ambush predators.

15. Spiders and Pest Control

    • Limitation: Generalist diet; intraguild predation (IGP) and slow metabolism can reduce overall pest control efficiency.

    • Suggested trait: Increased prey specificity.

16. Non-Spider Arachnid Traits

    • Opilionids: Aggregations for defense.

    • Scorpions: Fluorescence under UV light.

    • Amblypygids: Long antenniform legs.

    • Pseudoscorpions: Phoretic dispersal.

    • Thelyphonids: Acetic acid spray.

17. Salticid Vision

    • AME: Acute resolution for hunting.

    • PLE: Motion detection and navigation.

    • Portia: Combines visual planning with web-based cues.

Key Terms:

• Selfish herd: Safety in numbers.

• Necrotic arachnidism: Tissue damage from venom.

• Neurotoxic: Affects nervous system.

• Urticating hairs: Defensive bristles.

• Matriphagy: Offspring consuming the mother.

• Chelate chelicerae: Pincer-like jaws.