Arthropod Lecture_Rachael

Tailpiece or Telson

  • Tailpiece or Telson is part of the anatomy of arthropods.

Overview of Phylum Arthropoda

  • Includes various body parts such as:

    • Carapace: Protective upper shield.

    • Abdomen: Segmented rear part.

    • Cephalothorax: Fused head and thorax region.

    • Antennae: Sensory appendages.

    • Walking legs: For locomotion.

    • First leg (cheliped): Claw used for defense and grasping.

General Characteristics of Arthropods

  • Segmented animals with jointed legs and exoskeleton made of chitin and protein.

  • The exoskeleton is typically hardened and serves protective functions.

Classification of Arthropods

  • Subphylum Myriapoda: Includes millipedes and centipedes.

  • Subphylum Chelicerata: Includes arachnids like spiders and scorpions.

  • Subphylum Crustacea: Includes crabs, lobsters, and shrimp.

  • Subphylum Hexapoda: Primarily insects.

Why Are Insects Successful?

  • Insects dominate ecological niches and are adaptable to various environments, excluding the ocean.

Uses of Arthropods

  • Important roles in ecosystems as prey, predators, pollinators, and contributors to nutrient cycling.

Arthropod Diversity and Climate Change

  • Understanding arthropod diversity is crucial for assessing the impact of climate change on ecosystems.

Features of Phylum Arthropoda

  • Diverse body plan resulting in capabilities to occupy varied habitats.

  • Abundance: Over 200 million individual arthropods per person on earth.

  • Highly adaptable with both smooth and striated muscles.

Arthropod Body Plan & Characteristics

  • General Body Plan:

    • Hard exoskeleton.

    • Segmented body.

    • Paired jointed appendages.

    • Well-developed cephalization.

  • Muscular System: Complex with striated and smooth muscle fibers.

Metameric Segmentation

  • Body plans include:

    • Cephalothorax and abdomen.

    • Head and trunk.

    • Head-thorax-abdomen.

Exoskeleton: Structure and Function

  • Composed of layered chitin that protects against environmental threats and desiccation.

  • Provides waterproofing to assist in terrestrial life.

  • Highly colored for camouflage and recognition.

  • Drawbacks include limited growth potential as it restricts size increase.

Ecdysis (Moulting)

  • Process necessary for growth requiring periodic shedding of the exoskeleton.

  • Controlled by nervous system and hormones (ecdysone).

  • The new exoskeleton remains soft initially, making it vulnerable during this period.

Stages of Moulting

  • Stages Include:

    • Apolysis: Epidermis separates from old cuticle.

    • Secretion of new procuticle and shedding of old cuticle.

Appendages and Tagmata

  • Appendages grouped as tagmata for specialized functions (walking, reproducing, sensing).

  • Displays great variation in form and function across species.

Sensory and Feeding Mechanisms

  • Well-developed sensory organs (antennae, compound eyes).

  • Specialized appendages for feeding, including grinding and storing mechanisms.

  • Efficacious digestive systems with accessary glands for nutrient absorption.

Circulatory System

  • Closed circulatory system with blood (haemolymph) bathing internal organs.

  • Lack of hemoglobin; oxygen transport via copper-based blood.

  • Simple open system consisting of haemocoel and dorsal contractile heart.

Respiratory System

  • Majority of terrestrial arthropods use tracheae for respiration.

  • Spiracles control air flow and prevent water loss.

Nervous and Excretory Systems

  • Nervous system includes a brain, ventral nerve cord, and multiple sensory structures.

  • Excretory mechanisms involving Malpighian tubules for nitrogen waste and water conservation.

Arthropod Classification Summary

  • Around 1,100,000 known species; a significant number yet to be classified.

  • Categories include Myriapoda, Chelicerata, Crustacea, and Hexapoda based on body structure and adaptations.

Importance of Arthropods in Ecology

  • Function as indicators of ecological health; crucial in food webs and ecosystem services.

  • Examples of therapeutic uses in medicine including the use of maggot therapy and bee venom in treatments.

Conclusion

  • Arthropods showcase a spectacular diversity that plays a vital role in both ecology and human economies.

  • Their adaptation strategies highlight their significant evolutionary success across diverse environments.