Biology – 1.3 Features of organisms | e-Consult
1.3 Features of organisms (1 questions)
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The main features used to classify organisms as arthropods are:
- Segmented body: The body is divided into distinct segments, often grouped into tagmata (head, thorax, abdomen).
- Exoskeleton made of chitin: A hard, protective outer covering that provides support and protection.
- Jointed appendages: Legs, antennae, mouthparts, etc., are jointed, allowing for a wide range of movement.
- Anterior nerve cord and a ventral nerve cord: A simple nervous system.
- Open circulatory system: Blood (hemolymph) circulates freely in the body cavity.
- Compound eyes or simple eyes (ocelli): Provide visual information.
Three examples of adaptations these features provide for life on land are:
- Exoskeleton: Provides protection from desiccation (drying out), mechanical damage, and predators in the terrestrial environment.
- Jointed Appendages: Allow for efficient locomotion on land, enabling movement over varied terrain. Different types of appendages are adapted for different functions (e.g., walking, climbing, feeding).
- Open Circulatory System: While less efficient than a closed system, it is sufficient for the arthropod's metabolic needs in a terrestrial environment. The open system allows for rapid transport of hemolymph to muscles.