18.2 Adaptive Features

2026 Syllabus Objectives

  1. Describe an adaptive feature as an inherited feature that helps an organism to survive and reproduce in its environment
  2. Interpret images or other information about a species to describe its adaptive features
  3. Explain the adaptive features of hydrophytes and xerophytes to their environments

What Are Adaptive Features? 🔑

Every organism has features that help it to survive in its environment. These features can affect an organism's chances of reproduction, and therefore the chances of its genes being passed on to the next generation.

Adaptive feature: an inherited feature that helps an organism to survive and reproduce in its environment.

Key Point: Adaptive features are inherited (passed from parents to offspring through genes) and increase an organism's survival and reproductive success.


Examples of Adaptive Features in Animals 🐟

Fish Adaptations

All fish share certain adaptive features:

  • Gills allow them to obtain oxygen under water
  • Different fish species have evolved additional specific adaptations based on their habitat and lifestyle

Comparing Two Fish Species

SpeciesEnvironmentAdaptive Features
Pygmy SeahorseCoral reefs, among sea fans• Perfect camouflage - pink and white coloration matches sea fans
• Small size for hiding
TunaOpen ocean• Streamlined body for fast swimming
• Strong swimming muscles
• Teeth for killing prey
• More mitochondria in muscle cells for greater energy release through aerobic respiration

Cellular and Biochemical Adaptations

The differences between species extend beyond visible features:

  • Mitochondria numbers: Tuna may have more mitochondria in their muscle cells than seahorses to provide more energy through aerobic respiration for faster swimming
  • Digestive enzymes: Different species have different enzymes in their digestive systems suited to their different diets

Xerophytes: Plants Adapted to Dry Environments 🌵

What Are Xerophytes?

Xerophyte: a plant that has adaptive features that help it to survive in an environment where water is scarce.

Plants that live in deserts can easily run short of water, especially if the temperatures are hot. Desert plants, such as succulents and cacti, must be well adapted to survive in these difficult conditions.

Important: All xerophytes have adaptations that help them to conserve water and survive in a difficult dry environment.

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