How Corals Feed: Symbiosis, Nutrition and Survival Under Stress

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A coral skeleton records growth, but living tissue supplies the energy that makes growth possible. Corals are animals, yet many reef corals obtain energy through a partnership with photosynthetic microorganisms. They can also feed on external resources. Understanding these energy pathways helps explain why changes in light, food and water conditions can affect coral growth and survival. [1] Two important energy pathways In photosymbiotic corals, algal partners capture light energy and share products of photosynthesis with the host. The animal also obtains food through heterotrophy, including the capture or uptake of organic resources. Their relative contributions differ among species and environments. [1] Symbiosis illustration, Figure 1 from the bleaching overview; used here to explain the nutritional partnership. Image: Norma Olguín-López and colleagues (2017) , IntechOpen source , CC BY 3.0 . Reproduced without scientific alteration. What does trophic plasticity mean? Trophic plasti...
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Gemological Microscope and its uses

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Gemological Microscope and Use of Illuminations Techniques

The gemological microscope is an essential tool in gemology as it allows gemologists to observe gemstones at high magnification, revealing their internal features and characteristics. Here are some key points about the gemological microscope and its various illumination techniques:

Features of the Gem Microscope

  • High magnification capabilities
  • Adjustable focus and zoom
  • Built-in light source
  • Ability to attach a camera for documentation purposes

Types of Illumination

  1. Reflected/Incident Illumination: This technique uses a light source positioned above the gemstone to illuminate it from different angles. It helps to reveal surface features, such as scratches and polishing marks.
  2. Dark Field Illumination: In this technique, the light source is positioned at an angle, causing the gemstone's facets to reflect light only when they have inclusions or defects. It enhances the visibility of internal features.
  3. Direct Light Field Illumination: This technique involves directing the light source straight through the gemstone, highlighting its transparency and internal characteristics.
  4. Diffused Illumination using White/Blue Filter: By using a white or blue filter, the gemologist can enhance or alter the color of the light passing through the gemstone, aiding in the identification of certain gem types.
  5. Polarized Illumination: Polarized light helps to identify and analyze the optical properties of gemstones, such as pleochroism and birefringence.
  6. Immersion: Immersion techniques involve immersing the gemstone in a liquid medium, such as refractive index liquids, to minimize the gemstone's brilliance and reveal its internal features more clearly.

Gemstone Inclusions and Types

Gemstone inclusions are natural or man-made materials trapped within a gemstone during its formation. They can provide valuable information about the gemstone's origin, formation process, and authenticity. Here are some common types of gemstone inclusions:

  • Fluid Inclusions: Small pockets of liquid trapped within the gemstone, which can contain water, gas, or other volatile substances.
  • Crystal Inclusions: Solid mineral crystals that are enclosed within the gemstone and can vary in size, shape, and color.
  • Needle Inclusions: Long, thin, needle-like structures that can be transparent, colored, or metallic.
  • Feather Inclusions: Cracks or fractures within the gemstone that resemble feathers, often caused by stress during the gemstone's formation.
  • Gas Inclusions: Tiny bubbles of gas trapped within the gemstone, which can affect its transparency and overall appearance.
  • Mineral Inclusions: Small mineral grains embedded within the gemstone, which can help identify the gemstone's type and origin.

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