Preservation of arachnids is essential to maintain their structural integrity for scientific study and research. Different methods are used depending on the species, intended study type, and duration of preservation. Here are the most common techniques:
1. Alcohol Preservation
• Method: Most arachnids are best preserved in 70-80% ethanol.
o Use 95% ethanol initially if the specimen is fresh or contains a lot of body fluids, and then transfer it to 70-80% ethanol after 24-48 hours.
• Target Group: Suitable for most arachnids, including spiders, scorpions, mites, and ticks.
• Advantages: Alcohol preserves the soft tissues and prevents decay, making it the standard method for long-term preservation.
• Procedure: Place the specimen in a labeled vial filled with ethanol, ensuring that the container is tightly sealed to prevent evaporation.
2. Freezing
• Method: Some arachnids can be frozen for short-term preservation, especially if they are needed for molecular or DNA studies.
• Target Group: Effective for DNA and RNA analysis from tissues, including spiders, scorpions, and mites.
• Procedure: Place the arachnid in a small, airtight container or plastic bag and store it in a freezer.
• Advantages: Freezing preserves the genetic material without chemical interference, making it ideal for genetic studies.
3. Dry Preservation (Pinning and Mounting)
• Method: For large or display arachnids like tarantulas or scorpions, dry preservation methods like pinning or mounting can be used.
• Procedure:
o Tarantulas/Scorpions: Spread the legs in a natural position and let the specimen air-dry or use a desiccant.
o Smaller Arachnids: They can be pinned through the body or glued onto a card for display purposes.
• Target Group: Mainly used for large species or those intended for display.
• Disadvantages: Drying can cause some distortion or shrinkage of soft body parts.
4. Glycerin Storage
• Method: Small arachnids like mites can be stored in glycerin.
• Procedure: Soak the specimen in ethanol first to dehydrate it, then transfer it to a small vial containing glycerin.
• Advantages: Glycerin helps prevent desiccation and maintains the specimen’s flexibility.
5. Chemical Fixatives for Microscopy
• Method: If detailed histological or microscopic analysis is required, chemical fixatives like formalin or glutaraldehyde may be used to fix the tissues.
• Procedure: Immerse the specimen in a dilute formalin solution (4-10%) to fix its internal structures.
• Target Group: Used for scientific studies focusing on cellular or tissue-level analysis.
6. Clearing for Microscopic Studies
• Method: Small arachnids or parts of their anatomy may be cleared using chemicals like lactic acid or clove oil to make the tissues transparent for microscopic examination.
• Target Group: Mites, ticks, and small spider parts are commonly treated this way.
• Advantages: Clearing makes internal structures visible for identification and study under a microscope.
Best Practices for Arachnid Preservation
• Labeling: Always label each specimen with important information such as the date, location, habitat, collector’s name, and collection method.
• Sealed Containers: Ensure that the containers used for storing specimens are properly sealed to prevent evaporation of ethanol or glycerin.
• Avoid Sunlight: Store preserved specimens in a cool, dark place to avoid degradation caused by light and temperature changes.
• Periodic Checking: Regularly check the condition of preserved specimens to ensure that the ethanol level is sufficient and the specimen remains intact.
These preservation methods help maintain the morphological features of arachnids for future studies, ensuring that they remain useful for taxonomy, research, and educational purposes.