NIAID Schistosomiasis Resource Center

Gel snail food preparation

Author Fred Lewis

Introduction

This gel preparation is an ideal supplement to the mud, algae (Nostoc) and lettuce that is normally fed to adult snails, particularly when Nostoc production is low. Snails 4 mm in diameter and larger will migrate to the gel and eat it vigorously. Snails less than 4 mm prefer the algae, so we do not recommend feeding the gel preparation to small snails.

Equipment

Electric stirring hot plate

1000 ml beaker

Large stirring bar (1.5 inch)

Thermometer

Mortar and pestle

Two flat plastic 7” x 9” x 6” pans

Materials and reagents

500 ml deionized water

8 g barley grass powder (available at health food stores)

2 g wheat germ (available at grocery stores)

2 g fish food (Tetramin – Large Tropical Flakes)

1 g powdered milk (available at grocery stores)

2 g sodium alginate (Alginic acid-sodium salt – Sigma A-2033, medium viscosity, sold as a fine powder)

1 liter 2% calcium chloride solution (Sigma C-4901, anhydrous)

Procedure

· Heat 500 ml deionized water to ~70-80°C in a 1000 ml beaker with a large stirring bar. Do not boil at any time, but continue to heat on the hot plate.

Add ingredients in the exact order listed above.

· Add 8 g barley grass powder to the hot water while stirring.

· Pulverize wheat germ, fish food and powdered milk to a fine powder in the mortar and pestle, then gradually add the powder to the barley grass suspension, continuing to heat and stir.

· After other ingredients are in suspension, add the sodium alginate very gradually. Most, but not all of the alginate will go into suspension; some alginate will form clumps, but these will not cause problems with the final product.

· Continue to stir for a few minutes.

· Pour the hot suspension into flat pans to cool to room temperature. For 500 ml of food, two 7”x 9”x 6” pans will provide adequate area for a ½” depth gel.

The suspension should not exceed ½ inch in depth. We use 2 plastic 7”x 9” plastic

mouse cages for cooling the suspension.

· Allow the suspension to cool at room temperature for 2-3 hours without disturbing the pans.

· After the suspension is cool and partially solidified, gently flood each pan with the 2% calcium chloride (CaCl₂)solution until the gel is well covered. In order not to disturb the gel, slowly pour the calcium chloride solution over a glass plate onto the surface of the gel.

· Place the pans in the refrigerator (4°C) overnight.

The gel will shrink after 2-3 hours in the cold CaCl₂.

· Pour off the CaCl_2,and rinse the gel 1-2 times with deionized water. The gel is now firm enough to hold with a gloved hand while rinsing.

· Store the remaining gel at 4°C in the 7”x 9”x 6” pan until use.

· The gel may be fed to snails by pinching off a section approximately 1”x 1” per 50 snails. Be careful not to overfeed the snails. If the gel is not cleared within a day or two, bacteria may begin to grow and foul the water.

Follow-up comments/recommendations

The gel snail food will be useable for about 1 week before it deteriorates. Any remaining gel should be disposed of and a new preparation made each week.

Reference(s)

Formula adapted from: Standen, O.D. 1951. Some observations upon the maintenance of Australorbis glabratus in the laboratory. Annals of Tropical Medicine and Parasitology 45: 80-83.

NIAID Schisto Resource Center __________ Home Species Ordering How to Order Ordering Mammals Contact Information Operating Procedures Introduction Standard Operating Procedures List of Contributors Links Questions
		Gel snail food preparation Author Fred Lewis Introduction This gel preparation is an ideal supplement to the mud, algae (Nostoc) and lettuce that is normally fed to adult snails, particularly when Nostoc production is low. Snails 4 mm in diameter and larger will migrate to the gel and eat it vigorously. Snails less than 4 mm prefer the algae, so we do not recommend feeding the gel preparation to small snails. Equipment Electric stirring hot plate 1000 ml beaker Large stirring bar (1.5 inch) Thermometer Mortar and pestle Two flat plastic 7” x 9” x 6” pans Materials and reagents 500 ml deionized water 8 g barley grass powder (available at health food stores) 2 g wheat germ (available at grocery stores) 2 g fish food (Tetramin – Large Tropical Flakes) 1 g powdered milk (available at grocery stores) 2 g sodium alginate (Alginic acid-sodium salt – Sigma A-2033, medium viscosity, sold as a fine powder) 1 liter 2% calcium chloride solution (Sigma C-4901, anhydrous) Procedure · Heat 500 ml deionized water to ~70-80°C in a 1000 ml beaker with a large stirring bar. Do not boil at any time, but continue to heat on the hot plate. Add ingredients in the exact order listed above. · Add 8 g barley grass powder to the hot water while stirring. · Pulverize wheat germ, fish food and powdered milk to a fine powder in the mortar and pestle, then gradually add the powder to the barley grass suspension, continuing to heat and stir. · After other ingredients are in suspension, add the sodium alginate very gradually. Most, but not all of the alginate will go into suspension; some alginate will form clumps, but these will not cause problems with the final product. · Continue to stir for a few minutes. · Pour the hot suspension into flat pans to cool to room temperature. For 500 ml of food, two 7”x 9”x 6” pans will provide adequate area for a ½” depth gel. The suspension should not exceed ½ inch in depth. We use 2 plastic 7”x 9” plastic mouse cages for cooling the suspension. · Allow the suspension to cool at room temperature for 2-3 hours without disturbing the pans. · After the suspension is cool and partially solidified, gently flood each pan with the 2% calcium chloride (CaCl₂)solution until the gel is well covered. In order not to disturb the gel, slowly pour the calcium chloride solution over a glass plate onto the surface of the gel. · Place the pans in the refrigerator (4°C) overnight. The gel will shrink after 2-3 hours in the cold CaCl₂. · Pour off the CaCl_2,and rinse the gel 1-2 times with deionized water. The gel is now firm enough to hold with a gloved hand while rinsing. · Store the remaining gel at 4°C in the 7”x 9”x 6” pan until use. · The gel may be fed to snails by pinching off a section approximately 1”x 1” per 50 snails. Be careful not to overfeed the snails. If the gel is not cleared within a day or two, bacteria may begin to grow and foul the water. Follow-up comments/recommendations The gel snail food will be useable for about 1 week before it deteriorates. Any remaining gel should be disposed of and a new preparation made each week. Reference(s) Formula adapted from: Standen, O.D. 1951. Some observations upon the maintenance of Australorbis glabratus in the laboratory. Annals of Tropical Medicine and Parasitology 45: 80-83.