Make a Collecting Syringe and Jar for Small Marine Invertebrates

Cut open the end of the syringe. Take care to leave a small flange to prevent the plunger being pushed out the end. This can be done using a hacksaw and a round file. The end of the syringe will probably be a flat cone with the needle nozzle offset to one side.

Cut off most of the cone and file the edges until the remaining flange is about 1mm wide all round. This is not a critical dimension. The syringe is now functional. A useful accessory is a small bungee lanyard which can be slipped over the wrist to prevent accidental loss.

Collection of small and delicate marine organisms can be facilitated by the use of a suction collector made from a large disposable syringe and a self closing plastic collection jar as described in this article.

Purchase a large disposable plastic syringe from a pharmacy. The 60ml size is suitable for many organisms and is easily available.

Purchase a screw top plastic jar of suitable size to store the organisms until they can be decanted.

Use the end of the syringe and a fine felt tip marker to mark the position for the hole in the lid of the jar. Be careful to put the hole fairly close to the side , but clear of the thread. The reason for this is to allow space for the spring-loaded flap closure.

Cut this hole using whatever tools you have that work best. A bell punch is quick but may not be available in the ideal size, but the hole can be filed to correct the size and shape. If all else fails, a carpet knife will do the job, bur cut undersize and file to a reasonably close fit for the syringe, which should enter the hole easily, but with small clearance all round.

Pierce a pair of small holes adjacent to the loading hole for the bungee spring which will close the flap. These may be drilled or pierced with a heated wire. These holes should be just beyond the edge of the loading hole to allow the syringe to push the flap open when inserted into the loading hole.

Pierce a few small holes in the far side of the lid to allow water to escape when transferring organisms from the syringe to the jar. These holes should be too small for the organisms to escape through them. 1mm to 2mm diameter is usually appropriate. Use as many as you find convenient. A large number of holes allows the transfer to be done faster.

Cut a small piece of flat plastic sheet for the flap. This must be stiff enough to remain flat. Pierce two holes to correspond with the bungee spring holes in the lid. The flap should be straight sided adjacent to the holes and parallel to the line between their centres. and should fit completely over the transfer hole, but clear the thread at the edge of the lid.

Thread a short length of thin (about 2mm) bungee cord (shock cord) through the holes in the lid and flap. Tie the ends to hold the flap in place on the underside of the lid. Ensure that the flap allows clearance for the jar to screw onto the lid.

Test the function of the flap by stainless flange fitting the lid to the jar and inserting the syring through the transfer hole. The flap should open into the jar and automatically close when the syringe is removed.