Guana Island Marine Invertebrates

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Sorting and Specimen

Preparation

Very little specimen preservation was done in the field. Collections were taken back to the lab within a few hours. There, a seawater based septic system system provided flowing seawater so that animals could be kept alive in makeshift water tables. Bubblers were used to increase oxygen.

Algal samples were sorted under dissecting microscopes, and specimens were immediately placed into small, lidded, plastic petri dishes. Bags full of coarse sand from push net samples were dumped into plastic washtubs from which specimens could be sorted. Larger specimens were placed into 8 oz plastic deli tubs with a small amount of water several like-sized animals could be kept together in this way.

Before specimens could be photographed, they were first relaxed and cleaned under a dissecting scope using forceps, and paint brushes whose bristles had been cut down to increase stiffness (the occasional large crab required a toothbrush). The following relaxants were used:

Relaxant	Animals
Magnesium Chloride (MgClx6H20): 72 grams of crystals per liter of fresh water creates an isotonic solution that affects muscle activity. Relaxed animals can be revived in clean water.	Best for echinoderms (Brittle stars and sea stars) that stiffen upon death. Some worms and sipunculans relax and evert their probosci, while others react violently.
Clove Oil : 4-5 drops per liter of sea water inhibits neural activity. Anesthetized animals can be revived in clean water. This is messy so it is a good idea to pass shaken water through a coffee filter to remove globules before use. Intense smell of cloves. Quickly eats through polystyrene (white deli tubs) on contact, clear polyethylene containers are safe.	Best for shrimp, whose tissue quickly becomes cloudy upon death. Some species do not react to MgCl quickly, but succumb to clove oil. Some soft bodied species react violently to it. Can also be used like a dilute formalin wash to loosen animals from mass samples of algae, rock etc.
Ice Place crustaceans in a dry bowl on ice to prevent bodies from swelling after death. Place other species in containers with a little water. Deli tubs work well in both cases.	Best for crabs and larger soft bodied animals. Especially those that react to violently to other means. Tropical species succumb quickly. Specimens were generally placed on ice last thing at night to be ready in the morning.

It is preferable to relax many organisms before preservation in order to prevent contraction of diagnostic body parts, or autonomization of limbs. The onset of rigor mortis makes positioning of crabs difficult just after death. Put then back on ice until the process is complete at which time limbs can be loosened and positioned.

 

Specimen Preservation

Worms and Microcrustaceans were generally placed straight into 2 ml cryo-vials with 5-10% formalin. Decapods were either placed into formalin for 1-2 days before transfer to alcohol, or straight into 75% ethanol (Cruzan brand 151 proof light rum). Larger specimens were slit along the back of the carapace Crabs) or the abdomen (hermits), or injected (echinoderms) to allow quick entry of the preservative. The larger specimens were preserved in plastic bags (or 1-2 oz Nalgene bottles), from which the preservative was drained befog shipping. Upon arrival home specimens were transferred to 70% ethanol (crustaceans and polychaetes) or 85 % ethanol (echinoderms). Mollusks were either preserved in ethanol, or shipped dry (sand samples) to preserve microarchitecture of their shells.