Starfishes and Sea Urchins
Starfishes are commonly preserved by simply allowing them to dry in an airy place, with or without direct exposure to the sun’s rays, and this method is fairly satisfactory when the drying proceeds rapidly; but care should be taken to maintain the natural roughness of the exterior as well as to have the numerous suckers of the under surface as prominent as possible. If the starfish is simply laid out on some surface to dry, the side on which it rests is often more or less flattened by the weight of the specimen itself, which therefore becomes adapted for the future examination of one surface only; but a better result, as regards both the rapidity of drying and the after appearance of the specimen, may be obtained by suspending it on a piece of fine net or by threads. A still better plan is to put the dead starfish into strong spirit, which will rapidly extract the greater part of the moisture that its body contained. After allowing it to remain in this for a day or two to harden it, put it out to dry as before mentioned. The spirit, being very volatile, will soon evaporate, so that the specimen will shortly be ready for storing away.
It is most important to observe that dried specimens—not starfishes only, but all animal and vegetable objects—should never be placed in the cabinet or other store-case until perfectly dry, for a very small amount of moisture left in them will often encourage the development of moulds, not only on themselves, but on other specimens stored with them.
Very small and delicate starfishes, when preserved in a dry condition, may be protected from injury by fastening them on a card by means of a little gum, or by keeping them permanently stored on cotton wool in glass-topped boxes.
Sea urchins, or sea eggs, as they are commonly called, may be preserved exactly in the same way as starfishes, though it is more essential in the case of these to soak them in strong spirit previous to drying, otherwise the soft animal matter within the shell will decompose before the drying is complete. Here, however, it is possible to remove the whole interior with the aid of a piece of bent wire, and to thoroughly clean the inner surface of the shell before drying it.
Some of the shells should be preserved with the spines all intact, and others with these removed in order to show the arrangement of the plates which compose the shell, as well as the perforations, and the rounded processes to which the spines are articulated.
The majority of sea urchins are provided with a most complicated and beautiful arrangement of teeth which are well worthy of study. These should be removed from a moderately large specimen, the soft surrounding structures carefully dissected away, and then cleaned by means of an old tooth-brush without disarranging them.
It will be found that dried sea urchins will require care when preserved with spines attached, for these appendages are usually very brittle and are easily dislocated at their bases where they are united to the shell by ball-and-socket joints.
It may be mentioned here that corrosive sublimate is very valuable for preventing the development of mould on the surfaces of starfishes, sea urchins, and museum specimens generally. It is best supplied in the form of an alcoholic solution made by dissolving a few grains in about half a pint of methylated spirit; the advantage of this over an aqueous solution being the rapidity with which it dries. In most cases it is simply necessary to apply the solution to the object by means of a soft brush, but, as regards starfishes and urchins it is far better to dissolve a few grains of the corrosive sublimate in the spirit in which the objects are placed previous to drying.