Preservation And Identification

An information sheet on collecting, preserving, histo-logical preparation and lists of characters used for identification of sponges can be found on the web (see Additional reading). Collection of sponges within the Marine Park requires a permit and should also be undertaken with care (both for the sponge and the collector), owing to the often fragile nature of many specimens that disintegrate upon collection, and the sharp spicules and toxic mucus/chemicals that may injure the collector. Underwater and/or on-deck photographs of living specimens are highly recommended given that body shape and colouration may change dramatically following preservation. Freezing specimens prior to their preservation may be useful to fix soluble pigments in colourful species. Sponges are generally preserved separately in 70-80% ethanol, with care taken to prevent leaching of pigments between samples, particularly those with aerophobic pigments that change from yellow to blue and may stain entire collections. Formaldehyde preservative should be avoided for most sponges although it is used briefly as a fixative for calcareans, and air dried specimens are virtually useless for taxonomic identification. Other specialised fixatives include gluteraldehyde for detailed cellular ultrastructure studies (do not freeze), and 100% ethanol, DMSO or laboratory grade silica gel for storage of DNA samples. Routine histology is required for identification, and includes nitric acid or chlorine bleach digestion of the silica and calcitic spi-cule skeletons, respectively. Thin sections of the whole skeleton can be hand or microtome cut to include details of the ectosome and choanosome. Staining sections for different cellular elements and scanning electron microscopy are now widely used. Keys to orders, families and genera (see Additional reading) are largely based on features of the inorganic and organic skeletons.

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