Collecting & preserving sponges
Sponguide: Queensland Museum guide to sponge collection and identification (156 KB) describes detailed methods for collection, preservation, histological preparation and identification of sponges.
Toxic sponge Biemna hartmani, whose mucus produces severe burning sensation on contact with skin. Sponge expedition in northern Australia, with diver Dr John Hooper, undertaking video transects of a coral reef.You should collect sponges with care as many specimens are fragile and will disintegrate upon collection. Many species also have sharp spicules and toxic chemicals that may injure you.
We recommend you take underwater photographs of living specimens, given that body shape and colouration may change dramatically following preservation. Freezing specimens before they are preserved may help protect some of the pigments in colourful species, but often these are soluble and disappear into the preservative fluid.
Sponges are usually preserved separately in 70-80% ethanol. Take care to prevent contamination of pigments between samples, especially those species that turn black or dark blue upon exposure to air 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, including:
- nitric acid or chlorine bleach digestion of the silica and calcitic spicule skeletons respectively
- hand-cut or microtome cut sections of the whole skeleton (including details of the ectosome and choanosome)
- staining for different cellular elements
- scanning electron microscopy is now widely used.
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