RESULTADOS DE LAS OBSERVACIONES

8.1. Introduction

Like any learning process, naming sponges is likely to involve some mistakes on the part of those who are developing an interest in the group. Sponge identification is difficult; the highly variable nature of the growth patterns and the subtle distinctions between certain species dictate that utmost care must be exercised when arriving at the name of a sponge. This is especially so if the name is to be used in a survey report or a published work. Before embarking on an identification, the following “inputs” are required - the specimen, slide preparation(s), photograph(s), recorded information, a microscope, and literature.

8.2 Microscopy

For the examination of the slide preparation, a compound microscope is required. The more modern (and expensive!) mod- els found in institutions tend to be relatively easy to use, having an integral light source, and binocular eyepieces. A range of magnifications from 40x to 400x is ideal. Those with access to the older style traditional compound microscopes could consult White, 1978 for guidance on use. This is available in booklet form, as a reprint, from The Quekett Microscopical Club, c/o British Museum (Natural History), Cromwell Road, London SW7 5BD. Also, there are many general books on microscopy (e.g. Hartley, 1979) that provide useful introductions to the subject.

8.3. Literature

Unfortunately, the literature of potential relevance to the identification of British sponges is voluminous, widespread, and often difficult to obtain. Two starting points are the bibliographies of Vosmaer (1928) and the Porifera and Archaeocyatha section of The Zoological Record. The latter is now published by BIOSIS, 21OO Arch Street, Philadelphia, Pennsylvania 191O3, USA. Systema Porifera (Hooper, J.N.A. & Van Soest, R.W.M. (eds) 2002. Systema Porifera. A guide to the classification of sponges. I-xix, 1-1708, i-xlviii. Kluwer Academic Publishers, New York.) is an invaluable guide to sponge classification to genus level. Another useful reference is Sponges of the North East Atlantic (World Biodiversity Database CD-ROM Series) Authors: R.W.M. van Soest, B. Picton & C. Morrow. Publisher ETI. This taxonomic reference work was made by Rob van Soest, Zoological Museum, University of Amsterdam and Bernard Picton and Christine Morrow, Ulster Museum, Belfast. It is a unique, comprehensive guide to shallow-water sponges occurring in the coastal waters of Western Europe between the Arctic and southern Portugal. The CD-ROM contains up-to-date information on 337 shallow-water sponges, including a fully illustrated multiple-entry key, text key and interactive distribution maps. All text is hyperlinked.

The principal authors producing work relevant to British sponges are (or were!): W. Arndt, J.S. Bowerbank, M. Burton, L. Cabioch, C. Lévi, E.O. Schmidt, J. Stephens and E. Topsent. The two main monographic works are Arndt (1935) and Bowerbank (1864-1882). However, neither are particularly easy to use, and both are taxonomically out of date, and mis- leading in places. Arndt is written in German, concentrating on spicule characters, and having no illustrations of skeletons or specimens. Bowerbank uses an obsolete form of language for spicules, and of necessity concentrates his description on

TECHNIQUES

preserved rather than living material.

Those works that concentrate on specific taxonomic groups (e.g. Lévi, 1960; Topsent, 1900 and 1924), or sponges from a particular area (e.g. Burton, 1930; Cabioch, 1968) tend to be more helpful. Some references to these, as well as to papers dealing with individual genera or species, will be found on the species sheets. There is a bibliography of useful references at the end of this publication.

Marine faunas can provide good starting points, acting as check lists for sponges present in an area, as well as providing literature references. Three such are the Plymouth Marine Fauna (1957), the Roscoff Marine Fauna (Borojevic, Cabioch and Lévi, 1968, and the Lundy Marine Fauna (Hiscock, Stone & George, 1983[1984]). The latter includes non-technical descriptions of external form.

Literature can of course be consulted in the major reference libraries including the British Museum (Natural History), which runs a photocopying service (at a price!) Although it is not always apparent, some works are still in print. These, and second hand out of print works, can sometimes be obtained from specialist natural history booksellers such as Wheldon & Wesley Ltd., Lytton Lodge, Codicote, Hitchin, Herts, SG4 8TE.

The internet is becoming an invaluable source of new information on sponges. This guide is hosted at http://www.habitas. org.uk/marinelife/sponge_guide/ with additional species accounts and there is a world list of extant sponges at http://www. vliz.be/vmdcdata/porifera/. The latest developments in DNA barcoding of sponges can be found at http://www.spongebar- coding.org/.

8.4. Methods

Traditional methods of identification have centred on the skeleton and spicules, and descriptions of these are included in this Guide. The types, sizes, abundance, organisation and orientation of spicules on the surface, in the body, and at the base of the sponge are important. However, it is also important to use the living features and photographs, and to test their value when making an identification.

As a lead into the species sheets, the Table of Species Characteristics (next section) has been prepared, and should be con- sulted for clues by inexperienced users wishing to attempt an identification. Previous versions of this Guide have stated quite clearly that no reliance should be placed on any identification without microscopic examination. Whilst this still holds true, certain sponges can often be identified provisionally by sight alone, and these are indicated in the Table. Several other species can be recognised as being one of a pair. This phenomenon is rather curious, because the two species are not necessarily as close to each other taxonomically as they are to different species. The ‘pairs’ to watch out for are as follows:

Leucosolenia complicata - L. variabilis; Leuconia gossei - L. nivea; Suberites carnosus - S. domuncula; Polymastia bo- letiformis - P. mamillaris; Axinella damicornis - Stelligera rigida; Axinella infundibuliformis - Phakellia ventilabrum; Stelligera stuposa - Raspailia hispida; Halichondria bowerbanki - H. panicea (sublittoral form); Hemimycale columella - Phorbas fictitius.

It must be remembered that whilst all the commoner shallow water sponges are included in this Guide, it is by no means comprehensive. In many cases, particularly encrusting species, further literature will need to be consulted for an identifica- tion. If all else fails, the authors may be prepared to attempt identifications of limited amounts of material collected and curated to the standards outlined above.

9. HABITAT

The Marine Conservation Society, in association with the Nature Conservancy Council, has produced a comprehensive Sublittoral Habitat Record form. As noted below, many of the categories on this form are relevant when recording informa- tion about a single specimen. Indeed, data on the first three sections below need not be duplicated if a completed MCS form is available. However, information in the last two sections relates specifically to the sponge, and should be recorded. Each type of habitat data is categorized as Compulsory, Important, or Optional -hopefully self-explanatory terms.

Finally, one should not be constrained by the guidelines below. Information that cannot be predicted and/or categorized may be very important, and should be noted.

9.1. Site information

Site name (Important). Preferably use a name that appears on an Admiralty Chart, or 1:50,000 Ordnance Survey (O.S.) map.

For an offshore sublittoral site, a colloquial local name used by divers and/or fishermen may have to suffice.

Site number (Optional). In surveys such as those run by MCS, a site number is usually allocated. Survey area (Important). The general area - this must appear on either an Admiralty Chart or O.S. map.



O.S. grid reference, and/or latitude/longitude (Compulsory). Indicate source and datum - eg. GPS WGS84.