Fish Identification & Classification |
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In science, the term used to describe the diversity of life, identification and classification of animals and plants is known as systematics. Systematics encompasses taxonomy and is involved in reconstructing phylogenetic history. |
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Do you think you could identify fish using a key? Click Here Would you like to try doing a fishy puzzle? (Choose run from disk) Click Here |
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| THE SCIENCE OF SYSTEMATIC BIOLOGY
Systematics biology, or simply systematics, is the study of biological diversity. There are three major steps in studying the diversity of organisms: 1. Discovering, classifying and naming taxa, also referred to as TAXONOMY. 2. Investigating the relationship among these taxa, called PHYLOGENETICS 3. Creating meaningful biological classifications Taxonomy - The theory and practice of classifying organisms Phylogenetics - Inferring the evolutionary history of taxa Biological Classification - a hierarchical biological information system, for example -
What do systematists work with? The unit systematists work with is called the Taxon (taxa in plural). The taxon represents a grouping of closely related entities, be they individuals (i.e. a subspecies or a species), several species (i.e. a genus), several genera (i.e. a family), etc. Therefore the lowest taxon includes individuals and higher taxa include subordinate taxa and individuals. Once discovered, taxa are described using Characters. These are any attributes of a taxon that can be used for recognising, defining or differentiating it from other taxa. The most frequently used characters are morphological, osteological and anatomical ones. Behavioral, ecological, physiological, and molecular characters are used less frequently. How do they do it? Modern systematics is based on Darwin's discovery that evolution is a process of descent with modification. A more appropriate name is therefore phylogenetic (=evolutionary) systematics. Depending on the taxon investigated, a systematist may go through all three steps before completing the research. Discovering new taxa may happen through new collections and through taxonomic research (i.e. taxon based reviews and revisions, and regional reviews), and it involves the process of identification (i.e. using existing classifications and keys). Describing taxa consists of: (1) studying various attributes of the taxon in search of DIAGNOSTIC characters as well as characters it SHARES with related members of its group, and (2) formally publishing a description of the diagnostic characters with the name of the taxon. Naming a taxon is more than simply giving it a name. Before a name is accepted (i.e. published) it has to comply with the rules of the International Code of Zoological Nomenclature. Nomenclature is a system of names, and the provisions for their formation and use. The starting point of zoological nomenclature was arbitrarily set to 1 January 1758. This is the date of publication of the famous Swedish botanist Carl Linnaeus' Systema Naturae 10th edition. Linnaeus was the scientist who introduced the basic classification model and the binominal naming still in use today. Binominal nomenclature is a system of nomenclature whereby a species, but no other taxon, is denoted by a combination of two names (i.e. binomen), the first being the generic name and the second the specific name; interpolated names (i.e. subgenus and subspecies) are not counted as words of binomen. When taxa are described and named systematists proceed to investigate relationships between them. One of the most significant discoveries made in biology over the last 200 years is that all life forms on Earth are a result of evolution. Looking at this statement from the phylogenetic point of view one can say that all life is connected in an enormous phylogenetic tree. Systematists attempt to reconstruct this tree and uncover the patterns that led to the distribution and diversity of life as we know it. This is done through comparative biology. All comparisons, biological or not, deal with similarities. Systematists group individuals and taxa by looking at similarities emanating from a common genetic origin. When two species have similar characters inherited from a common ancestor these features are homologous. Using homologies systematists discover pairs of taxa, or sister taxa, that share a common ancestor. Individuals or taxa that do not conform with a group are excluded by default. The result of this process is a phylogenetic tree followed by a classification. What do we get out of it? The importance of this discipline is obvious. For example, outside the realm of science people of all cultures are interested in the question: where did we come from and what is our future? This question also concerns the basis of religion and hot debates between the creationist and the evolutionist doctrines and their implications on our lives. While the answer to the second part of this question may never be found, answering the first part will not be possible without systematics. In science, systematics forms the basis of all other fields of comparative biology: * It provides the framework (i.e. classification) and language (i.e. nomenclature) by which biologists communicate information about organisms. * Through phylogenetic hypotheses it provides the basis for evolutionary interpretations (e.g. modes of speciation, historical biogeography; historical ecology) * Phylogenetic hypotheses and corresponding classifications predict properties of newly discovered or poorly known (e.g. fossils) organisms Back to top of Page |
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SORTING AND IDENTIFICATION OF FISHES Below is a guide to how you can sort and identify freshwater fish of southern Africa and at the bottom of this article are two specimens for you to try and identify. Should you want to identify seawater fish you would need to use the book "Smiths Sea Fishes" by Smith & Heemstra. Check your programme for courses in fish identification being held by the JLB Smith Institute during Sci-Fest 2000. Below is the procedure I follow when identifying southern African freshwater fishes. I use Paul Skelton’s ‘A Complete Guide to the Freshwater Fishes of Southern Africa’ (1993). Usually I receive samples with more than one species and they are usually accompanied with information about who collected them and how, where and when they were collected which can help with identification. 1. Check labels and documentation in the sample bottle. Transcribe information onto a new label if necessary and also into your note book. Never throw original labels away. 2. Remove large specimens from the bottle and pour the liquid and remaining samples through a sieve. Wash quickly in water. Do not soak the sample in water. 3. Sort the sample out into species groups of fishes, invertebrates, plant material and any unidentifiable non-fish material. 4. Sort the fishes into groups on the basis of overall body shape, colour patterns and any other useful identifying characteristics. 5. All non-fish material can be placed into a single bottle and later sent to other specialists for identification (e.g. Albany Museum, Invertebrate Section). 6. Place each of the groups of fishes into separate bottles of 60% propyl alcohol. Don’t let fish dry out during the process of examination and try not to damage specimens during examination - they are valuable! 7. Copy the original label so that each new bottle has the full information about the samples. 8. Write labels and notes in your book clearly so that others can read your writing. 9. Identify fishes using keys in Skelton’s guide starting with the family key on pages 81-86. Keys are usually a series of questions with either/or options. Sometimes there may be three rather than two options. After you decide which option is correct for your fish you will either be directed to another question or arrive at a result - the name of the family. 10. When starting to identify fishes it is a good idea to write down the answers to the questions in the key. Take a new piece of paper for each new species. List the details of the sample at the top of the page e.g. date and place of collection and other details on the sample label. You may also wish to indicate in your notes where you are not sure of a question. This can help if you do not identify the fish correctly and need to go through the key again. 11. Some information on fish features, which can help you answer the questions in the keys, can be found on pages 19-34 and 65-67 in Skelton’s guide. 12. Once you have reached an end point the key will direct you to a page number where the family is found. 13. Read the information about the family to verify that you have correctly determined the family for the species you are examining. If you think you are wrong at this stage then you need to return to the family key to try to find out where you went wrong. Work through the key again. 14. Where the family is a small one there may not be a key e.g. page 354, family Sygnathidae (pipefishes). There are only two species in this family in southern Africa so there is no key. You must read the descriptions of the two species to match your species with one of the descriptions. 15. There may be a key which leads to families (catfishes, page 210), genera (Cyprinidae, page 117-119) or species (freshwater eels, page 104-105). Follow these through in the same way as you have in the family key until you reach an end point. 16. When you reach an end point to the species key go to the relevant page in the book and verify you have correctly identified the fish. This is done by checking the following.
If all the above verify you have correctly identified the fish - well done. 17. Note any small differences between your specimen and the description, colour pattern and distribution as noted in Skelton. Write them in your note book. 18. If you are not satisfied your identification you must go back to the keys. How far do you go back? Look at your notes to see where there were doubtful answers to determine where you start.
NOTES WHEN USING KEYS Clearly worded couplets Some couplets are easy to use as they give only one option e.g. 1 (page 81): 1a. Five pairs of gill slits 2 1b. One pair of gill slits 3
Complex questions Other couplets are more complicated as there are several possible features that can be used in identifying where next to go in the key e.g. 16 (page 83):
There are several problems with this example. a) What does small mean? That is not obvious without experience. b) What if the fish has 16 branched rays in the anal fin - which option do you choose? c) If the caudal fin is partly covered with scales do you choose 16a or 16b? The following sections will hopefully help you work through these kinds of problems.
Words you don't understand. An example is ...Jaws extended or not extended (20a/b, page 84). What does that mean? Of course you can ask an expert but one will not always be available. You can find out what this means on your own by following the key through to an end point and then examine the species for the particular feature. If we do this the couplet with jaws extended takes you to the family Hepsetidae (African Pike) on page number 208. Looking at page 208 you will find out that there is only one species in the family and there is a clear drawing of its unusual jaws with the upper jaw protruding or extended forward over the lower jaw. Does your fish have extended jaws? Using the same principle for the example above A16a .... gill slits small... takes us to page 92 the Mormyridae or elephant snout fishes. If you look carefully at the pictures of these fishes you will see the lower part of their gill opening stop somewhere near the pectoral fins. If you take A16b ... gill slits extended...then this takes you to 17 and 17a the Distichodontidae or citharines on page 193. These fishes gill slits extend onto the bottom of the head which is the typical of most fishes.
Overlapping features. Examples are - mouth inferior or mouth variable, - scales very small or scales variable but seldom small. Can these help you? In some instances features may be only partly overlapping e.g. a) lateral line scales 31-35 or b) scales 31-33. In this case if your specimen has 31-33 scales then you cannot distinguish between the two. If the specimen has 34-35 scales you can choose option a. Generally, overlapping features are problematic and if possible you should concentrate on features which show clear differences.
Unhelpful features in the key. Keys are man-made and so are not perfect. Some will ask questions which just don't help you find a solution e.g. (see from above) 16a. ...caudal lobes partly or largely covered with scales. In option 16b there is no mention of caudal (tail) fin scales. So what can you do? This feature does not help so ignore it. Concentrate on the other sections of the question. If you find other difficulties using keys let us know at e-mail: R.Bills@ru.ac.za or telephone the JLB Smith Institute of Ichthyology. Click here to have a look at a labeled drawing of a fish to help you with your identification The fish family key from Paul Skelton's - A Complete Guide to the Freshwater Fishes of Southern Africa (1993) are provided as well as some preserved specimens. Try using this to identify the fishes in the following pictures. The answers will appear when you place your cursor over the small pictures at the bottom so don't peek!
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| Place your mouse cursor over the fish below and
check your answers from the text boxes
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IF YOU WOULD LIKE TO LEARN MORE ABOUT FISH IDENTIFICATION WHY NOT ATTEND ONE OF THE COURSES BEING GIVEN BY THE JLB SMITH INSTITUTE DURING SCI-FEST 2000. CHECK YOUR SCI-FEST PROGRAMME FOR DETAILS.
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| Divers Assist Scientists in The East Coast Fish-Watch Project (ECFWP) is an exciting biodiversity initiative of scuba divers, anglers and scientists working together to learn more about fishes. The brainchild of Dr Phil Heemstra, the Curator of Marine Fishes at the JLB Smith Institute of Ichthyology in Grahamstown, the project was officially launched in August 1998 at Umkomaas on the Natal South Coast. This biodiversity initiative is supported by the JLB Smith Institute of Ichthyology (JLBSI), the Department of Ichthyology and Fisheries Science of Rhodes University (DIFS) and the Sea World Education Centre in Durban. Although smooth bottom habitats over the continental shelf in deeper waters have been fairly well sampled with gear such as trawl nets, the fish fauna of deep reefs and rocky areas is difficult to sample and poorly known. Despite the lack of a concerted collecting programme, in the past twenty years at least one hundred new species of marine fishes have been found in our area and numerous new records of species not previously known from this region are discovered every year. These recent discoveries indicate that our fish fauna is still poorly known. It is essential for the conservation of our marine fishes that we know what we have and where it is. A comprehensive survey of the fish fauna from the shore out to 200 metres depth will produce many valuable specimens and much information of use to the management of marine fish resources. In order to improve our knowledge of all fish species to be found in this area, Heemstra developed the ECFWP which comprises three complementary and synergistic components:
SCUBA diver participation and education The ECFWP is designed to bring the interested South African SCUBA diving community directly in contact with ichthyologists in a reciprocal teaching/learning relationship in order to improve the fish identification skills of everyone concerned. "The East Coast Fish-Watch Project has the potential to open a new world of learning and appreciation of our marine fish diversity to divers, anglers and aquarists," says Dr Heemstra. "With their active participation, members of the Project will learn much about fishes and develop new skills of observation and a better understanding of our rich marine fish fauna and the ecosystem of which it is a major component. And this understanding and appreciation are essential to the protection and sustainable use of our marine resources. By providing a purpose for SCUBA diving, the Project will also stimulate the SCUBA diving and related ecotourism industries," he says. "We therefore invite all divers and dive tour operators who are interested in participating in this project to contact us." The Fish-Watch dives are open-ocean training sessions in fish identification that are offered by approved dive charter operators. The dives are coordinated by the charter boat skipper or Dive Master who presents a short pre-dive briefing to provide some fish observation focus for that particular dive. For basic fish identification, the divers choose a particular family for example butterflyfishes, or genus of fishes that will be the focus of their dive. Alternatively the divers can pick a particular site or ecological category of fishes, for example demersal (sedentary) fishes, or pelagic (free-swimming) fishes, as the focus for the dive. After the dive, the Dive Master will lead a debriefing session on shore to discuss what was seen and learned on the dive. Typical questions are: which species were observed or identified, which fishes were seen but not recognised and which species were common or rare. Laminated waterproof worksheets identifying different species of fish have been produced and successfully tested on Fish-Watch dives. These include worksheet No. 1 on Butterflyfishes, No. 2 on Angelfishes and No. 3 on South African Reef Fish.
Participation in the Project is enormously beneficial for SCUBA divers as the dives become so much more meaningful and purpose orientated. This was brought home by a letter received from one of the participants, Pierre van Eeden who wrote, "Just a short note to say thank you for allowing us to take part in the East Coast Fish-Watch. I can’t get over the fact that diving with a purpose is now much more fun that what it used to be. I have always made it a goal to try and look for different species while diving, but never to be as specific as what it was this weekend. I actually feel sorry for the thousands of divers that go out diving ‘just to dive’". SCUBA divers can join the project for a nominal annual fee and in return will receive three underwater worksheets and three newsletters per year. The newsletter contains information on fishes and their identification as well as new records of fish species from the area. Members also receive reviews and notices of books and publications concerning fishes and progress reports on the fish survey work. Involvement of experienced underwater photographers is important to document new records of fish distribution, and to provide valuable photographs of colour pattern variation within species. Participating photographers are given free film and free membership in the Project in exchange for their contributions of fish photographs.
Survey of marine fish diversity Including deep sea fishes, the marine fish fauna of southern Africa comprises some 2,300 species or about 15% of all the marine fish species in the world. The goal of this survey is to discover, describe and classify all the fishes in the South African region. The inventory of marine fish diversity that will be produced by our survey work is an essential first step in understanding this diversity and the ecosystem of which it is a major component. This inventory is also necessary to determine and monitor distributions of the various species in our area. This information will be vital to the preservation of threatened ecosystems within the region. The faunal survey work provides an excellent opportunity for on-the-job training in the collection, identification and photography of fishes for divers, students and biologists.
Creation of a computerised East Coast FishBase Information provided by the fish diversity survey will be incorporated in a GIS (Geographic Information System) database. The East Coast FishBase is designed to
The long term goal of this project is to include colour images in the East Coast FishBase as well as information on the distribution, abundance, habitat, biology, size and commercial importance for each species. The East Coast FishBase could also include a video clip showing interesting behaviour of a fish and a sound clip giving the pronunciation of the fish’s scientific name and any sounds that this species might produce.
Progress The value and potential of Fish-Watch dives and the Project to diver education, appreciation of fish diversity and awareness of science is becoming more apparent as the Project develops. More than one hundred and thirty members have joined the Project and the benefits to each diver will increase as a corp of enthusiastic members grows and shares in the teaching/learning about fishes with one another. The Project has also facilitated the fish survey work. During the past twelve months several new records (fishes not previously known from the east coast region) of moray eels, pseudochromids, cardinal fishes, fusiliers, damselfishes, wrasses, gobies, soles, triggerfishes and pufferfishes have been discovered. To Heemstra’s delight, several new species have also been found and are yet to be described scientifically.
Funding SAPPI, the major sponsor, has generously provided funds for most of the running costs of the Project, but in order for the Project to grow and realise its full potential, additional funds will be needed for:
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| To join the East Coast FishWatch Project, please contact: Dr Phil Heemstra Curator of Marine Fishes JLB Smith Institute of Ichthyology Private Bag 1015 Grahamstown 6140 Tel: (046) 636 1002 Fax: (046) 622 2403 Email: P.Heemstra@ru.ac.za Or his research assistant, Mrs Joan Wright at J.E.Wright@ru.ac.za
Workshops on Fish Identification are conducted by: The Manager Education Centre Sea World P O Box 10712 Marine Parade 4056 Tel: (031) 337 3536 Fax: (031) 337 2132 |
For more information on FishWatch Dives, please contact: Mark or Michele Addison Blue Wilderness Dive Expeditions 21 Elizabeth Street Umkomaas 4170 Tel & Fax: (0323) 973 2348 Email: blue.wild@sco.eastcoast.co.za
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George Forder Spindrift Diving & Alternate Travel P O Box 13280 Cascades 3202 Tel & Fax: (0331) 42 9494 |
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