BONY FISHES TECHNICAL TERMS

Transcription

1 previous page 1 TECHNICAL TERMS Principal Measurements Used (shortest distance between the points marked) preorbital length head length eye standard length postorbital length 1st dorsal fin base total length interdorsal space 2nd dorsal fin base depth of 2nd dorsal fin fork length length of caudal peduncle depth of body length of pectoral fin anal fin base upper jaw General Nomenclature of the External Morphology opercle 1st dorsal fin nos- trils pre preopercle opercular membrane nape 2nd dorsal fin caudal fin (upper lobe) chin suborbital plate branchiostegal rays lateral line anus caudal peduncle caudal fin (lower lobe) inter opercle subopercle pectoral fin anal fin pelvic fin

2 2 Details (all schematic examples) molar-like incisor-like terminal subterminal inferior retracted protrusible canine-like cardiform protracted mouth spines (unsegmented, always unbranched) soft rays (segmented, usually branched adipose fin finlets example of a continuous dorsal fin of a spiny-rayed fish gill arch (upper part) margin smooth margin spiny gill filaments cycloid ctenoid gilirakers gill arch (lower part) schematic examples of "normal" scales first left gill arch rounded truncate emarginate lunate forked pointed most common types of caudal fin pointed and separated from the dorsal and anal fins

3 3 GUIDE TO THE IDENTIFICATION OF FAMILIES OCCURRING IN THE GULF OF GUINEA The purpose of this guide is to ensure the correct identification of all families that may enter the catches in the Gulf of Guinea. in order to avoid erroneous identification, it was necessary to include also certain families of no interest to fisheries, but which might be confused with important ones. Apart from the identification of families, this guide often allows the identification of genera, some of which are illustrated in the case of high pteymorphic families. Note : Page numbers are given for those families that are treated in more detail. All features utilized in this guide apply only to species occurring in the Gulf of Guinea. TARPONS AND ALLIES - Elopiformes Fin-spines absent; a single-dorsal fin located above middle of body; pelvic fins in abdominal position; cteour silvery. ELOPIDAE Ladyfishes page 62 To 90 cm; coastal marine waters, estuaries and freshwater; mainly pelagic. MEGALOPIDAE Tarpons page 81 very small scales To 250 cm; in coastal marine waters, estuaries and freshwater; pelagic. A single species in the area. large scales large mouth Elops Tarpon atlanticus HERRINGS AND ALLIES - Clupeiformes Fin-spines absent; a single dorsal fin located above middle of body; pelvic fins in abdominal position; lateral line absent; a row of along ventral profile (except in Engraulididae); colour silvery. ALBULIDAE Bonefishes page 39 To 80 cm; mainly in coastal marine waters, sometimes entering estuaries; demersal. small scales short CLUPEIDAE Sardines, sardinellas, etc. page 57 To 60 cm, but most species less than 25 cm; in coastal marine waters, estuaries and freshwater; mainly pelagic. notch Albula vulpes long 2 supra e Pterothrissus belloci short Ethmalosa fimbriata

4 4 EELS - Anguilliformes Body very elongate; fin-spines absent; pelvic fins absent; usually scaleless. long CONGRIDAE Conger eels Ilisha africana To over 200 cm, but usually not exceeding 60 cm; marine, from the shore to about 2000 m depth; benthic. Several species taken occasionally. 1 supra gill slit buccal fold Pellonula leonensis pectoral fin present opercle smooth 2 fleshy flaps Snake eels, OPHICHTHIDAE snapper eels, page 87 worm eels To 245 cm; marine, from shallow coastal waters to below 750 m depth; occasionally in estuaries; most benthic, some pelagic. Several species occurring in catches. median pore 2 last rays longer Sardinella ENGRAULIDIDAE Anchovies page 63 on lip top of head To 12 cm; coastal marine waters, to 400 m depth; offbottom to pelagic. A single species in the area. pectoral fin present or absent no Engraulis encrasicolus Echelus other genera types of tail

5 5 MURAENESOCIDAE Pike congers page 85 conspicuous bands longer To 200 cm; marine, from shallow coastal waters to at least 200 m depth; benthic. A single species in the area. pectoral fins present upper tooth serrated, resembling those of sharks Gymnothorax maderensis Channomuraena vittata large gill slits MORINGUIDAE Spaghetti eels large along midline of palate To at least 50 cm; marine, mostly inshore waters; benthic (burrowing) by day, but pelagic at night; a strong sexual dimorphism. MURAENIDAE Morays page 85 projecting To over 200 cm; marine, from shallow coastal waters to beyond 500 m depth; benthic. nape region elevated pectoral fins absent juveniles and immature adults gill opening round mature adults both s jaws arched, always visible head elongate XENOCONGRIDAE False morays To about 50 cm; marine, from the shore to at least 350 m depth; benthic. Muraena lateral line pores restricted to head gill opening small, rounded Enchelycore nigricans blunt Iong and pointed post. inside mouth, on upper lip or just above mouth pectoral fins present or absent anterior anterior 2 widely diverging rows of vomerine Echidna peli Lycodontis on roof of mouth next page