- 7 - DESCRIPTION OF SPECIES

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Camron Haynes
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I - 7 - DESCRIPTION OF SPECIES./' Anguilla bicolor McClelland ' Level-finned eel (Figs.i & 2) Length of head 6-8 times in length of body; Diameter of eye 8-10 times, Inter-orbital length 2-2.

1 I DESCRIPTION OF SPECIES./' Anguilla bicolor McClelland ' Level-finned eel (Figs.i & 2) Length of head 6-8 times in length of body; Diameter of eye 8-10 times, Inter-orbital length times, Gape of mouth 3-4 times and Pectorals 2 times in length of 'head. Height times in length of bo~y and Length of head and trunk 1 1/2 times in length of tail. Body sub-cylindrical anteriorly and laterally compressed posteriorly; anus in anterior half of total lerigth; head flat; vertex well defined; posterior nostrils in front of eyes; anterior nostrils tubular and near antar~or margin of snout; eyes covered by skin and devoid of free orbital margin; cleft of mouth extends slightly behind eyes; lips thick; gill-openings vertical slits in front of pectoral fins. Teeth small and arranged in bands on jaws and vomer; maxillary teeth in broad lanceolate bands, closely connected to similar teeth on ~.vomer; mandibular teeth in,thick bands with tapering posterior ends; tongue free and branchial openings in pharynx wide slits. Pectorals well developed; pelvics absent; dorsal fin originates at the level of anus; dorsal, anal and caudal fins confluent.

I - 8 - Small cycloid scales present allover body; scales embedded in skin and not overlapping; colour brown on dorsal and lateral sides and yellowish white on ventral side; nasal tubes yellow;

2 I Small cycloid scales present allover body; scales embedded in skin and not overlapping; colour brown on dorsal and lateral sides and yellowish white on ventral side; nasal tubes yellow; pecto~ls transparent. Specim~ns reared in the Trivandrum aquarium attained a maximum length of 100 ems. Pisoodonophis boro (Ham. Buch.) Snake eel (Figs. 3 & 4) Length of head times in length of body; Diameter of eye times, Inter-orbital length 5-6" times, Gape of mouth 4 times and Pectorals 4 times in length of head. Height times in length of body and Head and trunk 1 1/2 times in length of tail. Elongate and cylindrical eels; tail much longer than length of trunk; skin devoid of scales; snout long, pointed and projecting beyond lower jaw; clef7pf mouth reaches posterior margin of eyes; eyes small and covered by a thick and transparent integument; posterior nostrils slit-like, on inner side of upper lip; anterior nostrils tubular, on ventral side of upper jaw close to snout. Teeth granular, arranged in several series forming bands on maxilla and dentary; tongue not free from floor of buccal cavity; branchial openings wide slits. Dorsal fin low and starts just behind level of posterior margin of pectoral fin; dorsal and anal fins not

- 9 - confluent; caudal absent; tail ends in a more or less sharp point; pectoral fins'well developed and pelvic fins, absent; both dorsal and anal fins supported by unbranched, bony rays; both fins

3 - 9 - confluent; caudal absent; tail ends in a more or less sharp point; pectoral fins'well developed and pelvic fins, absent; both dorsal and anal fins supported by unbranched, bony rays; both fins fold into shallow grooves of body. Colour dark brown with a blackish tint 'on dorsal and lateral sides and light yellow on ventral side; lateral region with numerous minute black spots. It reaches,a length of 80 ems.' Synbranchus bengalensis (McClelland) Blind or Pigmy eel (Figs.5, 6 & 7) Length of head times in length of body; Diameter of eye times, Inter-orbital length 6-7 times and Gape of mouth 3 times in length of head. Height times in length of body and I Length of tail 4 times in length of head and trunk. Body elongate and cylindrical with short and tapering tail; anterior nostrils minute and open on tip of snout; p08teria~nostrilsoval, situated in front of eyes; eyes small and covered by skin; lips thin; opercular openings united and free from isthmus; opercular opening single, narrow, median ventral and not extending to the sides. Teeth in upper jaw small, pointed and not continuous at, symphysis; mandibular teeth comparatively large and arranged in a single row along lateral sides; a gap in lower jaw between teeth on either sides; teeth on pa~atine arranged'in a single band.

- 10 - Dorsal and anal fins represented by' dermal folds devoid of fin-rays; anal fin commences,from behind anus and dorsal fin arises at a level slightly anterior to it; caudal ~in hardly

4 Dorsal and anal fins represented by' dermal folds devoid of fin-rays; anal fin commences,from behind anus and dorsal fin arises at a level slightly anterior to it; caudal ~in hardly conspicuous and supported by a few unbranched rays; paired fins completely absent. Colour dark brown on dorsal and lateral sides and yellow on ventral side or uniform light brown with dark brown spots on the dorsal and lateral sides. Maximum length 50 ems. Amphipnous fossorius Nair (Figs. 8 & 9) Length of head 9-10 times in length of body; Diameter of eye times, Inter-orbital length 5-6 times and Gape of mouth 3-4 times in length of head. Height times in length of body and Length of tail 4-4 1/2 times in length of head and trunk. Body elongate and cylindrical with scales in caudal region only; snout pointed; eyes in front of gape of mouth; anterior nostrils close to snout and posterior nostrils in front of eyes; upper Jaw slightly longer than lower jaw; opercular membrane extending over isthmus but not fused with it; opercular opening median ventral and transverse; region just behind head inflated by presence of air-sacs on either side. Teeth borne on maxillae, premaxillae and palatines; maxillary teeth short, recurved and set in two or three rows at anterior end but posteriorly cpnverge to a single row; only a single row of teeth on palatine; gills

( - 11 - devoid of gill filaments and skin~folds without rays.

5 ( devoid of gill filaments and skin~folds without rays. Dorsal fin commences from behind level of anus and confluent with a reduced caudal and a short anal fino Colour brown on dorsal and lateral sides and pale white on ventral side; caudal region often assumes a reddish tinge when specimens are exposed to air. Maximum length 23 cms. Several species of eels and eel-like fishes are found in the tropical region in about two-thirds of the earth~s circumference, comprising the coasts of the Indian Ocean from Africa to Australia and the Pacific Ocean as far as Tahiti. The four species selected for the present study are inhabitants of the swamps and marshes of Kerala coast. Anguilla and Pisoodonophis migrate into the sea and are therefore distributed in all the coastal regions of the tropics between Africa and Tahiti. The genus Synbranchus occurs in the tropical marshes of South America, Africa, India, East Indies, Philippines and 'Western Australia and provides a good instance of discontinuous distribution. Amphipnous fossorius has so far been recorded only from the coastal areas of Kerala. The closely allied species Amphipnous cuchia (Ham. Buch.) inhabits the marshy areas of Bengal and Burma.

-8- spinous. nape caudal fin. body depth. pectoral fin. anus. total length Fig. 4

-8- spinous. nape caudal fin. body depth. pectoral fin. anus. total length Fig. 4 click for previous page -8-1.3 Illustrated Glossary of Technical Terms and Measurements External Morphology and Measurements spinous dorsal fin soft nape caudal fin interorbital body depth snout lateral