CASTLE: NOTACANTHIFORMES. ANGUILLIFORMES 



67 



Table 11, Extended. 



Heleren- Myrocon- Xenocon- 



chelyidae Muraenidae gndae gridae 



Eury- 

 Ncmich- Sacco- pharyngj- Mono- 



thyidae Cyematidae pharyngidae dae gnathidae 



+? 



+? 



+? 



(+) 



+ 



+? 



+ 

 + 



+? 



somewhat resembles later stages but the development of larval 

 characters is progressive. There may be substantial differences 

 in pigmentation between this stage and the fully grown lepto- 

 cephalus (e.g.. the congrid Ariosoma, Table 17 E,, Mj, O and 

 Fig. 37); typically the pigmentation pattern is much less com- 

 plex. The engyodontic stage has few, needle-like teeth, lower 

 jaws equal to, or longer than upper, an unformed nasal capsule, 

 and undifferentiated median fin-folds and hypurals. 



At about 20 mm TL the leptocephalus then enters the eury- 

 odontic stage which lasts until metamorphosis. It begins with 

 shedding of the engyodontic teeth and their replacement by 3 

 series (usually) of shorter, broad-based teeth, the lower jaw 



shortens relative to the upper, the head decreases in relative 

 length, and the fins and hypurals differentiate. At this stage 

 leptocephali are highly distinctive and well-known forms amongst 

 fish larvae. At full growth they are typically around 50-80 mm 

 but may attain 300-400 mm (Nemichthyidae) or 1,800 mm 

 (Notacanthiformes). They are almost transparent except for eye 

 and other pigmentation and the blood lacks erythrocytes and 

 haemoglobin. The body is greatly compressed and leaf-shaped 

 or filamentous, typically with a small head, prominent, for- 

 wardly-directed larval teeth and a posteriorly placed anus. The 

 electrolyte make-up of their body fluids differs markedly from 

 that of postmetamorphic forms (Hulet, 1978). 



Table 12. Extended. 



2.40 

 3.00 

 1.44 

 1.48 



+ 



2.72 

 3.04 

 1.40 

 1.48 



-I- 



13 



0.04 

 0.08 



2.60 

 1.7 

 -I- 

 1 

 0.40 



1.80 

 1.92 

 1.00 

 1.04 



-I- 

 1 

 5 



0.30 



2.93 

 3.43 

 1.25 

 1.50 



-I- 

 1 

 9 



0.03 

 0.10 



2.50 

 3.00 

 1.50 

 1.85 



-t- 



5.0 

 5.5 



2.3 

 3.4 



3.3 

 4.0 

 1.5 

 2.0 



-I- 



2.3 

 2.9 

 1.3 

 1.6 



1 



2 



0.31 



0.42 



-I- 

 + 

 J 



+ 

 + 



+ 

 + 

 1 



+ 

 + 

 m 



+ 

 -I- 

 m 



-I- 

 -I- 

 -I- 

 n 



