Biology Reference
In-Depth Information
by Nelson (2006). This scheme proposes that Elopomorpha is subdivided
into four orders: Elopiformes (tenpounders and tarpons), Albuliformes
(bonefi shes, halosaurs and spiny eels), Anguilliformes (various eels), and
Saccopharyngiformes (sackpharynx fi shes). In total, 24 families, 156 genera,
and about 856 species have been nominated in the Elopomorpha (Table
1). All but six species are marine, or primarily marine, species (Nelson,
2006).
Table 1.
The four orders of the Elopomorpha and numbers of families, genera, and species in
each order (after Nelson, 2006).
Order
Families
Genera
Species
Elopiformens
2
2
8
Albuliformes
3
8
30
Anguilliformes
15
141
791
Saccopharyngiformes
4
5
28
3.3 Morphological Features of Leptocephali
3.3.1 General features
Photographs of leptocephalus larvae of the Japanese eel are shown in
Fig. 2 and drawings of various types of leptocephali are illustrated in Fig.
3. The body is laterally-compressed, leaf-like and transparent, which is
considered to be adaptive to a planktonic life in the ocean. A large quantity of
Figure 2.
Leptocephalus of the Japanese eel (
Anguilla japonica
). (a) Late stage of wild
leptocephalus (60 mm in total length) captured in the Pacifi c Ocean east of Okinawa Islands.
The specimen was preserved in 10% formalin and was a gift from Dr. Kurogi. (b) The head of
a live leptocephalus reared in an aquarium from a fertilized egg; donated by Dr. Tanaka.
