KENDALL ET AL.: ELH STAGES AND CHARACTERS 



13 



END POINT EVENTS 



TERMINOLOGY 



Primary developmental 

 stages 



Transitional stages 

 Subdivisions 



OTHER 

 TERMINOLOGIES 



Hubbs, 1943,1958 



Sette, 1943 



Nikolsky, 1963 



Hattori, 1970 



Balon, 1975 (phases) 



Snyder, 1976,1981 (phases) \ 



Yolk sac 

 larva 



Transforma 

 lion larva 



Pelagic or 



special juven 



Embryo 



Prelarva 



Fig. 6. Terminology of early life history stages. 



completely ossified, the larval pigment pattern is overgrown or 

 lost and replaced by dermal pigment similar to that of the adults, 

 and the body shape approximates that of the adults. 



Although this is the most frequently observed life history 

 pattern, there are many variations (see Breder and Rosen, 1 966) 

 often related to increased parental investment in individual 

 progeny with a concomitant decrease in fecundity and larval 

 specializations. There is scant information on the young of many 

 deep-sea fishes, and this may be due in part to life history 

 strategies that do not include eggs and larvae that occur in the 

 epipelagic zone (where most of the collecting is done). Marshall 

 (1953) discussed life history adaptations of these fish such as 

 the production of few, large yolky eggs that hatch into relatively 

 advanced larvae. These young may remain far below the more 

 productive surface layers, and thus not be susceptible to most 

 sampling procedures. Markle and Wenner (1979) cite evidence 

 for demersal spawning of two species of groups (Alepocephal- 

 idae, Zoarcidae) that are seldom collected in the plankton as 

 larvae. 



Many coastal marine and nearly all freshwater fishes lay de- 

 mersal eggs which are generally larger than the I mm mode of 

 pelagic eggs. In such fish development from hatching through 

 juvenile stage is direct and the larvae gradually attain adult 

 characters of shape, pigmentation, and meristic features. The 

 demersal eggs frequently are adhesive and laid in some sort of 

 nest. Parental care of the nest is observed in many species, and 

 this care may extend to the larvae after hatching (e.g., mouth 

 brooding in cichlids, ariids). Parental care takes another form 

 in Sehastes. where development through the yolk-sac stage takes 



place in the ovary and first-feeding larvae are extruded. Vivi- 

 parity, in which nourishment is supplied by maternal structures, 

 has evolved many times (e.g., poeciliids, some zoarcids, em- 

 biotocids), whereby the larval stage is bypassed and the fish are 

 extruded ("bom") as juveniles (Wourms, 1981). 



Early Life History Stages 



Between spawning and recruitment into the adult population, 

 most fishes undergo dramatic changes in morphology and hab- 



Table 2. Examples of Characters of Pelagic Eggs that May Be 

 Useful for Systematic Studies of Certain Fishes. 



Character slates 



Systematic groups 



Egg size 



Egg shape 



Envelope 

 sculpturing 



Oil globule 

 position 



Embryonic 

 characters 



< 1 mm->5 mm 

 >3 mm->5 mm 



Round — oblong 



Varying distances between 



pores 

 Varying length/density of 



filaments 



Anterior to posterior in 

 yolk sac 



Slate of development of 

 various organs/organ sys- 

 tems at various develop- 

 mental mileposts 



Pleuronectidae 

 Anguilliformes 



Engraulidae 

 Ostraciontidae 



Gadidae 



Atheriniformes 

 (Exocoetidae) 



Perciformes 

 Gadidae 



