Zoology Publications from Victoria University of Wellington—Nos. 78, 79 and 80
Terminology used in this guide essentially follows that of Gurney (1942). However, terminology used here to define developmental type and stage is given below.
Species with four or more planktonic zoeal instars in their life history.
|A.||Eyes sessile||zoea 1|
|B.||Uropods not freed from telson (Fig. 2F)||zoea 2|
|Uropods freed from telson||C|
|C.||Uropod endopod rudimentary (Fig. 2E)||zoea 3|
|Uropod endopod and exopod developed||D|
|D.||Pleopods absent or rudimentary (Fig. 2D)||zoea 4+|
|Pleopods setose and functional||postlarvae|
Early and late stages are arbitrarily defined. The terms are useful when referring to larvae in which the number of instars is variable or unknown, or when more than one instar is referred to. Early larvae are those in which there are no pleopod buds, and usually refers to zoeae 1-3. Late larvae are those in which all the appendages are present and well formed, and the pleopod buds are large but not yet setose. Intermediate classification into mid-stage larvae is only necessary when page 3there are a large number of instars and the degree of morphological change between them is small. Mid-stage larvae are zoea 4+ larvae in which pleopod buds are absent or small.
Larvae with development abbreviated to three or fewer instars follow the above pattern in development of the eyestalks and uropods. However, all other appendages including pleopod buds are present from zoea 1 onwards. For example, a zoea 3 larva with abbreviated development has rudimentary uropod endopods but also has large pleopod buds and is similar in other respects to late larvae with unabbreviated development.