FRITZSCHE: GASTEROSTEIFORMES 



403 



B 



Fig. 219. Larvae of some macrorhamphosoids and aulostomoids. (A) Macrorhamphosus scolopax. 9.0 mm TL (from Hardy, 1978a, after 

 D'Ancona, \97>'!i(X)\(Q) Aeoliscus stngalus. 7.9 mm (from Leisand Rennis, \9S3y, {C) Fisliilaria pelimba. 15.6 mm (from Leis and Rennis, 1983). 



terosteiforms. Kindred (1921) presented a classic study on the 

 chondrocranium of Syngnalhus fusciis. Padmanabhan (1961) 

 published information on the development of jaws in Solenos- 

 tomus cyanopterus. Development of the bony rings on the body 

 ofSyngnaihus typhle was studied in detail by Czolowska ( 1 962). 



Considering the diversity of habitats and spawning behaviors 

 found within the group, it is difficult to identify a character or 

 suite of characters that typifies all members of this order. Some 

 gasterosteiforms spawn in open water and produce buoyant eggs 

 (e.g., Fistularia. Watson and Leis, 1974); others such as the 

 sticklebacks and tubesnouts (Gasterosteidae and Aulorhynchi- 

 dae) construct nests out of vegetation for receipt of the eggs; 

 while others such as the seahorses, pipefishes, and ghost pipe- 

 fishes (Syngnathidae and Solenostomidae) brood the eggs within 

 specialized structures located on one of the parents. Syngnathids 

 have a most unusual adaptation in having a specialized patch 

 or pouch (marsupium) developed on the males for receipt and 

 incubation of eggs. Those groups containing species that broad- 

 cast spawn or have nests produce larvae that go through the 

 typical developmental pattern of pelagic larvae. Those that brood 

 eggs, such as the more advanced syngnathids, may retain the 

 eggs and developing larvae until the young have reached a ju- 

 venile stage of development. 



In general, eggs of most gasterosteiforms are spherical, how- 

 ever, those of Hippocampus have been described as being dis- 



tinctly pear-shaped (Hudson and Hardy. 1975) or ellipsoidal 

 (Nakamura, 1937) (Fig. 214). The eggs typically have numerous 

 oil droplets in the yolk (Gudger, 1905; Kuntz and Radcliffe, 

 1917). However, those of Fistularia lack oil droplets (Watson 

 and Leis, 1974), and Macrorhamphosus has a single oil globule 

 (Lo Bianco, 1909; Fage, 1918). The perivitelline space is narrow 

 in Solenostomus (Padmanabhan, 1961), gasterosteids (Hardy, 

 1978), and Fistularia (Mito, 1961a), while it is relatively wide 

 in Hippocampus (Hardy, 1 978a). The yolk is not segmented and 

 is typically yellow in syngnathids (James, 1970), rose- violet in 

 Macrorhamphosus (Hardy, 1 978a), and clear in Fistularia (Mito, 

 1961a). The chorion is typically smooth, however, small at- 

 tachment threads have been reported for some gasterosteids 

 (Hardy, 1978a). Most gasterosteiforms have eggs about 1.0mm 

 in diameter except that Solenostomus eggs are about 0.6 mm 

 (Padmanabhan, 1961) and Hippocampus eggs may approach 

 4.0 mm in one dimension (Hardy, 1978a). 



Larvae of most gasterosteiforms (except gasterosteids) have 

 a very distinctive, elongate snout bearing a small upturned mouth 

 which reflects a trenchant character of the adults (Figs. 2 1 5- 

 219). Meristic characters are quite variable in this order (Table 

 106). Myomere counts range from a low of 19 in pegasids to 87 

 in Fistularia (Leis and Rennis, 1983). Fin ray meristics are 

 equally variable and some groups lack one or all of the fins 

 (Table 106). Syngnathids, for example, may have to 60 dorsal 



