Larval development and behaviour of the mantis shrimp, Squilla armata Milne Edwards (Crustacea : Stomatopoda)

Journal of the Royal Society of New Zealand ISSN: 0303-6758 (Print) 1175-8899 (Online) Journal homepage: https://www.tandfonline.com/loi/tnzr20 Larval development and behaviour of the mantis shrimp, Squilla armata Milne Edwards (Crustacea : Stomatopoda) Rex R. Pyne To cite this article: Rex R. Pyne (1972) Larval development and behaviour of the mantis shrimp, Squillaarmata Milne Edwards (Crustacea : Stomatopoda), Journal of the Royal Society of New Zealand, 2:2, 121-146, DOI: 10.1080/03036758.1972.10429369 To link to this article: https://doi.org/10.1080/03036758.1972.10429369 Published online: 30 Jan 2012. Submit your article to this journal Article views: 897 Citing articles: 6 View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalinformation?journalcode=tnzr20

Journal of the Royal Society of New Zealand, 1972, Vol. 2, No.2, fip. 121-146, 16 figs Larval Development and Behaviour of the Mantis Shrimp, Squilla armata Milne Edwards (Crustacea: Stomatopoda) REX R. PYNE Victoria University of Wellington [Received by the Editor, 4 November 1970] Abstract Two propelagic and nine pelag-e larval stages of Squilla armata H. Milne Edwards, from New Zealand, are described and illustrated. A larval calendar showing monthly abundance and ratio of occurrence of pelagic larvae from the plankton in relation to the mean water temperature is given. Habits of the larvae are described. INTRODUCTION STOMATOPODS characteristically have a long larval life history. On hatching, the larvae spend two intermoults in a propelagic phase, followed by several intermoults in a pelagic phase, before metamorphosing into benthic juveniles. The translucent larvae exhibit many adult features, but the diagnostic adult characters do not appear until after metamorphosis. Observations on the Wellington Harbour plankton (Wear, 1965) have shown that stomatopod larvae form a large part of the temporary planktonic crustacean fauna. Despite their abundance in the plankton, the New Zealand larval stomatopods are virtually unknown, only Squilla armata Milne Edwards and Heterosquilla spinosa (Wood-Mason) having been positively identified. LARVAL IDENTIFICATION Earlier works on larval stomatopods have led to much confusion in recent years. Previous authors described stomatopod larvae as adult animals, assigning them separate generic and specific names. Further. these descriptions were generally based on a few specimens only, which led to different stages and individual variations being described as separate species, and different species as different stages of the same species. Claus (1871), after examining a large collection of larval Stomatopoda, concluded that there were two distinct forms of larval development, which he called " alima" and "erichthus". The basis of our present knowledge of the larval Stomatopoda is due to Giesbrecht (1910), who, in his study on the Mediterranean stomatopod larvae, followed the complete sequence of larval stages from hatching to metamorphosis for the first time, giving a full description of changes in external body form. Giesbrecht also recognised, in the early stages of development, two types of larvae, which he termed cc pseudozoea " and" antizoea ". During recent years, several authors (Foxon, 1932, 1939; Gurney, 1937, 1946; Townsley, 1953) tried to interpret the various types of stomatopod larvae in terms of adult and larval classifications. However, Manning and Provenzano (1963) have pointed out that this approach is unsatisfactory because "the entire order is in need of revision at the generic level and, until this has been accomplished, attempts to fit larval stomatopods into the classification of adults is premature".

122 JOURNAL OF THE ROYAL SOCIETY OF NEW ZEALAND TABLE I.-Larval species of Stomatopoda that have been identified by hatching from the egg or from rearing late-stage larvae through metamorphosis to the juvenile stage LARVAL IDENTIFICATION BY HATCHING EGGS Squilla armata Squilla mantis Squilla oratoria Gonodactylus chiragra Gonodactylus [alcatus Gonodactylus lenzi Gonodactylus oerstedii Pseudosquilla ciliata Garrick and Yaldwyn, 1952 (pers. comm.) Mayer, 1877; Giesbrecht, 1910 Komai, 1924 Serene, 1954 Gurney, 1937; Serene, 1954; Gohar and Al-Kholy, 1957 Serene, 1954 Brooks, 1891; Gurney, 1946; Manning, 1963 Clark, (1869?) LARVAL IDENTIFICATION JUVENILE STAGE Squilla armata Squilla boops Squilla desmaresti Squilla empusa Squilla fascata Squilla gonypetes Squilla hieroglyphics Squilla holoschista Squilla interrupta Squilla lata Squilla latreillei Squilla nepa Squilla quadridens Squilla quinquedentata BY REARING LATE-STAGE LARVAE THROUGH METAMORPHOSIS TO THE Wear, 1965 Giesbrecht, 1910 Faxon, 1892 Bigelow, 1894 H eterosquilla Squilla raphidea Squilla tricarinata Squilla wood-masoni Lysiosquilla acanthocarpus Lysiosquilla eusebia Lysiosquilla excavatrix Lysiosquilla maculata Lysiosquilla multifasciata Lysiosquilla sulcirostris Lysiosquilla tigrina spinosa Wear, 1965. Gurney, 1946 Giesbrecht, 1910 Brooks, 1886 Thus, the problem of relating the numerous larval forms to their corresponding adult remains practically unsolved, only 32 different stomatopod larvae having been positively identified to species. Of these, seven have been identified by hatching the egg, and 25 by rearing late pelagic stages to metamorphosis (Table 1). This latter method was suggested by Brooks (1886), Lebour (1934), and Foxon (1939) as a means of positive identification, though Gurney (1946) believed the only reliable means of identification was to hatch larvae from eggs. In view of the difficulty in obtaining adults with eggs, Gurney regarded the rearing of late-stage planktonic larvae through to metamorphosis to be an important contribution towards larval identification. Because of the long larval life history, it has not been possible to follow the larval sequence entirely by rearing the first pelagic larvae through to metamorphosis. Therefore, in order to complete the broken series, several authors (Brooks, 1879; Giesbrecht, 1910; Gohar and Al-Kholy, 1957) found it necessary to resort to planktonic collections, employing two different methods for identification: a. tracing the larval sequence from preserved material, relying on progressive anatomical developmental characters; b. holding planktonic larvae in the laboratory through one ecdysis to associate two successive stages. The methods used for larval identification in the present study were: a. eggs from adult Squilla armata captured in Wellington Harbour, were hatched in the laboratory and the larvae held through two ecdyses, enabling positive identification of the first and second propelagic and first pelagic stage larvae; b. the second to seventh pelagic larval stages were identified from the plankton samples collected from Wellington Harbour, relying on progressive anatomical developmental characters;

PYNE-Larval Characters of Squilla armata 123 c. holding pelagic larvae, identified by method b, through one ecdysis in order to associate two successive stages; d. holding late stage pelagic larvae from. the plankton through to metamorphosis in the laboratory where they could be positively identified with the adult. MATERIAL AND METHODS Plankton samples were collected from various stations in Wellington Harbour (Fig. 1) between 1 March 1964 and 28 February 1965. Kau Bay was selected as the main plankton station, samples being collected twice monthly, using a standard one-metre cone net of 32 gauge mesh, towed for 10 minutes. Plankton samples were transported live to the shore laboratory for examination. LOC ATION MAP Regular ~ ampl in g stot lo n, + Addit ional ~ am pl in g stcrtcns. WELLINGTON Harbour Ent r ance................ ',.,..........,....,. +,.......,100 d-...... "'. "... ~ s o m " ~ I ~....... +................................... HARBOUR............. + +... I : :................ ; ~ Ward I ~... +..... [7.............................................. '............................... ~. :.:.:. :.:.:.:.:.:.:.:.: """.. -:.:.:-:.:.:.:. :.:-:. :-:.: -: 1 0 1... _:::oj...t: ' M i le ~...... FIG. I.-Map of Wellington Harbour, showing the Wellington Harbour plankton sampling stations.

124 JOURNAL OF THE ROYAL SoCIETY OF NEW ZEALAND Adult S. armata were captured alive from Wellington Harbour using either a small otter-trawl net or a beach-seine. The total number of S. armata larvae in each plankton sample was counted. All undamaged actively swimming larvae were removed for rearing experiments, the remaining larvae being preserved in 70 percent isopropyl alcohol. Active larvae retained for experiments were placed in 4in. diameter finger bowls containing fresh-filtered sea water and maintained at a constant water temperature of 13.5 C in total darkness. Sea water was changed daily, dead larvae and exuviae being removed and preserved. Eggs laid by adult S. armata kept in the laboratory aquaria were either: a. incubated by the female; b. incubated artificially in "hatcheries" supplied with filtered running sea water (Fig. 2C). About one week before the eggs were due to hatch by either of the above methods, the eggs were removed and placed in compartment trays (Fig. 2A, B) supplied with filtered running sea water. On hatching, the larvae were removed from the compartment trays and placed in separate containers for rearing. Five different methods were used in attempts to rear the propelagic larvae, hatched from S. armata eggs, through to metamorphosis. Using filtered sea water, the first propelagic larvae were distributed and held as follows: a. separately in 50 ml glass jars; b. in groups of 10 in 4in diameter finger bowls; c. in groups of 50-100 in 7in diameter finger bowls; orrr,==;=,=,r===;,r===;,r===;,r===l1-'1 Automatic 5i phon P.rforation!> o 1 II t»: FIG. 2.-A. Plan view of larval rearing container. B. Side vicw of above, showing direction of water flow and position of automatic siphon. O. Egg hatching container, direction of water flow indicated.

PYNE-Larval Characters of Squilla armata 125 d. in groups of up to 20 in 2in square compartment trays; e. more than 100 in glass containers. Larvae reared under methods a, b, and c were kept at a constant water temperature of 13.5 C in total darkness, the water being changed daily, and larvae reared under methods d and e were subjected to diffused light in filtered running sea water. Larvae were checked daily, all exuviae and dead larvae being removed and preserved. No attempt was made to feed the two propelagic larval stages. Several attempts were made to feed the pelagic larval stages using the following food material: a. fertilised eggs and larvae of the tube-worm Polystoma spp.; b. Artemia larvae; c. decapod zoeae and cope pods taken alive from plankton collections; d. pieces of gonad and mantle of Perna canaliculus; e. powdered egg yolk. RESULTS Two S. armata egg masses were laid and hatched in the laboratory. The first egg mass, laid on 21 August 1965, was incubated by the female and hatched on 31 October 1965, an incubation period of 72 days. The second egg mass was laid on 22 August 1965 and incubated artificially, hatched on 3 November 1965, an incubation period of 74 days. TABLE 2.~Number of surviving larvae each day after hatching eggs obtained from one egg mass Date October 31 November I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 December I 2 First propelagic 2 s 12.'12 76 69 60 21 6 Second propelagic 6 13 22 61 75 77 74 62 45 8 First pelagic 1 5 7 18 35 70 77 77 76 74 69 68 66 64 60 59 38 30 269 6 6 2

126 JOURNAL OF THE ROYAL SoCIETY OF NEW ZEALAND Larvae obtained from laboratory hatchings were held through to the first pelagic stage with no difficulty, and mortality in the first and second propelagic stages was negligible (Table 2), as the larvae probably subsisted on yolk material retained from the egg. The duration of the propelagic phase of the life history being between 9-12 days. By the time the second propelagic stage larvae ecdysed into the first pelagic stage, all the yolk had disappeared, the mandibles appeared and other mouth-parts were now apparently functional. Despite repeated attempts using a variety of foods, the first pelagic stage larvae could not be induced to feed, this resulting in eventual death. Gurney (1937) and Manning and Provenzano (1963) reported similar findings when rearing the larvae of Gonodactylus oerstedii Hansen. ROSTRUM - OCULAR SOMITE Rostrum Length. AN TERO-LATERAL SPINE Car apace Length. Tot al Le ngth ABDOMINAL SOMI TES Abdome n Length. l oteral Interm ediate spine- $opine- Sub- median spine Su b..me dian de ntler,,5o FIG. 3.-Diagrammatic sketch of S. armata larva, illustrating terms used in the description and the method of measurement.

PYNE-Larval Characters of Squilla armata 127 In order to complete the pelagic larval series, the author was obliged to refer to live larval material from plankton collections. Four hundred and sixteen pelagic larvae of various stages were successfully reared in the laboratory through at least one ecdysis, the first to seventh pelagic stage larvae living for short periods only (10-16 days). It was possible, however, to keep later stage pelagic larvae for very much longer periods (up to 165 days) during which time they passed through as many as six ecdyses. As a result of repeated failures, the most suitable condition for holding live larvae in the laboratory was found to be at a water temperature of 13.5 C in total darkness. Live food material was found more satisfactory for experimental purposes as "dead" food material rapidly contaminated the water. B c E~ D~ G F H J A-B 0 5mm. c 0- -0:5 mm.--. D-K 0 5 mm. FIG. 4.-First propelagic larval stage. A. First propelagic larva, lateral view. B. First propelagic larva, dorsal view. C. Second maxilliped on right side, lateral view. D. Antennule on right side, dorsal view. E. Antenna on right side, dorsal view. F. First maxilliped on right side, lateral view. G. Telson, dorsal view. H. First abdominal pleopod on right side, ventral view. L Second abdominal pleopod on right side, ventral view. J. Third abdominal pleopod on right side, ventral view. K. Fourth abdominal pleopod on right side, ventral view.

128 JOURNAL OF THE ROYAL SoCIETY OF NEW ZEALAND Illustrations and measurements were made from preserved material and checked against living or freshly killed specimens. All illustrations were made with the aid of a camera lucida. Anatomical terms and methods of measurements used in the text have been illustrated in Fig. 3. DESCRIPTIONS OF THE Two PROPELAGIC AND NINE PELAGrC LARVAL STAGES OF S. armata FIRST PROPELAGlC LARVAL STAGE (FIG. 4) Total length: 2.3-3.2 mm. Larval duration: 4-6 days. Larvae are translucent; cuticle soft and wrinkled. Large yolk reserve retained from the egg is stored in the thoracic region which is vaulted dorsally; abdomen curved strongly ventrad. Carapace (Fig. 4A, B) length 0.9-0.95 mm; shield-like in shape and armed with several spines; a short spine at each anterolateral corner (anterolateral spine), a long spine at each posterolateral corner (posterolateral spine), a median spine on the posterior border (median posterior spine). The median anterior margin of the carapace is produced into a smooth rostrum (length 0.2-0.3 mm) not extending beyond the antennular peduncles, broad and curved slightly ventrad. Ocular and antennary sornites partially fused. Eyes large, ovoid; length of cornea twice length of eye peduncle. Antennule (Fig. 4D) with three stout basal segments, the apical segment giving rise to two filamentous distal branches, the flageilae; inner flagellum twosegmented, apical segment with long apical seta; un i-segmented outer flagellum with one apical seta on the inner margin. Antennae (Fig. 4E) uniramous; distal segment scale-like, armed with five (occasionally four) marginal plumose setae. Mandibles and maxillae absent. The first three to four thoracic somites overlapped by the carapace; exposed thoracic somites of equal length and width; no trace of appendages on the third to eighth somites. First and second pairs of maxillipeds well developed, each with six segments (Fig. 4H, I); dactylus not reflected on second maxilliped; inner margin of propodus and dactylus smooth. Boundary between thorax and abdomen mid-way between base of rostrum and posterior margin of telson. Abdomen (Fig. 4A, B) length 1.4-1.6 mm; broader than thorax; curved strongly ventrad. Five abdominal somites distinguishable, the sixth fused with teison. Paired biramous pleopods present on first to fourth abdominal somites (Fig. 4H-K); endopod with appendix interna present on inner margin; pleopod setation detailed in Table 3. Lateral margin of telson (Fig. 4G) convex, armed with paired lateral, intermediate and submedian fixed spines; 5-7 small intermediate denticles. Posterior margin of telson broadly concave between paired submedian spines; 19-2 I small submedian denticles. SECOND PROPELAGIC LARVAL STAGE (FIG. 5) Total length: 2.75-3.65 mm. Larval duration: 5-6 days. Thoracic region only slightly vaulted, the yolk reserve being greatly reduced. Body cuticle smooth and hard, the larvae now having a definite body outline. Carapace (Fig. 5A, B) length 1.6-2.0 mm; length twice greatest carapace width. Posterolateral spines extending to middle of first abdominal somite. Rostrum length 0.6-0.7 mm; narrow; extending beyond the antennular peduncles. Ocular and antennary somites with evidence of segmentation. Eyes piriform; length of eye sub equal to peduncle. Inner and outer antennular flagellae with increased number of proximal setae (Fig. 5F). Antennal scale (Fig. 5D) with 7-9 marginal plumose setae. Paired mandibular, maxillular and maxilla buds present posterior to the labrum. Exposed thoracic somites narrowed slightly. Dactylus of first maxilliped partially reflected upon propod; distal margin of propod with up to nine strong setae; carpus with one strong distal seta. All six segments of second maxilliped (Fig. 5C) longer and narrower than preceding stage; dactyle reflected upon propod, giving appearance of a typical adult raptorial limb; a short scale-like epipodite present on the basal segment. Abdomen (Fig. 5A, B) length 1.6-1.8 mm. Telson (Fig. 5E) length greater than preceding stage; 6-8 intermediate and 19-2 I submedian denticles. FIRST PELAGIC LARVAL STAGE (FIG. 6) Total length: 4.2-5.6 mm. Larval duration: greater than nineteen days. This is the first larval stage after hatching from the egg to appear in the plankton collections. No yolk material is present. Carapace (Fig. 6A, B) length 1.15-1.4 mm; width three-quarters length. Lateral margins of carapace curved slightly ventrad and armed with 1-10 spinules on the posterolateral margin; posterolateral spines armed with 6-16 spirally arranged spinules; median posterior spine armed with 5-10 spirally arranged spinules. Rostrum (Fig. 6A, B) length 1.1-1.4 mm;

PYNE-Larvcl Characters 0/ Squilla armata 129 armed with 5-6 large anteroventral spinules and 10-26 smaller spirally arranged spinules (spinules on rostrum and carapace are not illustrated). Ocular somite clearly demarcated from antennary somite. Ocular somite with one small spine on median ventral margin. Antennary somite with one small median ventral spine between the base of the antennules and antennae. Third basal segment of antennule with one long seta on inner margin (Fig. 6G). Antennal apical scale with 10-12 marginal plumose setae (Fig. 6D). Paired mandibles (Fig. 6J) with serrate distal margins; maxiiiula and maxilla functional. B (p~ c E F A-O c >--- - --< O Smm. 0-5mm. O-K O-S mm. FIG. 5.-Second propelagic larval stage. A. Second propelagic larval stage, lateral view. B. Second propelagic larval stage, dorsal view. C. Second maxilliped on nght side, lateral view. D. Antenna on right side, dorsal view. E. TeIson, dorsal view. F. Antennule on right side, dorsal view. G. First maxilliped on right side, lateral view. H. First abdominal pleopod on right side, ventral view. 1. Second abdominal pleopod on right side, ventral view. J. Third abdominal pleopod on right side, ventral view. K. Fourth abdominal pleopod on right side, ventral view.

130 JOURNAL OF THE ROYAL SoCIETY OF NEW ZEALAND Dactylus of first maxilliped (Fig. 6H, I) small, pointed and reflected against the propod; propod with 12 distal setae and two small spines adjacent to the dactyl; carpus with two strong distal setae. Dactyl of second maxilliped (Fig. 6C) falciform, with inner distal margin finely serrate; inner margin of propod with 1-2 large proximal articulated spines and I G-16 smaller fixed spines or denticles. Abdomen (Fig. 6A, B) length 1.8-2.9 mm; curved only slightly ventrad. Future segmentational division between the sixth abdominal somite and tel son indicated dorsally by a pair of small submedian spines. B G n rn F! C.OE. G.H. A.B. iu.m.n. o 5mm. 0 '5""". O'5mm 0 5O'm. O 5mm. 1 mm. Imm. FIG. 6.-First pelagic larval stage. A. First pelagic larva, lateral view. B. First pelagic larva, dorsal view. C. Second maxilliped on right side, lateral view. D. Antenna on right side, dorsal view. E. Telson, dorsal view. F. Submedian denticles on telson illustrating arrangement of spinules, dorsal VIeW. G. Antennule on right side, dorsal view. H. First maxilliped on right side, lateral view. 1. Dactylus and propod of first maxilliped. J. Mandible. K. First abdominal pleopod on right side, ventral view. L. Second abdominal pleopod on right side, ventral view. M. Third abdominal pleopod on right side, ventral view. N. Fourth abdominal pleopod on right sige, ventral view.

PYNE-Larval Characters of Squilla armata 131 Telson (Fig. 6E) with 5-8 intermediate and 20-24 submedian denticles. The submedian denticles have become further subdivided into very minute denticles arranged 6-5-9 (Fig. 6F). SECOND PELAGIC LARVAL STAGE (FIG. 7) Total length: 6.2~7.3 mm. Carapace (Fig. 7A, B) length 1.5-1.95 mm; posterior margin reaching to the seventh thoracic somite; width two-thirds length. Posterolateral spines reaching to fourth abdominal somite, each with three large ventral spines. Lateral margin of carapace with 2-3 anterior Hfj o G.I\N. D.r. A. O 5mm. 05mm. D 5mm. 12 - Imm. B.C. Imm. E.J.IU... O.5 mm FIG. 7.-Second pelagic larval stage. A. Second pelagic larva, lateral view. B. Second pelagic larva, dorsal view. C. Second maxilliped on right side, lateral view. D. Antenna on right side, dorsal view. E. TeIson, dorsal view. F. Antennule on right side, dorsal view. G. Dactylus, propod and carpus of first maxilliped, lateral view. H. Mandible. I. Division of the right intermediate fixed spine of telson, dorsal view. J. First abdominal pleopod on right side, ventral view. K. Second abdominal pleopod on right side, ventral view. L. Third abdominal pleopod on right side, ventral view. :M. Fourth abdominal pleopod on right side, ventral view. N. Fifth abdominal pleopod on right side, ventral view.

132 JOURNAL OF THE ROYAL SOCIETY OF NEW ZEALAND and 1-4- posterior spinules. The small spirally arranged spinules present in the preceding stage are absent on the median and posterolateral spines. Rostrum (Fig. 7A, B) length 1.8-2.5 mm; rostrum length greater than carapace length; five large spines on anteroventrai margin; spinules absent. Inner flagellum of antennule (Fig. 7F) same as preceding stage; outer flagellum divided (partial division in some specimens) into, (a) a narrow, two-segmented median flagellum, the apical segment with one long seta, and (b) a broader outer flagellum with eight proximal setae arranged 2-2-2-2 along inner margin. Antennal apical scale (Fig. 7D) with 11-23 marginal plumose setae; endopod bud present. o C.O o ~mn. [.K!.II. 0 5 '0 '0 A hnm.: G ''Om BUH ". I"" ", M FIG. 8.-Third pelagic larval stage. A. Third pelagic larva, dorsal view. B. Telson, dorsal view. C. Intermediate denticles of the tel son illustrating minute spination on the inner margins, dorsal view. D. Submedian spines of telson illustrating articulating tip, dorsal view. E. Antenna on right side, dorsal view. F. Antennule on right side, dorsal view. G. Second maxilliped on right side, lateral view. H. Dactylus, propod, carpus of first maxilliped on right side, lateral view. I. Mandible. J. First abdominal pleopod on right side, ventral view. K. Second abdominal pleopod on right side, ventral view. L. Third abdominal pleopod on right side, ventral view. M. Fourth abdominal pleopod on right side, ventral view. N. Fifth abdominal pleopod on right side, ventral view.

PYNE~Larval Characters of Squilla armata 133 First maxilliped (Fig. 7G) same as preceding stage. Propod of second maxilliped (Fig. 7C) with two large proximal articulated spines and 15-20 smaller fixed denticles on the inner margin. Third pair of maxillipeds present as buds. Abdomen (Fig. 7A, B) length 2.5-3.3 mm. Fifth pair of pleopods present as biramous, non-setose buds (Fig. 7N); appendix interna extending two-thirds length of endopod. Tclson (Fig. 7L) length slightly greater than width; 6-8 intermediate and 23-26 submedian denticles. The lateral and intermediate fixed spines are in the process of dividing (Fig. 7E). THIRD PELAGIC LARVAL STAGE (FIG. 8) Total length: 7.8-8.0 mm. Carapace (Fig. 8A) length 1.9-2.8 mm; lateral margin with 2-3 anterior and two posterior spinules. Rostrum length 2.1-3.0 mm. Increased number of proximal setae on outer flagellum of antennule (Fig. SF); length of median flagellum increased. Antennal apical scale (Fig. 8E) with 12-16 marginal plumose setae; length of unsegmented endopod increased. Propod of first maxilliped (Fig. 8K) with 14 distal setae; carpus with four inner distal setae. Propod of second maxilliped (Fig. 8G) with three large proximal articulated spines and 17-24 smaller fixed denticles. Unsegmented, biramous third maxilliped buds increased in length. Fourth and fifth maxillipeds present as paired buds. Abdomen (Fig. 8A) length 2.9-3.5 mrn. Sixth abdominal somite clearly demarcated from the telson on the ventral surface. Gill buds present as small rounded lobes on the inner proximal margin of the exopod en the first four pairs of pleopods. Fifth pair of pleopods setose; appendix interna extends half the length of the endopod. Paired biramous, nonsetose uropod buds present on the sixth abdominal somite (Fig. 8B); basipodial process absent. Telson (Fig. 8B) length and width sub equal ; 7-9 intermediate and 39-42 submedian denticles. A small fixed spine is present in the axis of the paired lateral and intermediate fixed spines (result of division commenced in preceding stage). FOURTH PELAGIC LARVAL STAGE (FIG 9) Total length: 8.8-9.9 mm. Carapace (Fig. 9A) length 2.25-2.65 mm; 2-3 anterior and one posterior spinule on lateral carapace margin. Rostrum length 2.4--3.1 mm. Broad, unsegmented outer flagellum of antennule (Fig. 9E) with setae arranged 1-2-2-2-2 on inner proximal margin; inner flagellum three-segmented. Antennal exopod scale (Fig. 9B) with 11-23 marginal plumose setae; endopod reaching base of exopod scale, is partially or completely divided into two segments. Fifth maxiiiiped (Fig. 9L) with many setae on inner margin of both propod and carpus. Dactyl of second maxilliped with one "tooth" (other than terminal one) visible or just exposed beneath the integument on the inner proximal margin; inner margin of propod with 20---25 small fixed denticles. Third maxilliped four-segmented. Fourth and fifth maxillipeds three-segmented. Paired pereiopods present as biramous buds on the sixth to eighth thoracic somites (Fig. 9H). Abdomen (Fig. 9A) length 3.4--4.5 mm; rudimentary gills bi-iobed on first to fourth paired pleopods. Basipodial process present on uropod buds. Telson (Fig. 9C) with 10---14 intermediate and 41-42 submedian denticles. FIFTH PELAGIC LARVAL STAGE (FIG. 10) Total length: 10.5-11.8 mm. Carapace (Fig. loa) length 2.8-3.2 mm : one anterior and one posterior spinule on lateral carapace margin. Rostrum length 2.7-3.3 mm; 4-6 large ventrodistal spinules. Outer flagellum of antennule (Fig. 10E) with setae arranged 1-2-2-2-2-2 on inner proximal margin; both median and inner flagei!um four-segmented. Antennal exopod scale (Fig. lob) with 21-26 marginal plumose setae; endopod three-segmented. Propod of first maxilliped (Fig. IOJ) with 17-2 I setae on proximal margin; carpus with seven setae on inner distal margin. Dactyl of second maxilliped (Fig. ION) with two "teeth" (including terminal" tooth "); propod with 22-26 small fixed denticles. Third to fifth maxillipeds five-segmented (Fig. IOK-M): dactyl of third and fourth maxillipeds reflected against the propod. Biramous pereiopods increased in length (Fig. 1OG-I). Abdomen (Fig. loa) length 4.6--5.6 mm. Gill buds present on fifth pair of pleopods. Exopod of uropod (Fig. IOD) with five distal marginal plumose setae, and one articulated spine midway along outer proximal margin; endopod with three distal marginal plumose setae; basipodial process with one long inner and one short outer spine. Telson (Fig. IOC) with 12-14 intermediate and 37-38 submedian denticles. SIXTH PELAGIC LARVAL STAGE (FIG. 11) Total length: 12.7-13.0 mm. Carapace (Fig. l1a) length 3.2-3.6 mm. Rostrum length 3.0-3.7 mm.

134 JOURNAL OF THE ROYAL SoCIETY OF NEW ZEALAND Outer flagellum of antennule (Fig. llf) with setae arranged 2-2-,-2-2-2-2 on inner margin; median flagellum 4-5 segmented; inner flagellum length greater than rostrum length. Antennal exopod scale (Fig. lib) with 30--34 marginal plumose setae; apical exopod segment increased in length, with annulations along its distal margin. Propod of first maxilliped (Fig. 110) with 20--24 proximal setae and three small" teeth" on inner distal margin; carpus with 10 setae on inner distal margin. Dactyl of second A D~ G Il H I~ Jg D.D.L.N. O 5mm. K d L I,!I\. --- O Srnm. H. O 5 mm. A f. 1... - - - I mm. - - - - B CE.,.. Imm. FIG. 9.-Fourth pelagic larval stage. A. Fourth pelagic larva, dorsal view. B. Antenna on right side, dorsal view. C. Telson, dorsal view. D. Uropod on right side, dorsal view. E. Antennule on right side, dorsal view. F. Second maxilliped on right side, lateral view. G. Mandible. H. Ventral view of the sixth, seventh and eighth thoracic somites showing the buds of the first to third paired pereiopods. I. Third maxilliped on right side, dorsal view. J. Fourth maxilliped on right side, dorsal view. K. Fifth maxilliped on right side, dorsal view. L. Dactylus, propod and carpus of first maxilliped on right side, lateral view. M. First abdominal pleopod on right side, ventral view. N. Fifth abdominal pleopod on right side, ventral view.

PYNE-Larval Characters of Squilla arma ta 135 maxilliped (Fig. IIG ) with three "teeth " on inn er ma rgin ; prop od with 24-38 small fixed denticles. Third maxilliped (Fig. 11K ) with one small spine on upper distal margin of carpus. Dactyl of fifth maxilliped only partially reflected (Fig. I IM ). Exopod of first and second pereiopods two-segmented (Fig. llh, I); exopod of thi rd pereiopod unsegmented. Endopod of all three pairs of pereiop ods shorter than exopods. FI1 G ~ HD- l.rq J F. O!tmm. O.G.H.I,K.l./04F! D,Srom. O"Smm. A. C.H. O. E.O. lmm. lm m. Im m, FIG. IO.-Fifth pelagic lar val stage. A. Fifth pelagic larva, dorsal view. B. Antenna on right side, dorsal view. C. T elson, dorsal view. D. Uropod on left side, dorsal view. E. Antennule on right side, dorsal view. F. Mandible. G. First pereiopod on right side, lateral view. H. Second pereiop od on right side, lat eral view. I. Third pereiop od on right side, lateral view. J. Dactylus, propod and carpus of first maxilliped, lat eral view. K. Third maxillip ed on right side, lateral view. L. Fourth maxilliped on right side, lat eral view. M. Fifth ma xilli ped on right side, lateral view. N. Second ma xillipe d on right side, lat eral view. O. First abdominal pieopod on right side, ventral view. P. Fifth abdominal ple opod on right side, ventral view.

136 JOURNAL OF THE ROYAL SoCIETY OF NEW ZEALAND D~ M NYf o E.H.I J. Kl...N a-s Mm. Q O.P.O. O 5 mm.. A. c.r,o. B.D. 1m... 1mm. 1mm. FIG. ll.-sixth pelagic larval stage. A. Sixth pelagic larva, dorsal view. B. Antenna on right side, dorsal view. C. TeIson, dorsal view. D. Denticulation between the submedian spines of telson. E. Uropod on right side, dorsal view. F. Antennule on right side, dorsal view. G. Second maxiiiiped on right side, lateral view. H. First pereiopod on right side, lateral view. I. Second pereiopod on right side, lateral view. J. Third pereiopod on right side, lateral view. K. Third maxiiiiped on right side, lateral view. L. Fourth maxiiiiped on right side, lateral view. M. Fifth maxiiiiped on right side, lateral view. N. Mandible. O. Dactylus, propod, carpus and merus of first maxiiiiped on right side, lateral view. P. First abdominal pleopod on right side, ventral view. Q. Fifth abdominal pleopod on right side, ventral view.

PYNE-Larval Characters of Squilla armata 137 A If L M p O 5mm. O 5 rtyn. I mm. Imm. O,E.F.O.P. I mm. f{ Imm. FIG. 12.-Seventh pelagic larval stage. A. Seventh pelagic larva, dorsal view. B. Antenna on right side, dorsal view. C. Telson, dorsal view. D. Detail of hind margin of telson illustrating intermediate and submedian denticulation, dorsal view. E. Uropod on right side, dorsal view. F. Antennule on right side, dorsal view. G. Third maxilliped on right side, lateral view. H. Fourth maxilliped on right side, lateral view. I. Fifth maxilliped on right side, lateral view. J. Second maxilliped on right side, lateral view. K. First pereiopod on right side, lateral view. L. Second pereiopod on right side, lateral view. M. Third pereiopod on right side, lateral view. N. Dactylus, propod and carpus of first maxilliped, lateral view. O. First abdominal pleopod on right side, ventral view. P. Fifth abdominal pleopod on right side, ventral view.

138 JOURNAL OF THE ROYAL SOCIETY OF NEW ZEALAND Abdomen (Fig. 11A) length 5.8-7.3 mm. Sixth abdominal somite completely demarcated from tel son on both surfaces. Exopod of uropod (Fig. lie) separated into a basal and apical segment; basal segment with 2-3 large graded articulated spines on outer distal margin; apical segment with 13-16 distal marginal plumose setae. Endopod of uropod with 8-11 distal marginal plumose setae. Telson (Fig. 11C) width greater than length; 14--15 intermediate and 40-55 submedian denticles. SEVENTH PELAGIC LARVAL STAGE (FIG. 12) Total length: 13.5-16.2 mm. Carapace (Fig. 12A) length 3.6--4.2 mm. Carapace longer than rostrum. Rostrum length 3.3-3.9 mm; four small venterodistal spinules. Outer flagellum of antennule (Fig. 12F) with setae arranged 2-2-2-2-2-2-1 on inner margin; median flagellum 6--7 segmented; inner flagellum 11-13 segmented. Antennal exopod scale with 35-46 distal marginal plumose setae; endopod with three large basal segments and 3-4 smaller apical flagella segments. Dactyl of first maxilliped (Fig. 12N) with one small proximal seta on outer margin; propod with 20-25 setae on inner proximal margin; carpus with 15 setae on outer proximal margin. Dactyl of second maxilliped (Fig. 12]) with 3-4 "teeth"; propod with 24--26 small fixed denticles. Propod of fourth and fifth with three small proximal spines. Dactyl of fifth maxilliped reflected against propod. Exopod of first to third pereiopods two-segmented (Fig. 12K-M); unsegmented endopod shorter and narrower than exopod. First to third pereipods same as preceding stage. Abdomen (Fig. 12A) length 6.2-8.5 mm; gills tri-iobed, the distal branch being twobranched (Fig. 120, Pl. Endopod of uropod (Fig. 12E) slightly shorter than exopod; 14--20 marginal plumose setae. Basal exopod segment of uropod with 4--6 graded distal articulated spines on outer margin; apical segment with 16-18 distal marginal plumose setae. Long inner spine of basipodial process with a blunt spine on outer proximal margin. Telson (Fig. 12C, D) with 14--19 intermediate and 45-55 submedian denticles. EIGHTH PELAGIC LARVAL STAGE (FIG. 13) Total length: 17.2-17.5 mm. Larval duration: 30-31 days. Carapace (Fig. 13A) length 4.2-4.65 mm, Rostrum length 4.0-4.2 mm; 3-5 small venterodistal spinules. Outer flagellum of antennule (Fig. 13F) with setae arranged 2-2-2-2-2-2-2-1 on inner proximal margin; median flagellum 8-9 segmented; inner flagellum 12-18 segmented. Antennal exopod scale (Fig. 13B) with 45-55 marginal plumose setae; endopod flagellum 6--7 segmented, reaching nearly to tip of exopod scale. Dactyl of first maxilliped (Fig. 13N) with three" teeth" on inner margin plus three small setae on outer proximal margin; propod with three small distal spines adjacent to dactyl, 20-25 proximal setae on inner margin and three small setae on outer distal margin. Dactyl of second maxilliped (Fig. 13G) with 3-6 " teeth"; propod with 40-50 small fixed denticles on inner margin. Propod of fourth and fifth maxillipeds (Fig. 131, J) with four small proximal spines on inner margin. First to third pereiopods same as preceding stage. Abdomen (Fig. 13A) length 8.7-9.2 mm; distal gill lobe pinnate (Fig. 130, Pl. Basal exopod segment of uropod (Fig. 13E) with 4--6 graded, distal, articulated spines; apical exopod segment with 20-25 distal marginal plumose setae; endopod with 20-26 distal marginal plumose setae. Telson (Fig. 13C, D) with 14--17 intermediate and 40-50 submedian denticles. NINTH PELAGIC LARVAL STAGE (FIG. 14) Total length: 20.0-21.5 mm. Larval duration: 30-31 days. Carapace (Fig. HA) length 4.7-5.25 mm. Rostrum length 3.8-4.5 mm; smooth, with spines absent from ventral surface. Ventral spines on antennary somite absent. Outer flagellum of antennule (Fig. 14F) with setae arranged 2-2-2-2-2-2-2-2-2-2-2 on inner proximal margin; median flagellum 15-20 segmented; inner flagellum 18-24 segmented. Antennal exopod scale (Fig. 14B) with 50-60 distal marginal plumose setae; endopod flagella nine segmented. Dactyl of first maxilliped (Fig. 14Q) with four "teeth" on inner proximal margin; propod with three small spines adjacent to dactyl and 35-45 proximal setae on inner margin. Dactyl of second maxilliped (Fig. 14G) with 5-8 teeth; propod with 4-0-50 small fixed denticles. Propod of third to fifth maxillipeds (Fig. 14H-J) with 6--10 small proximal spines on inner margin; carpus with three spines on upper distal margin. First to third pereiopods (Fig. HK-M) same as preceding stage. Abdomen (Fig. HA) length 11.1-12 mm; distal gill lobe bi-pinnate (Fig. 140, P). Basal exopod segment of uropod with seven graded distal spines on outer margin (Fig. 14E): apical exopod segment with 40-45 distal marginal plumose setae; endopod with 35-45 distal marginal plumose setae; inner spine of basipodial process with a single blunt spine on outer proximal margin. A small dorsal spine present on distal margin of basal uropod segment. TeIson (Fig. 14C, D) with 14--18 intermediate and 40-50 submedian denticles.

PYNE-Larval Characters of Squilla armata 139 A K L M ' m",. - C.E.G,H.I.J ~ B.o.r,K.l.M,N.O.P. 'm"" FIG. 13.-Eighth pelagic larval stage. A. Eighth pelagic larva, dorsal view. B. Antenna on right side, dorsal view. C. Telson, dorsal view. D. Hind margin of telson illustrating denticulation between intermediate and submedian fixed spines, dorsal view. E. Uropod on right side, dorsal view. F. Antennule on right side, dorsal view. G. Second maxilliped on right side, lateral view. H. Third maxilliped on right side, lateral view. I. Fourth maxiiiiped on right side, lateral view. J. Fifth maxilliped on right side, lateral view. K. First pereiopod on right side, lateral view. L. Second pereiopod on right side, lateral view. M. Third pereiopod on right side, lateral view. N. Dactylus, propod, carpus and merus of first maxiiiiped on right side, lateral view. O. First abdominal pleopod on right side, ventral view. P. Fifth abdominal pleopod on right side, ventral view.

140 JOURNAL OF THE ROYAL SoCIbTY OF NEW ZEALAND M "": o < ~:r~ P Q. H. A. c. O 5 mm. O 5mm. l mm. lm m. B.F.G.H.UQP lmm. D.E./I.!..Iot l mm. FIG. H.-Ninth pelagic larval stage. A. Ninth pelagic larva, dorsal view. B. Antenna on right side, dorsal view. C. Telson, dorsal view. D. Hind margin of telson illustrating intermediate and submedian denticulation, dorsal view. E. Uropod on right side, dorsal view. F. Antennule on right side, dorsal view. G. Second maxilliped on right side, lateral view. H. Third maxilliped on right side, lateral view. 1. Fourth maxilliped on right side, lateral view. J. Fifth maxilliped on right side, lateral view. K. First pereiopod on right side, lateral view. L. Second pereiopod on right side, lateral view. M. Third pereiopod on right side, lateral view. N. Mandible. O. First abdominal pleopod on right side, ventral view. P. Fifth abdominal pleopod on right side, ventral view. Q. Dactylus, propod and carpus of first maxilliped on right side, lateral view.

PYNE-Larval Characters of Squilla armata 141 TABLE 3.-Setation of Pleopods of the First and Second Propelagic and the First to Ninth Pelagic Stage Larvae of S. armata Abdominal Somite Endopod Exopod 1 2 3 4 5 1 2 3 4 5 1 p.p.l.s, 3 3 2 2 3 3 3 2 2 p.p.l.s. 5 5 5 5 8 9 9 8 1 p.l.s, 6+ 1 8+ 1 8+ 1 7+ 1 9 10 10 10 2 p.l.s. 6+ 1 8+ 1 8+ 1 8+ 1 10 11 12 13 3 p.l.s. 12+ 1 11+ 1 11+ 1 12+ 1 4 17 16 16 16 9 4 p.l.s, 12+ 3 12+ 3 12+ 3 12+ 3 9 18 17 17 17 12 5 p.l.s. 19+ 4 19+ 4 19+ 4 19+ 4 11 25 23 24 24 16 6 p.l.s, 22+ 6 22+ 6 22+ 6 22+ 6 18+ 5 30 30 30 30 18 7 p.l.s, 26+ 6 26+ 6 26+ 6 26+ 6 25+ 6 30 30 30 30 26 8 p.l.s, 31+11 31+11 31+11 31+11 30+12 38 38 38 38 32 9 p.l.s, 26+ 9 26+ 9 26+ 9 26+ 9 32+13 34 34 34 34 37 LARVAL CALENDAR A comparison of the total number of larvae collected per month with the corresponding average surface water temperature, has been illustrated in Fig. 15. A total of 2,565 larvae were examined. The ratio of pelagic larval stages present in the monthly totals is illustrated (Fig. 16). The first pelagic stage larvae appeared in large numbers in the plankton during April-May, when 55 percent and 14 percent respectively were recorded. Successive pelagic stages appeared as follows: May, 38 percent second pelagic stage; June, 21 percent third pelagic stage; July, 14 percent fourth pelagic stage; August, 29 percent fifth pelagic stage; September, 8 percent sixth pelagic stage; October, 3.7 percent seventh pelagic stage. /"-... I... ~---- \/-. _.~.- - - A _. _.. ~ JUN. JUL. AUG. S[P. ocr. NOY, 100 JAN HB H alt "PR. MAY. JUN. JUl. DtC. FIG. MONTH 15.-S. armata larval calendar, showing monthly abundance of S. armata larvae plotted against the average surface water temperature.

~ [ WOU 142 JOURNAL OF THE ROYAL SOCIETY OF NEW ZEALAND From this monthly sampling, it appears that whilst the water temperature ranged between 9-14.5 C, the developmental period of the first seven pelagic larval stages occupies seven months (April-May to October). No complete developmental sequence from the first through to the ninth pelagic stage was recorded. Despite the appearance of the first pelagic stage larvae in the samples for nine months of the year, it would appear that their survival rate declines rapidly in the latter months. During November, 36 percent (22 larvae) and December, 100 percent (five larvae) first pelagic stage larvae were recorded, no pelagic stage larvae were recorded for the months of January and February. This steady decline in pelagic larval stages, and their total absence during the summer months may be attributed to the increased water temperature during this period. NOTES ON THE BEHAVIOUR OF LARVAL S. armata Until recently, little was known of the habits of stomatopod larvae, as they were found difficult to keep alive in the laboratory. Recently, however, Alikunhi (1950) and Gohar and Al-Kholy (1957), were able to observe the habits of the late pelagic larval and early juvenile stages. Similar observations were possible during this present study along with observations on the behaviour of the propelagic and first pelagic stages. wu ( H... Il... Z 0 ~ r ~ IWAY cr : ' I,VIii[ '" - Q. '" 0 I JU\ " ~ cr <t..j IL 0 '"... <t " I Z Q. ~ IHO '"U '"...ue;usr I sunwlna cr ' OCI08 1:1 I - "' 9 A" E}C 4 n P E LA~ IC LA RVAL STAGES. 'D(Ut.lI9OI' FIG. 16.-The percentage frequency of occurrence for each pelagic larval stage, per month, from Kau Bay (Wellington Harbour).

PYNE~Larval Characters of Squilla armata 143 ACTIVITY OF THE FIRST AND SEOOND PROPELAGIC LARVAE During the first 4-6 days after hatching, the activity of the first propelagic larva appeared to be restricted to bobbing up and down on the bottom of the hatching tray, the larva moving only a short distance away from the egg mass, generally in a direction away from the source of light. Such bobbing action was performed by the flexing and extending of the abdomen and telson. In one instance, it was observed that the first propelagic larva, although performing the bobbing action, remained grouped in a cluster around the remains of the egg mass, which was situated in a sand hollow that had been prepared by the female during the period of incubation. Despite the first four pairs of pleopods being functional for locomotion at the time of hatching, swimming in the true sense was rarely observed. By comparison with the first propelagic stage, the second propelagic larva was observed actively swimming, the thoracic region slightly inclined and the abdomen and telson horizontal, with the pleopods acting as the main organ of propulsion. This is notably characteristic of the adult swimming posture. Active swimming seldom persisted for more than one minute, and W2S usually followed by a longish period of rest on the bottom of the rearing container. LARVAL REACTIONS TO LIGHT All larval stages displayed a photonegative response to light. When the light intensity was reduced on one side of the rearing container only, the larvae responded almost immediately by moving to the shaded side. When the light intensity was reduced over the whole area of the container, activity ceased, the larvae coming to rest on the bottom and subsequently making only feeble attempts to move about. Larvae were not able to survive short exposures (5-10 minutes) to strong artificial light or sunlight. During larval rearing experiments the water temperature was maintained at 13.5 C by a cooling jacket, but larvae exposed to the above light treatment died within twelve hours, whereas larvae kept under similar conditions in subdued light, lived for an average of 30 days. It is important, therefore, to keep the larvae away from direct light both in the rearing tanks and during microscopic examination. LARVAL REACTIONS TO DIFFERING WATER TEMPERATURES Larvae kept in total darkness tolerated water temperatures between 8-20 C for several days. It was found that very few larvae moulted when kept in total darkness at temperatures below 12 C or above lsoc, however, large numbers moulted when kept at temperatures between 12-1SoC. Thus. in all rearing experiments where still water was used, the water temperature was maintained at 13.SoC. The longest period of survival under these conditions was 186 days. BURROWING TENDENCY OF THE NINTH PELAGIC STAGE LARVAE The ninth pelagic stage larvae exhibited the characteristic adult tendency towards the construction of burrows when sand was introduced into half of the rearing container. After preliminary probings, the ninth pelagic stage larvae spent more and more time on the sand. These larvae were observed to scoop and dispose of sand grains using the maxillipeds in a manner very similar to the adult. Repetition of this activity in the same area, resulted in the excavation of a small hollow in the sand. When small stones were introduced on to the sand, holes were excavated beneath the stones, but a distinct preference was shown by the larvae to occupy the exposed hollows rather than those under the stones. LARVAL FEEDING HABITS During the first 9-12 days the two propelagic larval stages undoubtedly subsisted on yolk retained from the egg, as the paired mandibles, maxillula and maxilla are not functional. Brooks (1891) observed that the propelagic larva of Gonodaetylus oerstedii (identified as G. chiragra), settled upon unidentified nudibranch eggs which

144 JOURNAL OF THE ROYAL SOCIETY OF NEW ZEALAND he regarded as a source of food material for the larva. Gurney (1937) and Manning and Provenzano (1963), however, regard the mouth parts of G. oerstedii propelagic larva to be non-functional, the larva subsisting during this period on the retained yolk material. These latter findings corroborate the opinion held by the author with regard to S. armata propelagic larva. In the first pelagic larval stage all the yolk material has disappeared, and the mandibles, maxillula, and maxilla are functional. It would appear that the larvae are now dependent on capturing their own food material. Successful results in laboratory feeding experiments were met with in the seventh to ninth pelagic stages only. These late stage larvae showed increased activity with the introduction of food into the rearing containers, swimming rapidly towards the food, striking forwards with the large pair of raptorial limbs. Once the food was grasped by the raptorial limbs, it was drawn towards the mouth where it was transferred to, and held by, the first, third, fourth and fifth maxillipeds. Due to the translucent nature of the larva, it was possible to observe the food being masticated. It was necessary on occasions, to leave food in the rearing container for short periods of time as it was not always consumed immediately, and often the food, although accepted by the larva, was not eaten. Instead it was torn apart and scattered around the rearing container in many pieces. CANNIBALISTIC TENDENCIES OF THE LARVAE When two different stage larvae occupied the same rearing container, there was a general tendency for the late stage larvae to attack the smaller, earlier stage larvae. This generally resulted in the death of the smaller larvae, but, only on two occasions, was the attacked larva eaten by the attacker. By comparison, Alikunhi (1950) stated that, "cannibalism is rather pronounced in the group and if more than one specimen are (sic) kept in an aquarium and if anyone of them undergoes a moult, it usually falls an easy victim to the predatory leanings of its brethren. This destructive tendency is manifested also when specimens of differing sizes are kept together in an aquarium, the smaller one being preyed upon by the larger ". DISCUSSION The length of larval life is not known for any stomatopod and the number of propelagic and pelagic stages for any given species is an estimate. Caution must therefore be exercised in those accounts of larval development based on plankton material alone, until more evidence is obtained on the early stages by hatching the eggs of known species. Manning and Provenzano (1963) described three propelagic stages for Gonodactylus oerstedii Hansen, Giesbrecht (1910) described nine pelagic stages for Lysiosquilla eusebia and two propelagic stages for Squilla mantis, while Komai and Tung (1929) described nine pelagic stages for Squilla oratoria. In the present study, two propelagic and nine pelagic stages have been described and illustrated for Squilla armata. I must emphasise the fact that the first propelagic larva was not reared through to metamorphosis in the laboratory and recourse to plankton material was necessary. Despite the lack of a complete reared series of larvae, it is possible to give an estimate of larval life based on the duration of those stages which were successfully reared from hatching, plus the life-span of those which were collected alive from the plankton and maintained in the laboratory. The larvae spent 9-12 days in the propelagic stages, a maximum of 186 days in pelagic stages 1 to 7, and at least 31 days in each of the final pelagic stages 8 and 9. Thus, the duration of development from hatching to late in the final pelagic larval stages may be estimated as being about 258-260 days. While studying the larval stomatopods as larvae and not as adults, Giesbrecht (1910) noted that there were two distinct larval types at hatching, to which he gave the names "pseudozoea" and " antizoea ", defining them as:

PYNE-Larval Characters of Squilla armata 145 a. Pseudozoea-hatching with eyes pedunculate; antennules biramous; thoracic somites with uniramous appendages on the first two somites only; abdomen divided into six segments, the first four or five of which have each a pair of biramous pleopods. Develops into a larva either of erichthus or alima type. b. Antizoea-hatching with eyes sessile; antennules uniramous; first five thoracic sornites provided with biramous appendages; abdomen unsegmented or only partially segmented; abdomen with single pair of appendages or none at all. Develops into a larva of erichthus type. The two forms of development, "erichthus" and" alima ", are defined as: a. Alima-telson with four or more intermediate denticles; antennular somite with median spine; posterolateral spine of carapace with accessory spinules; eye-stalk generally long; basis and exopod of antenna elongated; pleopods 1-5 without setae on border of proximal part of exopod; exopod of uropod longer than endopod; youngest larva with four pairs of pleopods only. b. Erichthus-telson with one intermediate denticle; antennular somite without median spine; accessory spinules absent on posterolateral carapace spine; eye-stalk short; basis and exopod of antennae generally thick-set; setae present on proximal margin of pleopods 1-5; youngest larva with five pairs of pleopods. After four or five moults, Giesbrecht (1910) noted that both pseudozoea and antizoea type larvae develop into a common larval type or synzoea, with all five pairs of maxillipeds, three pairs of pereiopods, five pairs of pleopods and a pair of uropods. Using as a criteria the type of development and the type of larva, Giesbrecht (1910) classified the stomatopod larva into three groups: a. LysiosquiJIinae-first larva of antizoea type, developing into an erichthus larva. Lysiosquilla and Coronida. b. Gonodactylinae-first larva a pseudozoea with five pairs of pleopods. Developing into an erichthus larva. Gonodactylus and Odontodactylus. c. SquiIlinae-first larva a pseudozoea with four pairs of pleopods. Developing into an alima larva. Squilla. Despite the fact that only two genera, Squilla and Gonodactylus have been hatched from the egg, this system of larval classification has been retained. Manning (1963) considers, "it is rather unfortunate that a subdivision of the family has been made on the basis of characters of larval form only. Knowledge of representative early larvae in each of the known genera through complete and accurate laboratory rearing, coupled with the rearing of planktonic postlarvae through metamorphosis is needed before we can even begin to set up classification of larvae ". Laboratory hatching of S. armata eggs during this study has clearly illustrated the possession of both pseudozoea and alima diagnostic characters by the first propelagic stage, viz., Pseudozoea: antennules biramous; eyes pedunculate; uniramous appendages present on the first two thoracic somites only; abdomen fivesegmented, sixth abdominal segment fused with telson; paired biramous pleopods present on the first four abdominal somites only. Alima: telson with 5-7 intermediate denticles; basis and exopod of antenna elongate. The remaining diagnostic characters of the alima type larva appear in the development of S. armata larva as follows: Second propelagic larva: antennular somite with median spine on ventral aspect; eye stalk generally long. First pelagic larva: posterolateral spine of carapace with 6-16 proximal spinules, arranged spirally. On the basis of these findings and to avoid further confusion, no attempt has been made to define the larval stages of S. armata in terms of the larval classification proposed by Giesbrecht (1910).

146 JOURNAL OF THE ROYAL SOCIETY OF NEW ZEALAND ACKNOWLEDGMENTS I am grateful to Professor L. R. Richardson, under whose guidance and supervision this study was begun. I am also grateful to Professor J. T. Salmon, who saw this study through to completion. I wish to thank Dr R. B. Pike, Dr J. C. Yaldwyn, Dr D. Griffen, Professor J. A. F. Garrick, and Dr A. N. Baker for their valuable criticism and comments, and also the technical staff of the Zoology Department of Victoria University of Wellington, for their assistance in the collection of material from Wellington Harbour. REFERENCES ALIKUNHI, K. H. 1950. Observations on some larval and postlarval stomatopods. Journal Bombay Natural History Society 49( I): 101-107, 2 pls. BIGELOW, R. P. 1894. Report on the Crustacea of the Order Stomatopoda collected by the steamer" Albatross" between 1885 and 1891, and on other specimens in the U.S. National Museum. Proceedings United States National Museum 17: 515-18. BROOKS, W. K. 1879. The larval stages of Squilla empusa Say. Johns Hopkins. University of Chesapeake, Zoological Laboratory Scientific Results 1878: 143-70, pis. 9-13. 1886. Voyage of H.M.S. "Challenger", Stomatopoda, 16: 1-116, pis. 1-16. 1891. Habits and metamorphosis of Gonodactylus chiragra. In Brooks, W. K., and F. H. Herrick, Embryology and metamorphosis of the Macrura. Memoirs Natural Academy Sciences 5(4): 353-60, pis. 1,3, 14, 15. CLAUS, C. 1871. Die Metamorphose der Squilliden. Abhandlungen der K. Gesellschajt W issenschaften Gottingen. 16: 111-63, 35 pis. CLARK, G. 1869. On the Squilla of Mauritius. Proceedings of the Zoological Society of London, 1869: 1. FAXON, W., 1882. Selections from Embryological Monographs, I. Crustacea. Memoirs Museum of Comparative Zoology, Harvard University, 9 (1). FOXEN, G. E. H. 1932. Report on stomatopod larvae, Cumacea and Cladocera. Scientific Reports, Great Barrier Reef Expedition 4( 11): 375-98, 10 figs. 1939. Stomatopod larvae. Sci. Reps. John Murray Exped. 6(6): 251-66, 4 figs. GIESBRECHT, W. 1910. "Stomatopoda." Fauna und Flora Neapel Monograph, 33: vii, 1-239, 11 pis. GOHAR, H. A. F., and A. A. AL-KHOLY 1957. The larval stages of three stomatopod Crustacea. Publication Marine Biological Station, Ghardaqa 9: 85-130, 23 pis. GURNEY, R. 1937. Notes on some decapod and stomatopod Crustacea from the Red Sea. III-V. Proceedings Zoological Society London 107B(3): 319-36,8 pis. 1946. Notes on stomatopod larvae. Proceedings Zoological Society London 116 ( 1) : 133-75, 14 figs. KOMAI, T. 1924. Development of Squilla oratoria de Hann. I. Change in External Form. Memoirs of the College of Science, Kyoto Imperial University, 1, 13(3): 273-83. KOMAI, T., and Y. M. TUNG 1929. Notes on the larval stages of S. oratoria, with remarks on some other stomatopod larvae found in the Japanese seas. Annotationes Zoologicae [aponenses 12: 187-237, pis. 1-9. LEBOUR, M. V. 1934. Stomatopod larvae. Resultats scientifiques du voyage aux Indes orientales Neerlandaises de LL.AA.RR. Le Prince et la Princesse Leopold de Belgique, 3 (16): 11-17, figs. 1-5. MANNING, R. B., and A. J. PROVENZANO JR. 1963. Studies on development of stomatopod Crustacea. 1. Early larval stages of Gonodactylus oerstedii Hansen. Bulletin of Marine Science, Gulf and Caribbean 13(3): 467-87, figs. 1-8. MAYER, P. 1877. Carcinologische Mitteilungen. Mitteilungen Zoologischen Station Neapel, 1: 40.--53. SERENE, R. 1954. Observations Biologiques sur les Stomatopodes. Memoirs Institute Oceanographique de Nhatrang 8: 1-93. TOWNSLEY, S. J. 1953. Adult and larval stomatopod crustaceans occurring in Hawaiian waters. Pacific Science 7(4): 399-437, figs. 1-28. WEAR, R. G. 1965. Zooplankton of Wellington Harbour, New Zealand. Zoology Publications, Victoria University of Wellington No. 38 1-31, 9 figs. REX R. PYNE Fisheries Division Department of Primary Industries Brisbane Australia