Mm In Notochord Length Research Articles

Sex determination by ultrasonography prior to artificial breeding of the pufferfish Arothron manilensis (Tetraodontiformes, Tetraodontidae).

Artificial breeding was induced in the pufferfish Arothron manilensis following ultrasonographic sex determination. Hormonal treatment of mature male and female specimens followed the collection (and measurement) of fully developed eggs by cannulation. Fertilized eggs (0.85 ± 0.02 mm diameter) were spherical, demersal and individually adhesive. Hatching occurred 5 days after fertilization, larvae being 2.23 ± 0.15 mm in total length and 2.08 ± 0.14 mm in notochord length. The larvae had all died within 14 days of hatching. To improve artificial breeding techniques for A. manilensis, it is necessary to determine more appropriate timing for hormone injection, as well as feeding nutrient-enhanced SS type Brachionus sp. to newly hatched larvae.

The larval attachment organ of the bowfin Amia ocellicauda Richardson, 1836 (Amiiformes: Amiidae) and its phylogenetic significance.

Larval attachment organs (LAOs) are unicellular or multicellular organs that enable the larvae of many actinopterygian fishes to adhere to a substrate before yolk-sac absorption and the free-swimming stage. Bowfins (Amiiformes) exhibit a sizable LAO on the snout, which was first described in the late 19th and early 20th centuries. In this study, we document the LAO of Amia ocellicauda (Richardson, 1836) using a combination of scanning electron microscopy (SEM) and light microscopy, and histochemistry. We examined material representing three stages with SEM ranging in size from 5.8 to 11.2 mm in notochord length and one stage histochemically. We compare the LAO of A. ocellicauda to that of the lepisosteid Atractosteus tropicus Gill, 1863 and show that although the LAOs of A. ocellicauda and A. tropicus are both super-organs, the two differ in the ultrastructure of the entire organ. A. ocellicauda possesses two distinct lobes, with the organs arranged on the periphery with none in the middle, whereas A. tropicus also possesses two lobes, but with the organs scattered evenly across the super-organ. The individual organs of A. ocellicauda possess adhesive cells set deep to support cells with the adhesive substance released through a pore, whereas A. tropicus possesses both support cells and adhesive cells sitting at a similar level, with the adhesive substance released directly onto the surface of the organ. We additionally provide a table summarizing vertebrate genera in which attachment organs have been documented and discuss the implications of our study for hypotheses of the homology of attachment organs in the Holostei.

Spawning, Embryology, and Larval Development of the Milletseed Butterflyfish Chaetodon miliaris in the Laboratory

AbstractAs part of the Rising Tide Conservation effort to advance marine ornamental aquaculture the Milletseed Butterflyfish Chaetodon miliaris (also known as Millet Butterflyfish) was chosen as a candidate species for developing butterflyfish aquaculture methodologies. Thirty‐five mature Milletseed Butterflyfish were imported to University of Florida's Tropical Aquaculture Laboratory in Ruskin, Florida, from The Rainbow Reef exhibit at Aulani, a Disney Resort and Spa in Ko Olina, Hawaii, for evaluation. Spawning behavior was documented through personal and video observation five times. Eggs were collected immediately after spawning and checked for fertilization, and a sample of 100 ± 10 eggs were photographed every hour until hatching to document embryological development. Larval development was monitored through multiple rearing trials. Larvae were stocked into 128‐L, cylindrical, rearing tanks at 15–20 larvae/L and fed nauplii of the copepod, Parvocalanus crassirostris, and the microalgae, Tisochrysis lutea, was added to green the water. Samples of larvae were measured using notochord length from the tip of the snout to the edge of the notochord prior to flexion, SL from the tip of the snout to the edge of the hypural plate, and TL. Spawning occurred in broodstock tanks between one dominant male and a single female with a large, swollen abdomen. Eggs of the Milletseed Butterflyfish were small, spherical, pelagic, and transparent and hatched after a 28‐h period at 25.5°C. Newly hatched larvae had unpigmented eyes and a closed digestive tract and measured 1.20–1.24 mm in notochord length. Larvae were capable of feeding at 4 d posthatch (dph), fully absorbed the yolk sac by 7 dph, and began forming the tholichthys plates at 24 dph. Larvae survived to 44 dph in preliminary culture trials and measured 6.49–6.56 mm TL. Further investigation into the culture requirements of Milletseed Butterflyfish will supply a crucial base for developing aquaculture protocols for other marine ornamental species.

Early developmental stages of the scorpaenid fish, Scorpaena miostoma, reared in the laboratory

Embryonic development and morphology of the eggs, egg masses and larvae of the scorpaenid fish,Scorpaena miostoma are described on the basis of the laboratory-reared specimens. The gelatinous egg mass is not bilobed but simple, oval and balloon-like in shape. It usually floats at or near the surface. The individual egg is colorless and ovoid in shape, measuring 0.86 × 0.75 mm. Hatching occurs between ca. 34 and 40 hours after spawning at the water temperature of 22–24°C. A newly hatched larva measures 1.55 mm in notochord length and has ca. 25 myomeres. The finfold is balloon-like in shape and almost completely covers the larval body. Minute “cell-like” granules scatter on the findfold.

황해 참서대(Cynoglossus joyneri) 자어의 형태기재

Four specimens of Cynoglossus larvae (3.2-7.3 mm in notochord length, NL) collected from the middle Yellow Sea in August, 2008 were identified as Cynoglossus joyneri larvae based on morphological characteristics; (1) the two elongated dorsal fin rays on the parietal region, (2) protruded abdomen, (3) no melanophores on the mediolateral trunk and tail. Larva of 3.2 mm NL is compressed with a little big head and tapering, long tail. Larva of 7.0 mm NL has 115 dorsal fin and 85 anal fin rays, which are the same to those of adult. Larva of 7.3 mm NL tended to have concave part in the fringe of forehead, in which left-side eye may move to the other side.

Developmental and microbiological analysis of the inception of bioluminescent symbiosis in the marine fish Nuchequula nuchalis (Perciformes: Leiognathidae).

Many marine fish harbor luminous bacteria as bioluminescent symbionts. Despite the diversity, abundance, and ecological importance of these fish and their apparent dependence on luminous bacteria for survival and reproduction, little is known about developmental and microbiological events surrounding the inception of their symbioses. To gain insight on these issues, we examined wild-caught larvae of the leiognathid fish Nuchequula nuchalis, a species that harbors Photobacterium leiognathi as its symbiont, for the presence, developmental state, and microbiological status of the fish's internal, supraesophageal light organ. Nascent light organs were evident in the smallest specimens obtained, flexion larvae of 6.0 to 6.5 mm in notochord length (NL), a developmental stage at which the stomach had not yet differentiated and the nascent gasbladder had not established an interface with the light organ. Light organs of certain of the specimens in this size range apparently lacked bacteria, whereas light organs of other specimens of 6.5 mm in NL and of all larger specimens harbored large populations of bacteria, representatives of which were identified as P. leiognathi. Bacteria identified as Vibrio harveyi were also present in the light organ of one larval specimen. Light organ populations were composed typically of two or three genetically distinct strain types of P. leiognathi, similar to the situation in adult fish, and the same strain type was only rarely found in light organs of different larval, juvenile, or adult specimens. Light organs of larvae carried a smaller proportion of strains merodiploid for the lux-rib operon, 79 of 249 strains, than those of adults (75 of 91 strains). These results indicate that light organs of N. nuchalis flexion and postflexion larvae of 6.0 to 6.7 mm in NL are at an early stage of development and that inception of the symbiosis apparently occurs in flexion larvae of 6.0 to 6.5 mm in NL. Ontogeny of the light organ therefore apparently precedes acquisition of the symbiotic bacteria. Furthermore, bacterial populations in larval light organs near inception of the symbiosis are genetically diverse, like those of adult fish.

Reproductive Biology and Early Development of Two Species of Sleeper, Eleotris acanthopoma and Eleotris fusca (Teleostei: Eleotridae)1

Reproductive biology and early development of two species of sleepers, Eleotris acanthopoma Bleeker, 1853, and E. fusca (Forster, 1801), were investigated in streams on Okinawa Island in southern Japan. Gonadal examination and morphology of the genital papillae indicated that E. acanthopoma matured at a smaller body size (ca. 28 mm in standard length) than E. fusca (ca. 50 mm). Mature ovaries were composed of oocytes that could be categorized into two size classes. Larger females of both species had several hundred thousand developed oocytes in the larger size class and may spawn them at one or several consecutive spawning events. Egg masses of both species were found in habitats typically occupied by adults and were deposited, often sparsely, on the underside of objects. Form of the egg masses and morphology of eggs and newly hatched larvae of both species were almost identical. Eggs were a nearly spherical pyriform in shape, with the widest diameters measuring approximately 0.4 mm. Newly hatched larvae were very small (1.0–1.4 mm in notochord length) and undeveloped. The mouth opened and the eyes became pigmented 3 days after hatching, and all of their yolk was consumed 4 days after hatching. Reproductive strategies of both species were characterized by high fecundity through production of small eggs and small newly hatched larvae, with high fecundity likely to mitigate the presumed increased risk associated with widespread larval dispersal.

Eggs and larvae of Awaous melanocephalus (Teleostei: Gobiidae)

The morphology of eggs and larvae of Awaous melanocephalus is described. The eggs measured 0.33–0.35 mm in long-axis diameter and 0.32–0.34 mm in short-axis diameter. Newly hatched larvae (0.90–0.99 mm in notochord length, NL; 0.93–1.04 mm in total length, TL) were poorly developed, lacking a mouth and having a large yolk sac and unpigmented eyes. The mouth opened and the eyes became fully pigmented 3 days after hatching (1.78–2.00 mm NL, 1.88–2.10 mm TL). The yolk sac was completely absorbed 5 days after hatching at a water temperature of 27°–28°C.

Larval and juvenile development of Lestidiops sphyraenopsis Hubbs, 1916 (Aulopiformes: Paralepididae) in the western North Pacific, with a reexamination of the holotype of Stemonosudis molesta (Marshall, 1955)

The early life stages of Lestidiops sphyraenopsis (Paralepididae) are described on the basis of 14 specimens [7.8 mm in notochord length (NL)–88.6 mm in standard length (SL)] collected from the western North Pacific, and the holotype of Stemonosudis molesta is reexamined. Larval L. sphyraenopsis occurred in the Kuroshio waters, and juveniles were taken in the Kuroshio–Oyashio transition waters. Diagnostic characters of larval and juvenile L. sphyraenopsis are 96–101 myomeres; 27–31 anal fin rays; 4–9 peritoneal pigment sections in larvae (7.8 mm NL–27.3 mm SL); dorsal and anal pigment patches present; and anus located anterior to a vertical through dorsal fin origin. Stemonosudis molesta, known only from the holotype from the South Pacific, is similar to immature specimens of L. sphyraenopsis, but can be clearly distinguished from the latter by having higher vertebral counts (105 vs. 96–101) and by morphometric and pigment differences. Consequently, S. molesta is a valid species, and the distribution of L. sphyraenopsis is restricted to the North Pacific.

Uncisudis posteropelvis, a new species of barracudina (Aulopiformes: Paralepididae) from the western North Pacific Ocean

Six specimens (2 flexion larvae: 9.5–10.4 mm in notochord length; 4 postflexion larvae: 12.3–18.2 mm in standard length) collected from the western North Pacific are tentatively ascribed to the genus Uncisudis of the tribe Lestidiini of the subfamily Paralepidinae (Paralepididae) in sharing remarkably elongate and filamentous pelvic fin rays, their tips reaching the origin of the anal fin. They are described as Uncisudis posteropelvis sp. nov. in uniquely having the insertion of pelvic fins closer to the origin of anal fin than to the posterior end of dorsal fin base among lestidiine species. Addition to this character, the new species has remarkably elongate and filamentous dorsal fin rays, the short distance between anus and origin of anal fin (4.2–6.1% of standard length, SL), the posteriorly located pelvic fins (prepelvic length 69.4–71.5% SL), dorsal fin rays 10, anal fin rays 28–29, myomeres 41–42 + 38–40 = 80–81 (vertebrae 38 + 41 = 79), and peritoneal pigment spots 11–12. The occurrence of larvae differing in pigment pattern from the present new species suggests another undescribed species of Uncisudis in the western South Pacific.

Ontogeny of the mandarinfish Siniperca chuatsi (Perciformes: Sinipercidae) reared in aquarium

Early-stage morphologies of the mandarinfish Siniperca chuatsi are described on the basis of an ontogenetic series of reared specimens in an aquarium. Spherical eggs (diameter 1.70–1.82 mm) with a single oil globule (0.40–0.48 mm) were free-demersal and easily floated when agitated. Hatching occurred about 3 days after spawning at about 24°C. Newly hatched larvae (3.8–4.2 mm in notochord length: NL) had many melanophores on the yolk sac. After reaching ca. 5.5 mm NL (8–9 + 19–20 = 27–28 myomeres), larvae had almost completely absorbed the yolk, possessed a large mouth and sharp teeth, and were starting to prey on other fish larvae. Three large preopercle spines appeared at ca. 5.5 mm NL, five spines by ca. 8.5 mm NL, and eight by ca. 21 mm in standard length (SL). The interopercle bore a single spine at ca. 8.5 mm NL and two spines at ca. 13.5 mm SL. A single spine appeared at the supracleithrum and another at the opercle at ca. 10 mm SL. Dorsal fin spines and pelvic, anal, and caudal fins were completed at ca. 10 mm SL. Dorsal fin rays and pectoral fins were completed at ca. 13.5 mm SL. Four ontogenetic characters (free-demersal eggs, large jaws with large teeth, conspicuous head spination, and precocious completion of dorsal fin spines) are rare among freshwater percoids.

The eggs and larvae of the giant mudskipper, Periophthalmodon schlosseri , collected from a mudflat in Penang, Malaysia

Eggs of the giant mudskipper, Periophthalmodon schlosseri were collected from a burrow in Penang, Malaysia, in November 1998, and hatched larvae were reared in the laboratory. The eggs were demersal with adhesive filaments and elliptical in shape (0.83–1.43 mm in long-axis diameter). Newly hatched larvae (2.1–2.6 mm in notochord length) possessed a yolk sac. The number of myomeres was 10 + 17 = 27. The mouth and anus were already opened. The larvae started feeding one day after hatching and completely absorbed the yolk by the third day at a water temperature of 24.5–28.0°C.

Osteological development in the Japanese sardine,Sardinops melanostictus

The development of all osteological elements, except scales, of the Japanese sardine,Sardinops melanostictus, is described from newly-hatched larvae to adult fishes. Newly-hatched larvae lacked osteological elements. Part of the head skeleton began to develop in 53 hour old larvae (4.2 mm in notochord length [NL]). Larvae at the first-feeding stage (77 hours, 5.5 mm NL) possessed several elements of the head skeleton and pectoral fin supports. In a 10.5 mm NL specimen, part of the caudal and dorsal fin supports were apparent. The centra appeared in specimens 18–22.7 mm in standard length (SL). Gill rakers were first observed in the lower branchial arches at 13 mm NL and spine-like processes with spiny nodules from about 25 mm SL. The distance between the predorsal and first dorsal proximal radial relative to SL rapidly decreased with forward translocation of the dorsal fin and became constant beyond approximately 34 mm SL. At this stage, most basic osteological elements were established. Completion of the osteological structure was characterized by the disappearance of the dentary teeth at 60–70 mm SL. Based on the osteological development, ontogenetic intervals consisting of four periods and eight phases were recognized.

Feeding Habits of Japanese Flounder (Paralichthys olivaceus) Larvae in the Western Part of Wakasa Bay, the Japan Sea.

The feeding habits of Japanese flounder Paralichthys olivaceus larvae collected in the western part of Wakasa Bay were studied. Gut contents analysis was conducted on 393 larvae (from 2.3 to 7.9mm in notochord length) collected with an opening and closing bongo-type larva net (60cm diameter and 200μm mesh) from 12 May to 10 June 1986.The percentage of larvae with foods (feeding incidence) was low (25%) at the first feeding stage (stage A), in which the larvae were mainly fed on small copepod nauplii and invertebrate eggs. Feeding incidence increased with development and reached over 90% at stage C. Associated with the increase in feeding incidence, an increase in the size and size range of prey was observed. Main food items also shifted to Appendicularia (Oikopleura spp.) and/or large copepod nauplii (mainly Calanus sp.).The size of main prey organisms changed at each developmental stage. At stage B prey shifted from small copepod nauplii to the large Oikopleura spp. Japanese flounder larvae enlarged their prey gradually due to this prey selection.

Laboratory studies of predation by the hyperiid amphipod Parathemisto japonica on larvae of the Japanese sand-eel Ammodytes personatus.

The ability of the hyperiid amphipod Parathemisto japonica to feed on larvae of the Japanese sand-eel Ammodytes personatus were studied in the laboratory. The number of larvae eaten by P. japonica increased with increase in predator size, up to 27.4 of 1-3-day-old larvae were consumed per 12 h under light conditions. The feeding rate became higher as the number of larvae offered was increased, showing a functional response that approached a maximum rate asymptotically. P. japonica consumed 13-15-day-old larvae (6.0-6.3mm in notochord length) to the same degree as 1-3-day-old larvae (4.7-5.1 mm in notochord length) in terms of wet weight. The feeding activity of P. japonica was higher during daytime than at night. Larger P. japonica (3.8-4.5mm in head plus thorax length) consumed from 13.1 to 36.7 1-3-day-old larvae per day and the daily ration ranged from 38.1% to 59.9%. These feeding experiments together with a field survey, suggest that predation of P. japonica has considerable effect on the survival of larval sand-eels in Otsuchi Bay and adjacent waters.

Food selection by young larval gulf menhaden (Brevoortia patronus)

Food selection by young larvae of the gulf menhaden (Brevoortia patronus) was studied in the laboratory at Beaufort, North Carolina (USA) in 1982 and 1983; this species is especially interesting, since the larvae began feeding on phytoplankton as well as microzooplankton. When dinoflagellates (Prorocentrum micans), tintinnids (Favella sp.), and N1 nauplii of a copepod (Acartia tonsa) were presented to laboratory-reared, larval menhaden (3.9 to 4.2 mm notochord length), the fish larvae ate dinoflagellates and tintinnids, but not copepod nauplii. Larvae showed significant (P<0.001) selection for the tintinnids. Given the same mixture of food items, larger larvae (6.4 mm notochord length) ate copepod nauplii as well as the other food organisms. These feeding responses are consistent with larval feeding in the northern Gulf of Mexico, where gulf menhaden larvae between 3 and 5 mm in notochord length frequently ate large numbers of dinoflagellates (mostly P. micans and P. compressum) and tintinnids (mostly Favella sp.), but did not eat copepod nauplii. As larvae grew, copepod nauplii and other food organisms became important, while dinoflagellates and tintinnids became relatively less important in the diet. Since the tintinnids and nauplii used in the laboratory feeding experiments were similar in size as well as carbon and nitrogen contents, the feeding selectivity and dietary ontogeny that we observed were likely due to a combination of prey capturability and larval fish maturation and learning.