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Larvae Information Summary for
Chanos chanos
| Main Ref: | Schuster, W.H. 1960 | |||
Yolk-sac larvae
| max | min | mod | Ref. | |
| Length at birth (mm) | 3.4 | 3.2 | 4 | 26505 |
| Preanal L. % TL | 2.6 |
| Place of development | planktonic | |||
| Larval area | Western Pacific (Philippines, Japan) | |||
| Yolk-sac | elongated pigmented | Ref: | ||
| Yolk | segmented | Oil globules | no oil globule | |
| Rows on tail | no rows | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on head + trunk | |||
| At hatching, no eye pigmentation and no fin buds are present. Eye pigmentation start to appear 36 hours after hatching and completed at 54 hours. The mouth opened at 54 hours and soon became movable (mouth width was 500 µm). Long and straight gut reaches to about 80% of BL. Pigmentation: Black pigment cells are present in the finfold except the tip of the caudal region. Pigment is also scattered in the yolk mass and on the head and body of the larva (Ref. 139). The arrangement of muscle fibers in the myotomes of Chanos larvae is parallel to the longitudinal axis of the body. Characteristic swimming behaviour: the larvae remains suspended head down in the water column near the surface, then sinks slowly, upon reaching a depth of about 5-8 cm, the larvae makes a sudden upward turn of 360° before swimming rapidly to the surface. This behaviour lasts mainly for two days. At this stage, larvae are slightly negatively bouyant (Ref. 43081). | ||||
Post larvae
| Striking feature | none | |||
| Striking shape lateral | normal (not striking) | dorsal | compressed | |
| Striking feature | none | |||
| Shape of gut | tube-like | |||
| Gas bladder early | visible | late | visible | |
| Spinal armature early | no spines | late | no spines | |
| Pigmentation early | ||||
| Rows on tail | dorsal + ventral row | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on trunk | |||
| Pigmentation late | ||||
| Rows on tail | dorsal + ventral + lateral row | |||
| Other melanophores on tail | tail partly covered with melanophores | |||
| Melanophores on head + trunk | melanophores on head + trunk | |||
| Urostyle region early | unpigmented | late | unpigmented | |
| Peritoneum | covered with melanophores | |||
| Pectorals | normal without melanophores | |||
| Pelvics | normal (i.e. small or absent) without melanophores | |||
| Yolk is completely absorbed on the 3rd day. Eyes well pigmented. Functional mouth with an opening present. At flexion, body becomes transparent and stomach contents visible. Larvae (and adults) lack teeth. Pigmentation: Pigments scattered over the upper half of the body and on peritoneal wall. Mediolateral pigment on the caudal region proceeding anteriorly. Pigmentation on head region increases. Sequence of fin development: pectoral, caudal, dorsal and anal, pelvic. | ||||
Meristic characters
| max | min | mod | Ref. | |
| Total number of myomeres | 47 | 44 | 43010 | |
| Preanal number of myomeres | 32 | 139 |
| L 1st feeding | Ref. |
Months of presence of larvae
|
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| max | 5.6 | 26505 | Jan | Feb | Mar | Apr |
| min | 3.4 | 26505 | May | Jun | Jul | Aug |
| mod | 4.5 | 26505 | Sep | Oct | Nov | Dec |
| Ease of identification: | |||
| likely to be confused with closely related species. |
| Water parameters Metric characters |
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