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Larvae Information Summary for
Ceratoscopelus townsendi
| Main Ref: | Moser, H.G. and E.H. Ahlstrom 1996 | |||
Yolk-sac larvae
| max | min | mod | Ref. | |
| Length at birth (mm) | 2.2 | |||
| Preanal L. % TL | 61 | 40 |
| Place of development | planktonic | |||
| Larval area | California Current region; Agulhas Current Region | |||
| Yolk-sac | Ref: | |||
| Yolk | Oil globules | |||
| Rows on tail | ||||
| Other melanophores on tail | ||||
Post larvae
| Striking feature | light organs | |||
| Striking shape lateral | normal (not striking) | dorsal | compressed | |
| Striking feature | light organs | |||
| Shape of gut | spherical or gut loop | |||
| Gas bladder early | pigmented | late | ||
| Spinal armature early | no spines | late | no spines | |
| Pigmentation early | ||||
| Rows on tail | no rows | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on trunk | |||
| Pigmentation late | ||||
| Rows on tail | no rows | |||
| Other melanophores on tail | no other melanophores | |||
| Melanophores on head + trunk | melanophores on head + trunk | |||
| Urostyle region early | unpigmented | late | unpigmented | |
| Peritoneum | without melanophores | |||
| Pectorals | normal without melanophores | |||
| Pelvics | fin rays only without melanophores | |||
| Moderately slender body; gut to about midbody, slightly sigmoid; head relatively small; eyes large, slightly elliptical, with lunate sliver of choroid tissue in larvae >5.0 mm; snout acute, becoming blunted in larvae >14.5 mm; lacks pigment on mid-lateral region of gut and on anterior ventral margin of gut (present in Diaphus theta, Stenobrachius leucopsarus, and Triphoturus); lacks hypural melanophore (present in Diaphus). Distinguished from other myctophids with round eyes by: eye elliptical in preflexion larvae (although not perfectly round, the eye is easily differentiated from the narrow eyes of larval Myctophinae); single spot at anus; preflexion larvae with about 11 postanal ventral melanophores. Appearance of photophores: Br2(7.0 mm SL), Vn(7.8 mm SL), PLO (8.7 mm SL; develop and remain at pectoral fin base throughout larval period but at transformation they migrate dorsally to just below the lateral line), PO5 (9.0 mm SL); during transformation the remaining photophores develop sequentially; Pigmentation: Preflexion: 6-11 dashes (average about 8) in postanal median ventral series; above developing gas bladder by 5.0 mm; pair on terminal section of gut. Flexion: postanal series coalesces to 1 at anal fin insertion by end of stage; embedded series of 1-4 (usually 2 or 3) above vertebral column in caudal peduncle region. Postflexion: embedded in otic region in some larvae >10.5 mm (present in most larvae >16.0 mm); 1 medially above hindbrain in some larvae >12.5 mm. Sequence of fin development: caudal, anal, dorsal; pectorals; pelvics. | ||||
Meristic characters
| max | min | mod | Ref. | |
| Total number of vertebrae | 38 | 35 | 31442 |
| L 1st feeding | Ref. | Months of presence of larvae | ||||
| max | Jan | Feb | Mar | Apr | ||
| min | May | Jun | Jul | Aug | ||
| mod | Sep | Oct | Nov | Dec | ||
| Similar species 1 | 10238Benthosemapterotum |
| Remarks | |
| No pigmentation on the cleithral symphysis in Ceratoscopelus; melanophores on the ventral midline more numerous in C. townsendi than in B. pterotum larvae. Sequence of photophore development in Ceratoscopelus: Br2, Vn, PLO, PO5 and in B. pterotum: Br2, DN, PO5, PVO. Smaller and less rounded eyes (especially in smal larvae) in Ceratoscopelus than in Bolinichthys. | |
| Water parameters Metric characters |
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