Ostraciidae: CM I A1

Tetrosomus concatenatus (Bloch, 1786), Lactoria fornasini (Bianconi, 1846).and another

Triangular Boxfish and Backspine cowfish

Egg diameter in µm	Number of oil globules	Diameter of oil globule in µm	Yolk texture	Perivitelline space	Position of oil globule at hatch	Gut length   at eye- pigment stage	Myomeres
1800-1900	multiple	N/A	clear	narrow	stern	50% of NL	27

Egg: When fresh, this egg is spherical, with a multiple oil globule (A). As the egg develops, the micropyle becomes raised, causing the egg to become slightly pear-shaped. The raised area becomes pimpled, speckled and opaque, while the rest of the egg surface becomes covered in yellow pigment spots (B).When floating freely, the micropyle points downwards, and the egg needs to be turned, to see it. The longest incubation period I recorded was eggs collected on the morning of 870117, hatched 870120 at 1800, a minimum of 80 hours.

Larva: The newly hatched larva is bulbous, and covered in yellow pigment spots, as was the egg (C). The oil globules may not yet have coalesced, and the anus is tucked up against the membrane that surrounds the yolk (C). The eyes and mouth are developed by day 6 (D), when all yellow pigment has disappeared (D), although they persisted in another 6-day larva (F). This was not temperature related, since both were reared at 23°C. C: NH, D: 3 days, E & F: 5 days, G: 9days.  

On one occasion I reared a Tetrosomus sp. from this egg. Shao et al (2001), report Lactoria diaphana and Ostracion meleagris as having similar eggs, though the former has a single oil globule. Ten hatched larval barcode sequences, have matched 2 adult Tetrosomus concatenatus, while another 8 have matched Lactoria fornasini (BOLD). Two larvae, of a third species, and 1 of a fourth species, have not matched any locally collected Ostraciidae, although they cluster with other members of the family in the dendrogram..

 

Spawning is all year round (blue graph), but is the sum of several species. The egg was only seen once in the DHM samples; a single egg in February 1991. The presence of eggs off Park Rynie, over the duration of the study has shown a decreasing trend (white graph). It was more common offshore, in the Park Rynie linked samples (61%), but the low percentage indicates spawning around the 20-30m depth contours. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.

linked samples	Offshore	Inshore
Eggs	362	231
Hits	169	114