Serranidae: F III A1

Acanthistius joanae Heemstra 2010.

Whiteblotch koester

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








51% of NL


Egg: The identifying features of this egg are size, segmented yolk and just a few scattered stellate yellow pigment spots on the yolk (A). The developing embryo has 6-7 yellow pigment patches along the body. Black pigment spots are mostly dorsal on the embryo. There are a few black pigment spots on the oil globule but none on the yolk. The oil globule is usually pale amber to clear. Segmentation of the yolk is often confined to the edge. Incubation time is about 40 hours (22-23°C). This is the only serranid I have found, with a segmented yolk.

Larva: The distinctive yellow pigment pattern of the 1-day (B) and more especially the 3-day (C) larvae, quickly confirm the identity of Acanthistius. The 5-day larva develops a pair of white patches into the finfolds in mid-body, which has been seen in other serranid larvae (E). At 11 days the larva was just starting flexion (F), while at 21 days the larva was fully post-flexion (G). At 75 days the juvenile is assuming the colours of the adult (I). B 1 day, C: 2 days, D: 3 days, E: 5 days, F: 11 days, G: 21 days, H: 37 days, I: 75 days (22°C).

The larva proved quite easy to rear, despite seldom taking large numbers of eggs. Adults are fairly common on reefs at 30-40m off Park Rynie, but are usually only seen singly. Fourteen larvae hatched from this egg, have been barcoded, matching 5 adults collected locally (BOLD).

Spawning occurs all year round, with a definite increase in the colder months, from April to October (blue graph). They were not seen in the DHM samples. This egg has shown a steady decrease over the study period (white graph).

Linked samples









 Among the more common eggs in the Park Rynie linked samples, this was the egg with the highest percentage offshore (90%). This is surprising, given that they are fairly common on reef at 30-40m (personal observations), but perhaps reflects a wider distribution across the shelf. See Section 7.3 and Table 1 of the Introductory Notes, for more information on the linked samples.