Photo by Richard Steventon
Photo by Guido Zsilavecz
Male - note the tall orbital tentacles. Photo by Guido Zsilavecz
Female - note the small orbital tentacles and the pregnant look. Photo by Guido Zsilavecz
Male guarding eggs, to the right of the fish. Photo by Guido Zsilavecz
Guido has been seeing this blenny now and then at various locations in False Bay - from shallow A-Frame to 30m depths at D-Frame, far offshore. It has also been seen by Robert Wilson and Richard Steventon. It is a very skittish species, and it generally does not hang around for long when caught in the open. Getting a good photo for identification purposes is not easy; either it disappears, or it sticks to a narrow crevice or hole!
Trying to identify it has not been easy. A photo of a fish which is obviously the same species can be found in Two Oceans, as the ringneck blenny, Parablennius pilicornis. The text describing it is somewhat ambiguous, as it states that the fish is "an Atlantic species", yet the map shows its distribution as being more or less Knysna eastwards! Smiths' Sea Fishes gives the latter as the distribution. Photos in other guides, and some taken by Guido in Knysna, show a somewhat different looking species than shown in Two Oceans though. What is especially intriguing is the dark spot half-ringed by a narrow white margin (a semi-ocellus spot, using the right language) behind the eye. This spot can be seen on all individuals photographed, and is simply too distinguishing a feature not to have been mentioned in the literature - but for the ringneck blenny it isn't. This is of course not conclusive, as a local variety of the species may have it, while those further up country do not, for example. One must not forget the distribution of the species as given by Smiths': Knysna eastwards. Cape Town receives its fair share of visitors, so it is not too unusual to find them, but generally they do not stick around: they may be seen a few times in a season and then never again. This blenny however has been seen for some time now, so it appears to be a local.
Given the apparent lack of the semi-ocellus in the ringneck blenny other species were looked at, and there is a species which seems to have a similar spot, although the white half-moon is offset slightly. This species, the sailfin blenny Lipophrys velifer occurs on the Atlantic (remember what Two Oceans said?), down to Angola and possibly Namibia (according to fishbase.org). A good distance from Cape Town, and against the current, so somewhat more unlikely than a ringneck.
In discussion with Dr. Heemstra and Dr. Williams another candidate was suggested: the two-eye blenny, Chalaroderma ocellata. It occurs from Saldanha Bay to Port Elizabeth. Distribution-wise it is thus the most likely, and it has something which Guido did not notice until now (having been blinded by the semi-ocellus...) - a black spot on the base of the dorsal fin, which can be seen on Richard's photo. This feature is shown on the images in Smiths', but unfortunately no useful colour images have been found. This species was described by Gilchrist and Thompson in 1908 - but no mention of the semi-ocellus spot. It is mentioned by Barnard in his monograph on marine fishes in 1927, with the common name given as ocellate blenny, but without mentioning an ocellate spot (although the dorsal fin spot is mentioned), in JLB Smith's Sea Fishes of Southern Africa, with the same common name, by Penrith and Penrith in 1972 (unfortunately SURG does not have this paper), and in Smiths', where the common name has changed to "two-eye blenny". The "ocellate" name, and "two-eye" is intriguing - a black spot it not ocellate, and too far from the eye to be second eye - might this refer to the semi-ocellus instead?
SURG decided to investigate further by visiting the blennies again, given that we now thought we might have a location where we could see them consistently. And indeed, in the same location where Richard took his photo a whole colony of about 6 to 8 individuals was found, using the empty shells of giant barnacles, Austromegabalanus cylindricus, as homes. Most of the blennies were peeking out of their barnacles, but some swam around, including the male and female shown - the males have tall orbital tentacles, the females much shorter ones. Interestingly, in blennies males often guard the eggs, and the individual shown guarding eggs did not peep out of its barnacle like the others! We are still not closer to identifying the exact species, but it seems most likely to be Chalaroderma ocellata, given a few physiological features and its distribution which includes the Cape.
The photo by Richard was taken at A-Frame, the photos by Guido Zsilavecz at D-Frame (a reef offshore from A-Frame) and A-Frame.
Thanks to Professor Charles Griffiths (UCT), Dr. Phil Heemstra (SAIAB) and Jeff Williams (Smithsonian Institution) for information.
The Blenniidae of South Africa, JDF Gilchrist and WW Thompson. Annals of the South African Museum, Volume 6, December 1908.
A Monograph on the Marine Fishes of South Africa, Part II, KH Barnard. Annals of the South African Museum, Volume 21, October 1927, reprinted April 1972.
The Sea Fishes of Southern Africa, JLB Smith, 1949.
Smiths' Sea Fishes, MM Smith and PC Heemstra, 1986.
Two Oceans, A guide to the marine life of Southern Africa, GM Branch, CL Griffiths, ML Branch and LE Beckley, 1994.