Posts tagged marine fish.
Photograph by Tim Laman
It’s hard to decide which of the colorful parrot fish’s many unique characteristics is most remarkable.
There’s its diet, which consists primarily of algae extracted from chunks of coral ripped from a reef. The coral is pulverized with grinding teeth in the fishes’ throats in order to get to the algae-filled polyps inside. Much of the sand in the parrot fish’s range is actually the ground-up, undigested coral they excrete.
There’s its gender, which they can change repeatedly throughout their lives, and their coloration and patterns, which are a classification nightmare, varying greatly, even among the males, females, and juveniles of the same species.
Finally, there are the pajamas. Every night, certain species of parrot fish envelope themselves in a transparent cocoon made of mucous secreted from an organ on their head. Scientists think the cocoon masks their scent, making them harder for nocturnal predators, like moray eels, to find.
Close relatives of the wrasse, parrot fish are abundant in and around the tropical reefs of all the world’s oceans. There are about 80 identified species, ranging in size from less than 1 to 4 feet (30 to 120 centimeters) in length.
Their meat is rarely consumed in the United States, but is a delicacy in many other parts of the world. In Polynesia, it is served raw and was once considered “royal food,” only eaten by the king.
Twinspot Goby (Signigobius biocellatus)
The twinspot goby spends much of its time hovering over the sea floor. When it is agitated, it will swim forward and backward in an erratic manner. The fins are held erect, exposing the large eye-spots. The lateral view of this goby, with the large ocelli, apparently mimics the “face” of a piscivorous fish and may discourage a predator from attacking. Some have suggested that the movement and appearance of this fish may serve to mimic a crab (in fact, some choose to call it the crab-eyed goby). However, this makes little sense seeing that crabs are a preferred food of many carnivorous fishes. Why would you try to resemble something that is commonly preyed upon?
Courtship and Spawning in Anthiinae
I laboured hard to actually work out which species this is, eventually I settled on that it is in fact an intensified/nuptual colouration of the Squareblock Anthias, (Pseudanthias pleurotaenia) - quite a special one in the case of the male it would seem.
I did wonder if it was either the Aurora Anthias, (Pseudanthias calloura) or Shen’s Anthias, (Pseudanthias sheni), but in the case of the first the range is wrong as well as the female colouration being different (amongst other things), and the second having an incredibly small natural range. Morphologically, the second is closer - but it’s limited to a tiny region off of Western Australia, whereas this is listed as having been taken off of Japan.
Anyone got any insight into it? I’m pretty confident in the ID, but certainly not 100% by any means.
DIVERSITY OF FORM AND COLOURATION AMONGST MARINE ANGELFISHES (family Pomacanthidae) - PART I (cont. Part II)
- Juvenile Goldflake Angelfish, (Apolemichthys xanthopunctatus).
- Mature Goldflake Angelfish, (Apolemichthys xanthopunctatus).
- Juvenile Blue Mauritius Angelfish, (Centropyge debelius).
- Mature Blue Mauritius Angelfish, (Centropyge debelius).
- Juvenile Bluelined Angelfish, (Chaetodontoplus septentrionalis).
- Mature Bluelined Angelfish, (Chaetodontoplus septentrionalis).
- Juvenile Spotted Swallowtail Angelfish, (Genicanthus takeuchii).
- Female (mature) Spotted Swallowtail Angelfish, (Genicanthus takeuchii).
- Male (mature) Spotted Swallowtail Angelfish, (Genicanthus takeuchii).
- Juvenile Clarion Angelfish, (Holacanthus clarionensis).
Frogfish with sponge
Frogfish are masters of camouflage often mimicking their immediate surroundings perfectly.
Photo: Andrew Taylor
That awkward moment when you point a Frogfish out to a fellow diver and they can’t see it. Followed by that awesome moment of eyes-widening-bubble-blowing-vigorous-nodding realization. Oh, and the ‘OK’ sign.
DIVERSITY OF FORM AND COLOURATION AMONGST MARINE ANGELFISHES (family Pomacanthidae) - PART II (cont. Part I)
- Mature Clarion Angelfish, (Holacanthus clarionensis).
- Juvenile Emperor Angelfish, (Pomacanthus imperator).
- Mature Emperor Angelfish, (Pomacanthus imperator).
- Juvenile Majestic Angelfish, (Pomacanthus navarchus).
- Mature Majestic Angelfish, (Pomacanthus navarchus).
- Juvenile French Angelfish, (Pomacanthus paru).
- Mature French Angelfish, (Pomacanthus paru).
- Juvenile Regal Angelfish, (Pygoplites diacanthus).
- Mature Regal Angelfish, (Pygoplites diacanthus).
Broadly speaking, the examples posted are typical of their subfamily/complex. Pomacanthus is the most diverse in terms of juvenile colour forms - 3 base forms in total - compared to a single form or a pair of colour forms per genus for the rest of the family.
Some genera exhibit sexual dichromatism, the most profound of these being the Genicanthus species, all of whom exhibit distinctive male and female colourations. To a much lesser extent, some Centropyge species exhibit this trait, however a more profound difference between the genders tends to be morphological in most species of the genus (for example, anal fin shape is a determining factor in the genders for most).
Some complexes exhibit eyespotting in juvenile forms. Others exhibit striation (either straight, raked, or concentric). All means are designed specifically for the purpose of confusing or evading prey during the juvenile stages.
Amongst the species of the family, quite a significant number exhibit regional variation. An example of this is the regional variations of the Flame Angelfish, (Centropyge loriculus), as written about by Richard Pyle et al. Others occupy a quantifiably tiny natural range and have total homogeneity to their form (Apolemichthys guezei, Centropyge abei, Centropyge boylei, Centropyge debelius, Centropyge hotumatua, Centropyge joculator, Centropyge resplendens, Chaetodontoplus ballinae, Chaetodontoplus niger, Holacanthus limbaughi).
All in all, the family Pomacanthidae is one of the most diverse on a per-species basis. Amongst the 89 currently acknowledged species, there is many significant different forms to be observed.