| Rabbitfishes | |
|---|---|
| A Foxface Rabbitfish (S. vulpinus) meeting a Longnose Butterflyfish (above) in their coral reef habitat | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Superclass: | Osteichthyes |
| Class: | Actinopterygii |
| Subclass: | Neopterygii |
| Infraclass: | Teleostei |
| Superorder: | Acanthopterygii |
| Order: | Perciformes |
| Family: | Siganidae |
| Genus: | Siganus Forsskål, 1775 |
| Species | |
|
About 28, see text |
|
| Synonyms | |
|
Lo |
|
Rabbitfishes or spinefoots are perciform fishes in the family Siganidae. The 28 species are in a single genus, Siganus.[1] In some now obsolete classifications, the species having prominent face stripes—colloquially called foxfaces–are in the genus Lo. Other species like the Masked Spinefoot (S. puellus) show a reduced form of the stripe pattern. Rabbitfishes are found in shallow lagoons in the Indo-Pacific and eastern Mediterranean.[1]
Contents |
Rabbitfishes grow to about 40 cm (16 in)[1] and have small, rabbit-like mouths, large dark eyes, and a shy temperament which gives them their name; the scientific name Siganus is simply the Latin term by which Mediterranean rabbitfishes were known in Ancient Rome.[1] Most species have either bright colors or a complex and interesting pattern.
Another unusual feature among rabbitfishes is their pelvic fins, which are formed from two spines, with 3 soft rays between them. The dorsal fin bears 13 spines with 10 rays behind, while the anal fin has 7 spines and 9 rays behind; the fin spines are equipped with well-developed venom glands.[2] All rabbitfish are diurnal, some live in school, while others live more solitary lives among the corals. They are herbivorous, feeding on benthic algae in the wild. They are pelagic spawners. Many are fished for food, and the more colorful species—especially the foxfish – are often kept in aquaria.[1]
In aquaria, they eat a variety of fresh vegetables and algae. Care must be taken during aquarium maintenance and cleaning, as rabbitfishes are often easily frightened and will use their venomous spines in defense. Their venom is not life-threatening to adult humans, but causes severe pain.
In 2007 Kurriwa et al., outlined a way to split the genus—if the scientific community desires so:[3]
But other lineages might exist and obsolete the somewhat weak distinction between the second and third groups. Also, it is not known where the type species S. rivulatus would fall, hence names for these three subgenera or genera are not established at present.
Hybridizaton has played a role in the evolution of Siganidae, as evidenced by comparison of mtDNA cytochrome b and nDNA Internal transcribed spacer 1 sequence data. There is evidence of interbreeding between the Orange-spotted (S. guttatus) and the Golden-lined Spinefoot (S. lineatus), as well as between the Barred (S. doliatus) and the Barhead Spinefoot (S. virgatus).[3]
Also, either females of the last common ancestor of the Masked (S. puellus) and the Gold-spotted Spinefoot (S. punctatus) interbred with females ancestral to the main non-foxface lineage, or males of the former hybridized with females of the last common ancestor of the Peppered Spinefoot (S. punctatissimus) and the foxfaces, while males of the latter mated with females of the original foxface species.[3]
An individual was found that looked like a slightly aberrant Blue-spotted Spinefoot (S. corallinus). On investigation, it turned out to be an offspring of a hybrid between a female of that species and a male Masked Spinefoot, which had successfully backcrossed with the Blue-spotted Spinefoot.[3]
As noted above, several presumed species are suspected to actively interbreed even today; these might warrant merging as a single species. This applies to the White-spotted (S. canaliculatus) and the Mottled Spinefoot (S. fuscescens), and to the Blotched Foxface (S. unimaculatus) and the Foxface Rabbitfish (S. vulpinus). Alternatively they might be very recently-evolved species that have not yet undergone complete lineage sorting, but their biogeography suggests that each group is just color morphs of a single species. On the other hand, the morphologyically diverse Blue-spotted Spinefoot (S. corallinus) might represent more than one species; orange individuals are found at the north of its range, while yellow ones occur to the south, and these two may be completely parapatric. Some species of spinefoot have a very painful sting on each of their barbs, but some are a good eating fish.[3]