Blennies (from the Greek language ἡ βλέννα and τό βλέννος, mucus, slime) are a diverse clade of Actinopterygii in the suborder Blennioidei of the Percomorpha order Blenniiformes. They inhabit marine, brackish, and occasionally freshwater habitats, and generally share similar morphology and behaviour. About 151 Genus and nearly 900 species have been described within the order.
Taxonomy
The order was formerly classified as a suborder of the
Perciformes. However, the 5th Edition of
Fishes of the World divided the Perciformes into a number of new orders and the Blenniiformes were placed in the percomorph
clade Ovalentaria alongside the such taxa as
Cichliformes,
Mugiliformes and
Gobiesociformes.
added many more taxa, including the
and
Gobiesocidae, into the Blenniiformes, so the "true blennies" were redefined as the suborder Blennioidei.
The six "true blenny" families are:
The earliest known blennoid fossil is the
otolith-based species
Exallias vectensis from the
Early Eocene of France. However, skeletal remains of blennies only appear in the fossil record during the
Miocene.
Similarities with other families
The blennioids are superficially quite similar to members of the
goby and
dragonet families, as well as several other unrelated families whose members have occasionally been given the name "blenny". Many blennies demonstrate
mimicry of other species, such as
Aspidontus taeniatus. This mimicry allows the blenny to get up close to fish that would normally let
Labroides dimidiatus (the bluestreak cleaner wrasse), clean them. The blenny then takes nips or larger bites out of the unsuspecting fish. There are two genera of blennies that demonstrate
Batesian mimicry -
Ecsenius and
Plagiotremus.
Morphology
Blennioids are generally small fish, only occasionally reaching lengths up to 55 cm, with elongated bodies (some almost
eel-like), and relatively large eyes and mouths. Their dorsal fins are often continuous and long; the pelvic fins typically have a single embedded spine and are short and slender, situated before the pectoral fins. The tail fin is rounded. The blunt heads of blennioids often possess elaborate whisker-like structures called cirri.
Behavior and feeding
As generally
benthic fish, blennioids spend much of their time on or near the sea floor; many are reclusive and may burrow in sandy substrates or inhabit crevices in
, the lower stretches of rivers, or even empty
mollusc shells. Some blennies, otherwise known as "rock-hoppers", leap from the water onto rocks in order to reach other pools.
[Böhlke, J., C. Chaplin. 1994. Fishes of the Bahamas and Adjacent Tropical Waters. Wynnewood, Pa: Published for the Academy of Natural Sciences of Philadelphia by Livingston.][Helfman, G., B. Collete, D. Facey. 1997. The Diversity of Fishes. Malden, MA: Blackwell.][Moyle, P., J. Cech. 2000. Fishes: An Introduction to Ichthyology – fourth edition. Upper Saddle River, NJ: Prentice-Hall.][Springer, V. 1994. Blennies. Pp. 214–217 in W Eschmeyer, J Paxton, eds. Encyclopedia of Fishes – second edition. San Diego, CA: Academic Press.]
As far as predation, blennies depend on a secretive lifestyle, hiding on the sea floors in shallow water, with cryptic coloration.
Venom
For protection, there is only one genus that is truly venomous, namely
Meiacanthus. These fish can inject venom from their mandibular, hollow fangs.
[Wheeler, A. 1985. The World Encyclopedia of Fishes. London: Macdonald.] They have venom that contains the opioid-like
enkephalin,
phospholipase, and
neuropeptide Y.
[Losey GS. 1972. Predation protection in the poison-fang blenny, Meiacanthus atrodorsalis, and its mimics, Ecsenius bicolor and Runula laudandus (Blenniidae). Pac Sci 26(2): 129–139.]
Distribution
True blennies are widely distributed in coastal waters, often abundant and easily observed which has made them the subject for many studies of
ecology and behaviour. Two of the families, the Blennidae and the Tripterygiidae have global distributions, the Clinidae have a mainly
Temperate zone distribution and the remaining three families are largely
Neotropical. This distribution makes these fish ideal subjects for studies of
biogeography. It is thought that the splitting of the
Tethys Sea by the formation of the Isthmus of Panama combined with
Pliocene warming of the climate may have been important factors influencing the evolution and biogeography of the Blenniiformes.
==Gallery==
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in Port Noarlunga, South Australia]]
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, Entomacrodus marmoratus in Kona]]
