Facts: The Blenny

Blennies of the family Blenniidae are small, scaleless, mostly bottom-dwelling marine fish. There are over 300 species, all in various colors that can differ between males and females of the same species. They are distributed worldwide in tropical and warm temperate waters. They are occasionally found in brackish and freshwater. Blennies are typically seen in tide pools or peering from crevices and holes in coral reefs. Many species are highly territorial. Some species can jump between rock pools. Blennies are often confused with gobies, that also dwell on the bottom. However, blennies have one long dorsal fin while gobies have two. Blennies also tend to back into their hole's tail first, whereas gobies like to enter headfirst. Blennies can be divided into two groups, the bottom dwellers and the free swimmers. Bottom dwellers typically have blunt heads and they feed primarily on algae and detritus that they scrape from rocks with their wide mouths and comb-like teeth. They may also feed on small invertebrates. Bottom dwellers are poor swimmers. They lack swim bladders, hence they sink as soon as they stop moving. Outside of their hidey holes, they usually rest on rocks or coral. Free swimming saber-tooth blennies, also known as fang blennies, have narrow heads. They are carnivores. They possess swim bladders so that they swim freely and only retreat to their holes at night or when threatened. They have a set of curved fangs on their lower jaws that they can use in defense. If engulfed by a large fish, a fang blenny will bite the inside of its captor's mouth, enticing the predator to spit out its prey. Sometimes a blenny's fangs are venomous, allowing them to produce a stinging bite. Some species that are not venomous have been observed to mimic the coloration and behavior of venomous species, gaining protection from mistaken identity. Fang blennies may feed on mucus or bits of scale scraped or nipped from the sides of larger fish by making careful sneak attacks. One species copies the coloration and swimming pattern of the blue streak cleaner wrasse. When a fish approaches the imposter to have parasites removed, it loses a bit of skin or scale instead. Most blennies lay eggs in nests on the seafloor. Most species grow to less than 8 inches, except for the outliers like the hairtail blenny that grows to 22 inches long. For more marine facts, click the SUBSCRIBE button!!