Blenniidae

Diversity

The family Blenniidae is the largest family in its suborder, consisting of six tribes with 53 genera and 345 species. A slender, elongate body and cryptic coloring assist many blennies in their secretive lifestyle in crevices and holes on the bottom of inshore waters. Blennies are known for their distinctive teeth, which are close-set in a single row on each jaw, and some blennies have a huge canine on each lower jaw, hence the descriptors “comb-toothed” and “saber-toothed." Blennies possess interesting traits ranging from mimicry and hopping over terrestrial rocks to adopting separate colors for courtship. Most blennies feed on algae and small invertebrates, but some attack other fish to steal bites of fin, scales, or skin.

Geographic Range

Blennies can be found in the Pacific, Indian, and Atlantic oceans, in tropical, subtropical, and temperate waters throughout the world.

• Biogeographic Regions
• oriental oriental
  • native native
• ethiopian ethiopian
  • native native
• neotropical neotropical
  • native native
• australian australian
  • native native
• oceanic islands oceanic islands
  • native native
• arctic ocean arctic ocean
  • native native
• indian ocean
  • native native
• atlantic ocean atlantic ocean
  • native native
• pacific ocean pacific ocean
  • native native
• mediterranean sea
  • native native

Habitat

While blennies are primarily marine fishes, some members of the family occur in estuaries or in fresh water, for example, in lakes in Italy. They inhabit shallow, inshore, often intertidal, waters. Blennies are generally benthic, occupying grass beds, tide pools, or areas near rocks, shells, or corals. The saber-toothed blennies, Aspidontus and Meiacanthus , are free swimming.

• Habitat Regions
• saltwater or marine saltwater or marine
• freshwater freshwater

• Aquatic Biomes
• benthic benthic
• reef reef
• lakes and ponds
• coastal coastal
• brackish water brackish water

• Other Habitat Features
• estuarine estuarine
• intertidal or littoral intertidal or littoral

Systematic and Taxonomic History

The Blenniidae family consists of six tribes: Salariini with 26 genera, Parablenniini with about 12 genera, Blenniini with two genera, Omobranchini with seven genera, Phenablenniini with one species, and Neomophini (saber-toothed blennies) with five genera (Smith-Vaniz 1976).

Blennies are one of several recently derived families ( Acanthuridae , Monacanthidae , Pomacentridae , Scaridae , Siganidae ) capable of exploiting reef algae and small colonial invertebrates. Reef herbivory was primarily restricted to post-Cretaceous perciformes until these families underwent rapid evolution during the early Tertiary, 50 to 30 million years ago.

Physical Description

Blennies have scaleless, elongated bodies, and comb-like, slender, close-set teeth, which can be either fixed or movable. A pair of giant canines give the saber-toothed blennies their name, and in the poison-fanged blennies ( Meiacanthus ) these teeth are hollow and contain an injectable toxin. In blennies the palatines are toothless, and the mouth not protractile. The head is often blunt and typically adorned with tentacles or cirri. Blennies are usually small, but a few can reach 55 cm. The dorsal fin has more rays than spines, and the anal fin has two spines. Blennies exhibit a wide variety of uniform colors as well as spots, stripes, or bands, and some species exhibit two or three color patterns. Cryptic coloring is widespread. (Click here to see a fish diagram ).

Sexual dimorphism is common to many of the blennies. In general males are larger than females and in some species have a larger head. The cirri on the head can take distinct forms in males and females, as can the anal spines. Males of some species have fleshy swellings near the dorsal or anal fins that become larger during spawning season. Many blennies assume spawning colors, most frequently the male, but sometimes the female as well. Males tend to develop brighter coloration during spawning, especially under the jaw, and in one species males take on a third color pattern while egg-tending.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry
• poisonous poisonous
• venomous venomous

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful
• sexes shaped differently
• ornamentation ornamentation

Development

Blennies generally pass through a pelagic, postlarval stage after a short planktonic stage. The young pelagic fishes look different enough from their adult form that they were classified at one time as a separate subfamily. Transformation into the adult form occurs at some time after the postlarvae enter a littoral habitat.

Reproduction

Blennies attract mates near the holes or crevices in which spawning occurs. The females will often initiate courtship, some assuming new coloration for spawning. When the female enters the area the male engages in courtship behavior that can include changing into spawning colors, bobbing the head up and down at the mouth of the cave, and leading the female to the nest by swimming with an undulating motion. One the male may mate with several females. Males of some species apparently move toward an olfactory cue released by other males during spawning.

• Mating System
• polygynous polygynous

It is probable that blennies spawn throughout the year, probably during the day. Some groups only spawn during warmer times of the year, and one species spawns every three to four days. Spawning usually occurs in the male’s territory in a cave, crevice, or other shelter. The male entices the female into the cave with various courtship behaviors (see Reproduction: Mating Systems), at which point she begins to lay eggs on the surfaces of the shelter. Spawning may take only a few minutes, or may last more than a day; eggs may be deposited all at once, or on several trips into the nest. Depending on the size of the cave, the male may enter with the female, or may make intermittent trips into the hole to fertilize the eggs. The male is generally active during spawning, deterring predators, and afterwards guarding the eggs until hatching. Females may occasionally guard the nest as well. One male may mate with several females, brooding all the eggs in the same nest.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • external external
• oviparous oviparous

Blennies deposit their eggs in clumps on the hidden surfaces of crevices or holes. The male, and sometimes the female, guards the eggs until they hatch, at which point the larvae are left to fend for themselves. During hatching some males energetically fan the eggs.

• Parental Investment
• male parental care male parental care
• female parental care female parental care

Lifespan/Longevity

There was no information found regarding the lifespan of blenniids.

Behavior

Blennies tend to be secretive, remaining near the bottom and hiding their eggs in crevices. Some hide in holes and dart out at their prey. Blennies may eat invertebrates or algae, or survive by nipping the skin, scales, or fins of other fish. Some blennies, known as “rock-hoppers,” are able to leap out of the water to cross the rocks between pools. A number of blenniids engage in mimicry. One saber-toothed blenny, Aspidontus taeniatus , mimics the cleaner wrasse Labroides dimidiatus . The blenny is able to approach and take a nip out of large fish that are accustomed to being cleaned by the nearly identical-looking wrasse. Several genera of blennies ( Ecsenius and Plagiotremus — also known as Runula ) gain protection from their resemblance to poison fanged blennies ( Meiacanthus ), who use venom defensively (see Predation).

• Key Behaviors
• natatorial natatorial
• diurnal diurnal
• motile motile
• territorial territorial
• social social

Communication and Perception

Other than descriptions of visual and olfactory communication during mating (see Reproduction: Mating Systems), no specific information was found concerning communication methods used by this group.

• Communication Channels
• visual visual
• chemical chemical

• Other Communication Modes
• mimicry mimicry

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Primarily bottom-dwellers, blennies tend to feed on other benthic organisms, both algae and invertebrates. Some are planktivores, some carnivores; others scrape algae off coral and rocks and in the process may be feeding on small organisms that live in association with the algae. Some blennies nip pieces of skin, scales, or fins from larger fish.

• Primary Diet
• carnivore carnivore
  • eats non-insect arthropods
• herbivore herbivore
• omnivore omnivore
• planktivore planktivore

Predation

Most blennies depend on a secretive lifestyle to survive, having coloration that blends in with their surroundings and hiding on the bottom in shallow waters. Some can escape predators by hopping over rocks from pool to pool. Meiacanthus can inject venom from the base of a groove in its large canine teeth. Any predator that gulps Meiacanthus apparently receives a toxic bite on the inside of its mouth and Meiacanthus is able to swim away freely. Several genera of blennies ( Ecsenius , Plagiotremus — also known as Runula ) gain protection from mimicking the coloration of Meiacanthus . Other blenniids engage in mimicry as well; one saber-toothed blenny, Aspidontus taeniatus , mimics the cleaner wrasse Labroides dimidiatus in color and behavior. The blenny is able to approach and take a nip out of large fish that are accustomed to being cleaned by the nearly identical-looking wrasse.

• Anti-predator Adaptations
• mimic
• cryptic cryptic

Ecosystem Roles

Blennies are largely herbivorous and as such play an important role in grazing reef algae, keeping it from smothering corals. Blennies are a predominant group in intertidal and inshore zones and are specialized to occupy holes and crevices.

• Ecosystem Impact
• parasite parasite

Economic Importance for Humans: Positive

Blenniids are not food fishes, but the genera Ecsenius , Salarias , and Meiacanthus are gathered for aquarium use.

• Positive Impacts
• pet trade pet trade

Economic Importance for Humans: Negative

No specific information was found concerning any negative impacts to humans.

Conservation Status

Currently, there is no known conservation threat to any member of this family.

Other Comments

The first fossil records of blenniids date from the upper Tertiary and upper Miocene periods.

Additional Links

Encyclopedia of Life

Contributors

Monica Weinheimer (author), Animal Diversity Web.

R. Jamil Jonna (author), Animal Diversity Web.

References

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